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I'll also be hosting Rural Electric right after the Island Messenger at 7 pm until 9 pm
Art of Sacrifice is the debut album by dbkaos. Based in the South-West of
England, Dave Hickman, the man behind dbkaos, has had several years
experience programming synths and effects for the thirteen sample CD's
he's had released by Zero-G (the UK's leading sample CD producer).
This pedigree has enabled him to compose Art of Sacrifice, a well crafted vision into the future of synthesis. Using a computer as the main sound source with external audio contributions from a VCS3, Supernova II and of course access to his vast library of samples, the six tracks display a real sonic depth.
Whilst it might be assumed that such music would be routed firmly in the studio environment Hickman has in fact been actively pursuing a live performance path . Indeed dbkaos has started to build an excellent live reputation having performed several gigs in the burgeoning concert scene in the South-West of England. These include a support slot for System 7 promoted by The Future Sound of Exeter at the Phoenix Theatre in Exeter. Future events include a live set at the chillout zone at this years Midsummernight's Festival in Exeter where Art of Sacrifice will be officially launched followed by a support slot for a Hawkwind / Arthur Brown gig on the main stage at the Phoenix Center in Exeter on 25th October.
Musically Art of Sacrifice slots nicely into the DiN pantheon whilst retaining it's own individual character. Lush, ambient textures are overtaken by frenetic, complex sequencers. Trance like percussive sections give way to surrealistic, dream-like passages. The overall album has a real feeling of a journey although it's source and destination are ambivalent enough to allow the listener to formulate their own path. As such Art of Sacrifice perfectly crystallises one of the main aims of DiN to bridge the gap between electronic musics analogue ancestry with cutting edge digital soundscapes.
This pedigree has enabled him to compose Art of Sacrifice, a well crafted vision into the future of synthesis. Using a computer as the main sound source with external audio contributions from a VCS3, Supernova II and of course access to his vast library of samples, the six tracks display a real sonic depth.
Whilst it might be assumed that such music would be routed firmly in the studio environment Hickman has in fact been actively pursuing a live performance path . Indeed dbkaos has started to build an excellent live reputation having performed several gigs in the burgeoning concert scene in the South-West of England. These include a support slot for System 7 promoted by The Future Sound of Exeter at the Phoenix Theatre in Exeter. Future events include a live set at the chillout zone at this years Midsummernight's Festival in Exeter where Art of Sacrifice will be officially launched followed by a support slot for a Hawkwind / Arthur Brown gig on the main stage at the Phoenix Center in Exeter on 25th October.
Musically Art of Sacrifice slots nicely into the DiN pantheon whilst retaining it's own individual character. Lush, ambient textures are overtaken by frenetic, complex sequencers. Trance like percussive sections give way to surrealistic, dream-like passages. The overall album has a real feeling of a journey although it's source and destination are ambivalent enough to allow the listener to formulate their own path. As such Art of Sacrifice perfectly crystallises one of the main aims of DiN to bridge the gap between electronic musics analogue ancestry with cutting edge digital soundscapes.
credits
released July 1, 2003
ambient
david hickman
em
electronic
electronic music
electronica
idm
techno
modular synth
Sunderland
https://defensetechnologies.bandcamp.com/
More information to follow once it is declassified.
THE PSYCHOACOUSTIC RESPONSE TO SUSTAINED TONES AND REPETITIVE
MUSICAL STRUCTURES: APPLICATION
AS TACTICAL ASSETS AND PROTECTIVE COUNTERMEASURES
Field Applications Development Group
Technical Report
(Declassified – 2025 Release)
FORWARD: Defense Technologies is a private research organization that
develops, commercializes and brings to market key assets for defensive
and tactical use in today's modern world wars fought on battlefields of
today’s hearts and minds. Defense Technologies develops reliable
effective products that are proven to support the efforts and goals of your
organization.
This report has been developed to inform our market customerbase of the
extensive scientific principles and demonstrable phenomena that are the
theoretical bases that drives the success of our products.
1. INTRODUCTION TO
PSYCHOACOUSTICS IN
PSYCHOLOGICAL WARFARE
1.1 Psychoacoustics
Psychoacoustics is the branch of science concerned with how humans perceive and
interpret sound. Whereas acoustics deals with the measurable physical properties of
sound waves—frequency (Hz), amplitude (dB SPL), waveform shape—psychoacoustics
addresses the transduction of these waves into neural signals by the ear, and the
processing of those signals by the brain.
When the sound source is sustained (as in a drone) or repetitive (as in a looped
phrase), certain perceptual mechanisms begin to dominate over others. These
mechanisms include auditory adaptation, spectral integration, and temporal pattern
recognition, which together produce effects that can be calming, disorienting, or
entraining depending on the precise signal characteristics.
Key psychoacoustic principles in this context:
(a) Overtone Series and Harmonic Saturation
● A vibrating object produces a fundamental frequency and a series of
higher-frequency harmonics (integer multiples of the fundamental).
● The cochlea performs a frequency-to-place transformation, mapping these
components to specific hair cells along the basilar membrane.
● Sustained tones with rich overtone content lead to critical band overlap—where
multiple harmonics stimulate overlapping regions of the cochlea. This can result
in “beating” between partials close in frequency, perceived as a slow amplitude
modulation or “shimmer” [Helmholtz, 1877; Zwicker & Fastl, 1990].
● In a controlled environment, this shimmer can be tuned to produce either tension
(unstable beating) or relaxation (harmonically consonant beating).
(b) Induction of Aural Hallucinations
● When the auditory system receives highly repetitive, low-information input, the
predictive coding mechanisms of the brain attempt to fill in missing or anticipated
patterns.
● This can lead to the perception of phantom melodies, shifting timbres, or
whispered voices—well-documented in experiments with constant-tone or
constant-noise exposure (Kunchur, 2007).
● Such hallucinations occur because auditory cortex neurons show adaptation to
static input, reducing response to actual stimuli and increasing sensitivity to
internally generated neural noise.
(c) Rhythmic Induction of Trance States
● Repetition at rates matching neural oscillations (particularly in the alpha [8–12
Hz] and theta [4–8 Hz] ranges) can lead to entrainment—synchronization of brain
rhythms to the external auditory pulse.
● Entrainment modulates thalamocortical circuits, often producing states of focused
attention, mild dissociation, or heightened suggestibility (Nozaradan et al., 2011).
● These trance states are akin to those induced by traditional drumming in ritual
contexts, but can be reproduced with modern electronic loops of controlled
frequency and spectral content.
(d) Phase Interference Patterns
● When two sustained tones of nearly identical frequency are presented, their
waveforms alternately reinforce and cancel each other—producing beats at the
difference frequency.
● If these tones are spatially separated (e.g., from two speakers), spatial comb
filtering occurs, creating zones of high and low intensity in the environment.
● These moving interference patterns can cause shifting perceptions of pitch,
apparent location, and loudness—disrupting auditory spatial mapping in the
superior colliculus and vestibular stability in the inner ear.
In operational use, these mechanisms can be combined to:
● Maintain troop calmness during prolonged operations (alpha entrainment via
coherent harmonic drones).
● Disrupt enemy coordination (unstable beating fields causing disorientation).
● Mask communications (broad overtone saturation obscuring speech
frequencies).
1.2 Psychological Warfare
Psychological warfare (PSYWAR) refers to the deliberate use of information, imagery,
and sensory manipulation to influence the thoughts, emotions, and behaviors of target
populations or personnel. While historically associated with propaganda, leaflet drops,
and radio broadcasts, its acoustic dimension has long been recognized as both a subtle
and potent vector for influence with unique advantages.
● Pre-linguistic Impact – Non-semantic sound affects the limbic system directly,
bypassing language processing centers. This allows influence across cultural
and linguistic divides.
● Somatic Coupling – Low frequencies (< 100 Hz) can produce mechanical
coupling with body tissues, including the thorax and viscera, which can elicit
anxiety or excitement without conscious mediation.
● Persistence in Memory – Repetitive auditory sequences can create involuntary
memory traces (“earworms”), influencing mood and thought patterns for hours or
days after exposure.
Sound bypasses certain cognitive defenses because it is processed pre-attentively in
the auditory brainstem before higher-order meaning extraction in the cortex. This makes
acoustic content capable of influencing emotional state without explicit semantic content
— a quality leveraged in military morale operations, as well as in coercive interrogation
contexts.
Documented PSYWAR sound strategies have included:
● High-intensity noise exposure (for fatigue and disorientation)
● Targeted voice playback (leveraging language familiarity and prosody)
● Sustained-tone and drone application (for inducing trance states or perceptual
distortion)
● Repetitive musical structures (for conditioning and emotional anchoring)
The strategic application of psychoacoustic techniques in PSYWAR contexts seeks to
exploit limbic system vulnerabilities and neurocognitive biases in the human auditory
pathway.
During the Korean War and later Cold War, both East and West experimented with sonic
intimidation broadcasts—ranging from distorted music to pure tones—designed to
reduce morale. In many cases, the semantic content of the material was irrelevant; the
effect relied on perceptual fatigue, disorientation, and disruption of circadian rhythms
through prolonged exposure.
Acoustic methods form a subset of this toolkit, leveraging the non-optional nature of
auditory perception—ears cannot be “closed” as eyes can. Sustained tones and
repetitive patterns have unique potential in PSYWAR because:
● They can bypass conscious filtering, operating directly on subcortical auditory
pathways.
● They can alter emotional states without overt semantic content, allowing deniable
influence.
● They can function in both offensive (degrading enemy morale, sowing confusion)
and defensive (maintaining troop cohesion, masking hostile sonic intrusions)
capacities.
1.3 History of Psychoacoustics in Psychological Warfare
The intersection of psychoacoustics and psychological warfare began receiving formal
attention during the Second World War, when both Allied and Axis forces investigated
the morale effects of sound. While most operations focused on broadcast propaganda,
some units experimented with tonal drones and looped soundscapes transmitted via
loudspeaker arrays to induce unease or disrupt sleep cycles.
The U.S. Office of Strategic Services (OSS) documented early tests in which looped
mechanical noises were used to mask troop movements while simultaneously
producing low-grade cognitive disorientation. Similarly, Japanese forces reportedly
employed continuous percussion rhythms to unsettle prisoners, a tactic later studied in
postwar military psychology programs.
By the 1950s–1960s, Cold War research expanded into subsonic and ultrasonic
domains. Soviet infrasonic programs under Gavreau’s influence investigated the
destabilizing effects of low-frequency drones on cardiovascular and vestibular systems.
U.S. Naval and Air Force labs explored binaural beat entrainment as both an alertness
enhancement tool for pilots and a potential disorientation mechanism against
adversaries.
The psychoacoustic properties of phase interference became a subject of intense
classified interest when it was observed that layered repetitive patterns could produce
unpredictable perceptual “ghost rhythms,” sometimes causing involuntary motor
synchronization in test subjects — a potential vulnerability in battlefield coordination.
Scientific milestones relevant to military application:
● 1930s–40s: Research into the threshold of discomfort and loudness perception
by Fletcher and Munson established baseline curves still used in tactical acoustic
planning.
● WWII: British “Black Propaganda” units broadcast distorted music and artificial
battlefield sounds to enemy lines; the U.S. Army explored “sound camouflage” to
mask troop movement.
● 1950s: Soviet and U.S. laboratories investigated infrasonic (< 20 Hz) exposure,
finding associations with unease, nausea, and reduced concentration—later
confirmed in controlled psychoacoustic trials.
● 1960s–70s: Cognitive psychology began to model auditory pattern recognition,
phase perception, and adaptation effects—laying the groundwork for modern
loop/dronal warfare concepts.
1.4 History of Modern Development — Composers, Artists, and Scientific Context
The modern era of psychoacoustic exploration in a musical context can be traced
through a series of pivotal figures, each working in different cultural and technological
settings. Below is the chronological sequence, along with the scientific background that
illuminates their contributions to the field.
Igor Stravinsky (1913–1920s)
Stravinsky’s early 20th-century work, particularly The Rite of Spring (1913), introduced
repetitive rhythmic stratification and irregular metric cycles into Western concert music.
While not drone-based, the motoric persistence and predictive dissonance of these
rhythmic blocks engage auditory cortex pattern-recognition loops in ways later
confirmed to alter temporal perception. Contemporary research by Henning (1904) on
rhythm perception provided early evidence of physiological synchronization to external
pulse. In the 1910s and 1920s, experimental psychologists such as Carl Seashore
were developing early models of rhythmic perception, noting that high-intensity,
irregular-but-repetitive rhythms could shift attention and alter perceived time duration.
Research on auditory chunking (Miller, 1956) and expectancy violation (Huron, 2006)
provides a post-hoc framework for understanding the heightened tension in Stravinsky’s
ostinati.
Edgard Varèse (1920s–1950s)
Varèse’s fascination with pure tone blocks and siren glissandi (Ionisation, 1931) aligns
with early studies on continuous pitch motion and its ability to disrupt tonal anchoring
(Deutsch, 1980). His work parallels the 1930s–40s Bell Labs studies on critical band
masking and the psychological fatigue induced by broadband noise exposure. His later
embrace of electronic instruments anticipated laboratory research into auditory scene
analysis and the effects of frequency sweeps on attention redirection. Varèse’s
exploration of sirens and sustained electronic tones in works like Ionisation paralleled
emerging research on auditory fatigue and the destabilizing effects of pure tones on
spatial orientation (Stevens & Davis, 1938). Sustained high-density spectra are known
to accelerate auditory adaptation, reducing situational awareness—a fact later
weaponized in high-noise battlefield conditions.
Anton Webern (1930s–1940s)
Webern’s extreme use of silence and pointillistic tone events (Symphony Op. 21, 1928)
parallels psychoacoustic research on temporal masking and auditory gap detection
thresholds. Webern’s highly concentrated miniatures, though brief, utilized tone color
melodies (Klangfarbenmelodie) and carefully spaced intervals to maximize the
perceptual weight of each sound. Research in this era (Békésy, 1928) on auditory
masking and temporal resolution revealed mechanisms by which sparse, isolated tones
could heighten the perceptual salience of sustained sounds in other registers. Research
in the 1930s by Harvey Fletcher and E.C. Wente showed that the brain can “fill in”
missing sound elements if spectral cues are maintained. The sparseness in Webern’s
music exploits the brain’s tendency to “fill in” missing sound events — a phenomenon
that can induce illusory continuity effects (Miller & Licklider, 1950). The psychoacoustic
relevance lies in his manipulation of temporal sparsity—forcing the listener’s predictive
mechanisms to work harder, a condition known to enhance illusory continuity perception
(Warren et al., 1972).
Giacinto Scelsi (1950s–1980s)
Scelsi’s sustained-tone works (Quattro Pezzi su una nota sola, 1959) explore the
microstructure of a single pitch. Scelsi’s focus on single notes and microtonal inflections
directly engaged overtone perception and beating phenomena. These pieces align with
research on cochlear microphonic adaptation and overtone fusion, wherein slowly
shifting spectra within a fixed fundamental produce perceptual richness without
harmonic movement. In the 1950s and 1960s, psychoacoustic research (Plomp &
Levelt, 1965) clarified how roughness and beating between close partials create
emotional valence shifts—ranging from tension to serenity. Scelsi’s control of
slow-beating partials mirrors methods used to either calm or destabilize listeners in
controlled acoustic environments. Military interest in Scelsi’s approach centered on the
psychological persistence of single-tone exposure and its trance-inducing potential.
This period saw advancements in understanding cochlear microphonics and the
brainstem’s role in pitch discrimination (Rose et al., 1962).
Krzysztof Penderecki (1960s)
Penderecki’s tone clusters (Threnody for the Victims of Hiroshima, 1960) produce
critical-band roughness, a psychoacoustic condition wherein multiple close frequencies
excite overlapping cochlear regions, creating tension and sensory overload. Studies in
the early 1960s (Zwicker, Fastl) quantified the spectral masking and temporal
dissonance such textures produce. Studies on roughness perception (Plomp & Levelt,
1965) clarify why Penderecki’s dense textures elicit visceral unease. Similarly, research
into sensory overload, autonomic arousal, and the startle reflex in relation to dissonant
spectra (Gatchel & Prokasy, 1968) informs this interpretation.Prolonged exposure has
been shown to induce heightened anxiety and confusion, particularly when the
spectrum contains inharmonic partials that resist tonal anchoring.
Steve Reich (1960s–1970s)
Reich’s phase music (Piano Phase, 1967) directly embodies phase interference
principles. His work anticipated laboratory findings that slowly shifting phase
relationships between identical patterns can produce emergent “ghost rhythms” and
induce temporal hallucinations (Bregman, 1978) and hemispheric synchronization
(Oster, 1973).
Robert Fripp (1970s–1990s)
Fripp’s “Frippertronics” — dual-reel tape delay looping — created continuously evolving
drones with overlapping phrase cycles. Research in the late 1960s–70s into echoic
memory (Darwin, Turvey, & Crowder, 1972) found that short-term auditory storage
interacts with ongoing sound in ways that can enhance immersion and reduce the
listener’s perception of discrete time intervals. Fripp’s loops effectively extend the
auditory present, a principle also useful in distraction or orientation-disruption
applications. These textures generate perceptual blending effects similar to those
observed in studies of auditory stream fusion and entrainment decay (Zatorre & Belin,
2001) and temporal integration windows in auditory cortex (Cowan, 1984).Layered
delays created temporal smearing—blurring the onset of new events into the decay of
old ones.
Manuel Göttsching /Ash Ra (1970s - 1980s)
Göttsching’s E2–E4 (1984) is a long-form minimalist piece sustained almost entirely on
looping motifs and subtle harmonic color shifts. This has been shown to induce trances
via minimal harmonic movement and stable rhythmic frameworks, correlating with EEG
studies of repetitive-music-induced alpha coherence (Flohr, 1989). From a
psychoacoustic standpoint, it exploits low attentional load repetition to induce a relaxed
vigilance state — a condition quantified in vigilance decrement studies (Parasuraman,
1979). Studies of flow states and alpha–theta entrainment (Gruzelier, 2009) show that
moderately complex, repetitive stimuli can shift brain activity toward patterns associated
with meditative absorption. Göttsching’s balance of constancy and evolution is a
textbook case for sustaining these states over operationally useful time spans.
Boards of Canada (1990s–2000s)
This duo employs detuned loops, tape warble, low-fidelity drones and looping motifs to
create spectral instability and temporal smearing that evoke nostalgia and subtle
unease. The detuning produces slow beat frequencies, while the degraded
high-frequency content simulates aged media—engaging memory systems differently
than “clean” audio. Such qualities mirror research on degraded auditory cues and
memory recall distortion (Lehmann & Seufert, 1999), relevant in psychological
disorientation contexts. Research on context-dependent memory (Godden & Baddeley,
1975) and affective conditioning indicates that such spectral cues can trigger
autobiographical recall or a sense of temporal dislocation. The effects of degraded
timbres, and cyclic motifs aligns with research into memory-triggered emotional
response via timbral nostalgia cues (Janata et al., 2002). In tactical applications, this
can be used to bias mood states, evoke familiarity, or induce low-level cognitive
dissonance.
Sunn O))) (2000s–present)
Sunn O)))’s ultra-low-frequency drones directly engage vestibular as well as auditory
systems, activating subcortical vibrotactile and vestibular arousal pathways, shown in
research on infrasonic effects on mood and physiological stress markers (Tandy &
Lawrence, 1998). Studies in infrasonic perception (Leventhall, 2007) confirm that
sustained sub-20 Hz components can induce anxiety, altered breathing, and even mild
vertigo — effects with obvious tactical implications. Sustained low-frequency pressure
waves engage the autonomic nervous system, increasing heart rate variability and
galvanic skin response—effects potentially deployable in crowd control or deterrence.
2. Theory of Sustained Tones and
Repetitive Musical Structures
2.1 Acoustic and Neurophysiological Foundations
Sustained tones and repetitive musical structures derive their psychoacoustic potency
from fundamental properties of the human auditory system, many of which evolved for
survival rather than artistic appreciation. The cochlea, a spiral-shaped organ in the inner
ear, functions as a frequency analyzer — decomposing incoming sound into its
component frequencies via the basilar membrane’s tonotopic organization.
A single sustained tone excites a narrow region of the basilar membrane. Over time,
neural adaptation reduces firing rates of auditory nerve fibers tuned to that frequency,
altering the subjective timbre and making overtones or environmental sounds more
perceptible. This spectral shift in awareness is central to trance induction: as the
primary stimulus “fades” perceptually, the brain’s attention is freed to wander while still
being anchored to a constant sonic reference.
In repetitive structures, temporal regularity entrains neural oscillators in the auditory
cortex and motor planning areas. This entrainment is mediated by
cortico-striatal-thalamo-cortical loops, and it can operate at multiple metrical levels
simultaneously. The listener’s internal model of timing adjusts to match the external
periodicity, reducing prediction error — a phenomenon quantified in predictive coding
models of auditory processing (Friston, 2005).
2.2 Overtones and Harmonic Spectrum Effects
Overtones, whether harmonic (integer multiples of the fundamental) or inharmonic,
contribute significantly to the perceived character of sustained sounds. Psychoacoustic
studies have demonstrated that spectral centroid (a measure of brightness) directly
influences emotional valence judgments: higher centroid tones are more likely to be
perceived as tense or alerting, while lower centroid tones evoke calm or ominous
impressions (Sethares, 2005).
The missing fundamental effect — the perception of a pitch at the greatest common
divisor of a harmonic series even when the fundamental frequency is absent — is
relevant in both music and military applications. In noisy or degraded transmission
environments, the brain’s pitch extraction mechanisms can still lock onto an implied
tonal center, allowing a drone’s influence to persist even if its physical representation is
masked by environmental noise or countermeasures.
● Critical bands: Plomp & Levelt (1965) showed that when two partials fall within
the same critical band (~1⁄3 octave), beating and roughness occur, eliciting
tension and heightened alertness.
● Harmonicity vs. inharmonicity: Terhardt (1974) demonstrated that harmonic
spectra are perceived as stable and soothing, while inharmonic spectra resist
tonal anchoring, increasing perceptual uncertainty.
● Sustained tones with slight detuning can induce emotional instability or mild
anxiety.
● Pure harmonic stacks can promote calm and trust, useful in entrainment or
conditioning scenarios.
2.3 Phase Interference and Temporal Perception
When two tones of similar but not identical frequency are presented simultaneously,
their interaction produces beats — amplitude fluctuations at the difference frequency. At
low difference frequencies (≤ 10 Hz), these beats can entrain brainwave patterns in the
alpha (8–12 Hz) or theta (4–8 Hz) ranges, states associated with relaxed alertness or
meditative trance.
At slightly larger frequency separations, the auditory system perceives a shimmering or
pulsing effect known as roughness, a sensation arising from the competition between
overlapping critical bands on the basilar membrane (Plomp & Levelt, 1965). This
roughness is inherently aversive for many listeners and can be exploited for
destabilization in psychological operations.
In complex repetitive structures, slow phase shifts between multiple patterns produce
temporal hallucinations — the perception of rhythms, melodies, or accents not
physically present in the stimulus. Such illusory patterns can distract attention, alter time
perception, and impair cognitive task performance, especially in sustained exposure
scenarios.
● Studies of binaural beats (Oster, 1973) show that when two slightly different
tones are presented separately to each ear, the brain perceives an illusory third
“beat” frequency corresponding to their difference. This can entrain neural
oscillations toward alpha (relaxation) or theta (hypnosis) bands.
● Amplitude modulation and phase cancellation can cause subtle rhythmic pulses
within sustained tones, altering attention and perceived motion in the sound field.
● Binaural and monaural beat induction can be used to modulate alertness,
suppress resistance, or induce trance states without overt rhythmic content.
● Moving interference fields can disorient targets in a space through shifting
loudness zones.
2.4 Neuro-Rhythmic Entrainment and Cognitive State Modulation
The phenomenon of neural entrainment describes the synchronization of endogenous
neural oscillations to external rhythmic stimuli. This is not limited to the auditory cortex
— subcortical structures such as the inferior colliculus and reticular formation are also
sensitive to periodicity, enabling rhythmic sound to influence arousal, vigilance, and
motor coordination.
● High-frequency rhythmic stimuli (> 12 Hz) can enhance cortical excitability and
alertness.
● Low-frequency stimuli (< 8 Hz) tend to induce relaxation, drowsiness, or
trance-like absorption.
From a tactical perspective, the capacity to manipulate opponent vigilance states
without overt semantic content makes sustained tones and repetitive structures
particularly valuable. The listener may remain unaware of the physiological entrainment,
interpreting the altered state as fatigue, boredom, or ambient influence rather than
deliberate conditioning.
● Large-scale research (Nozaradan et al., 2011) confirmed that the brain’s motor
system entrains to musical pulse even without overt movement.
● EEG phase-locking studies show increased alpha or theta power during
repetitive low-tempo rhythmic exposure.
● Steady rhythmic pulses at specific tempos can facilitate hypnotic induction or
group synchronization.
● Slight disruption of rhythmic regularity after entrainment can provoke heightened
suggestibility.
2.5 Emotional Valence and Conditioning
Psychoacoustic conditioning exploits the fact that repetition strengthens associative
learning between a stimulus and an emotional response. A sustained tone or repeating
pattern paired with a particular emotional or situational context can become a
conditioned auditory trigger.
For example:
● A specific drone frequency played during stressful events can later induce
anxiety even in neutral settings.
● Conversely, a repetitive ambient loop paired with positive reinforcement can
generate calming associations.
These mechanisms are well-documented in Pavlovian auditory conditioning research
(Bouton, 2007) and have direct relevance for both psychological operations and
protective countermeasures.
2.6 Psychoacoustic Vulnerabilities and Protective Factors
While the human auditory system is highly adaptive, it is not immune to long-term
modulation by repetitive or sustained sound exposure. Potential vulnerabilities include:
● Reduced vigilance due to habituation.
● Distorted time perception under entrainment.
● Emotional dysregulation through conditioned associations.
Protective countermeasures involve spectral diversity (frequent timbral changes),
temporal irregularity (syncopation, metric shifts), and masking noise to disrupt tonal
stability. In sensitive operations, dynamic spectral scrambling can prevent hostile tonal
conditioning without requiring high sound levels.
2.7 Auditory Scene Analysis and Perceptual Grouping
Proposed by Bregman (1990), this is the process by which the auditory system
organizes sound into perceptually distinct objects or “streams.”
● Listeners group sounds by similarity, continuity, and temporal proximity. Gradual
transformations—like Reich’s phase processes—force continual regrouping,
extending attentional engagement without abrupt change.
● Overlapping harmonic and noise elements can fuse into a perceptually single
“wall of sound,” obscuring source identification.
● Used in masking communications or embedding subliminal cues.
● Can prolong focus on a sonic environment while inhibiting conscious analysis of
its structure.
2.8 Temporal Smearing and Echoic Memory Manipulation
Temporal smearing occurs when sound reflections, delays, or loops blur the distinction
between successive events. Echoic memory stores these overlapping sounds for ~2–4
seconds, creating a fused auditory image.
● Darwin, Turvey, & Crowder (1972) demonstrated that delayed repetitions can
overwrite or blend with the original sound in memory.
● This effect is enhanced in reverberant spaces or with tape/digital loop systems
like Frippertronics.
● Reduces the ability to time events accurately, potentially impairing coordination or
perception of sequence.
● Can deepen immersion in continuous sonic environments, promoting passive
listening states.
2.9 Infrasound and Low-Frequency Resonance
Infrasound refers to frequencies below ~20 Hz, often perceived through tactile or
vestibular sensation rather than hearing.
● Tandy & Lawrence (1998) linked infrasound exposure (~17 Hz) to sensations of
dread, disorientation, and visual disturbances.
● Gavreau’s work in the 1960s on infrasound “cannons” showed that sustained
low-frequency pressure waves can induce nausea or panic.
● Effective in crowd dispersal, psychological intimidation, or inducing physiological
discomfort.
● May act synergistically with visual or narrative cues to amplify emotional impact.
2.10 Nostalgia and Memory Priming through Timbre Degradation
Spectral cues resembling older recording technologies (tape hiss, wow/flutter,
bandwidth limits) trigger associative memory systems differently than pristine
recordings.
● Godden & Baddeley (1975) demonstrated context-dependent recall: matching
environmental cues enhance memory retrieval.
● Zatorre & Halpern (1993) showed that imagined music recruits similar neural
pathways as heard music—suggesting degraded timbres can “activate” personal
past auditory imagery.
● Used for emotional priming before persuasive communication.
● Can evoke familiarity or vulnerability, lowering resistance to influence.
3. Applications in Psychological Warfare
3.1 Historical Precedents and Tactical Context
The use of sustained tones and repetitive musical figures in military and paramilitary
operations predates the formal science of psychoacoustics. From the horn blasts of
Bronze Age warfare to the drone-based shamanic ceremonies of nomadic tribes, sound
has been employed to shape mental states at both the individual and collective level.
During the 20th century, advances in recording, amplification, and transmission
technology enabled the deployment of complex psychoacoustic strategies over large
areas. Notable instances include:
● WWII-era propaganda broadcasts that embedded steady tonal beds under
speech to manipulate attention and induce passive listening.
● Vietnam-era sound warfare such as Operation Wandering Soul, where repetitive
motifs and drones mimicking funeral rites were broadcast at night to unnerve
opponents.
● Cold War research programs (both U.S. and Soviet) into low-frequency sound
exposure, rhythmic induction, and “infrasound fields” designed for crowd control
or troop disorientation.
The underlying concept remained consistent: repeated or sustained auditory stimuli
could alter arousal, cognition, and emotional regulation without overtly revealing their
influence.
3.2 As Protective Defense
3.2.1 Mechanisms of Efficacy
Defensive deployment of sustained tones and loops aims to stabilize the listener’s
cognitive state, creating resilience against adversarial attempts at auditory conditioning
or psychological manipulation.
Key mechanisms include:
● Auditory Anchoring: A familiar drone or loop can act as a perceptual reference
point, reducing the effectiveness of foreign or disruptive sound stimuli.
● Cognitive Load Saturation: By occupying the auditory processing system with a
controlled, predictable signal, hostile sonic content is partially masked or
cognitively deprioritized.
● Physiological Entrainment to Desired States: Defensive tones can be tuned to
frequencies that promote alertness during potential disorientation attempts, or
calm during anticipated panic induction.
3.2.2 Operational Techniques
● Use of broadband harmonic drones incorporating beneficial overtone structures
to counteract tonal masking attacks.
● Strategic deployment of phase-shifted loops to nullify opponent beat induction or
illusory rhythm creation.
● Spectral camouflage — embedding defensive tones in environmental noise
(machinery hum, HVAC resonance) to maintain continuous influence without
overt presence.
3.2.3 Limitations and Risks
● Prolonged exposure to any fixed tonal environment can produce habituation,
reducing protective effects over time.
● If improperly tuned, defensive drones may inadvertently entrain the listener to a
state that is less operationally advantageous (e.g., mild drowsiness).
● In contested environments, defensive sound sources may be detected and
co-opted by adversarial forces.
3.3 As Tactical Offense
3.3.1 Mechanisms of Efficacy
Offensive use of psychoacoustic repetition exploits vulnerabilities in neural prediction
systems and limbic responses to create discomfort, impair task performance, or induce
disorientation.
Primary offensive strategies include:
● Temporal Disruption: Introducing slow phase drift between multiple loops to
generate perceptual uncertainty about tempo and time passage.
● Spectral Fatigue: Sustained tones within sensitive auditory bands (2–4 kHz) that
induce discomfort while avoiding immediate pain thresholds.
● Associative Conditioning: Pairing drones with negative events to create lasting
aversive triggers in the target population.
Scientific literature on auditory salience and vigilance decrements (Warm,
Parasuraman, Matthews, 2008) supports the idea that continuous low-level auditory
demand can degrade situational awareness, particularly in high-stakes environments.
3.3.2 Operational Techniques
● Multi-Layered Loops: Stacking repetitive elements of differing cycle lengths to
produce emergent complexity and cognitive overload.
● Psychoacoustic Camouflage: Embedding dissonant micro-intervals or detuned
layers to create unconscious tension.
● Dynamic Modulation: Gradual frequency or amplitude shifts below conscious
detection thresholds to destabilize the target’s perceptual adaptation.
3.3.3 Limitations and Risks
● Overuse can lead to target desensitization, requiring constant adaptation of
material.
● Effects may vary significantly across individuals depending on cultural and
personal musical exposure.
● In certain contexts, unintended resonance with environmental structures can
amplify or nullify intended effects.
3.4 Combined Defensive and Offensive Scenarios
In modern operations, it is increasingly common for both defensive and offensive sonic
strategies to operate simultaneously within the same acoustic space. In such cases,
phase-domain tactics become crucial — deliberately synchronizing or desynchronizing
sonic fields to either reinforce or cancel each other’s influence.
Examples include:
● Urban peacekeeping operations where protective ambient sound masking is
deployed in civilian areas while targeted psychoacoustic disruption is directed
toward hostile actors.
● Electronic counter-countermeasures in which protective drones are modulated to
disrupt opponent beat-induction loops.
4. Summary and Conclusions
4.1 Summary of Findings
This review describes the substantial corpus of evidence that demonstrates sustained
tones and repetitive musical structures exert measurable psychoacoustic effects with
both protective and offensive utility in the context of psychological warfare.
Key observations include:
1. Physiological Entrainment:
Sustained or repeating signals can synchronize neural oscillations to desired
tempos, modulating arousal and attention. This effect can be leveraged to
promote alertness, reduce anxiety, or induce confusion.
2. Overtone and Harmonic Influence:
Carefully selected harmonic structures — particularly those with prominent
low-order overtones — can create stabilizing or destabilizing sensations in
listeners, depending on deployment.
3. Phase Interference as a Tactical Tool:
Multiple looping phrases of differing lengths or slight detuning produce evolving
interference patterns. These patterns can evoke altered temporal perception,
disorientation, or trance-like focus.
4. Historical Precedent and Scientific Correlation:
The lineage from early 20th-century composers (Stravinsky, Webern, Varèse)
through modern practitioners (Reich, Fripp, Göttsching, Sunn O))) and others)
demonstrates a continuous refinement of these techniques, paralleled by
advancements in psychoacoustic science.
5. Dual-Use Potential:
The same tonal strategies capable of inducing disorientation in adversaries can
be reconfigured to provide mental anchoring and resilience against sonic
manipulation.
4.2 Tactical Implications
The findings strongly suggest that acoustic domain operations deserve parity with
visual, electromagnetic, and information-domain tactics in strategic planning. Given the
low logistical footprint of sustained-tone deployment (relative to visual or kinetic
systems), psychoacoustic measures offer a cost-effective and adaptable addition to field
operations.
Defensively, harmonic drones and controlled repetition can form a cognitive shield,
reducing susceptibility to auditory suggestion, propaganda, or rhythmic entrainment by
adversaries. Offensively, asynchronous loops, dissonant overtones, and phase-shift
patterns can disrupt group coordination, degrade morale, and impair fine motor
performance.
4.3 Recommendations for Further Research
1. Expanded Cross-Cultural Testing:
Psychoacoustic responses are influenced by cultural conditioning; trials across
varied musical traditions will improve reliability of tactical deployment.
2. Integration with Neurophysiological Monitoring:
Real-time EEG and heart-rate variability monitoring during loop/drone exposure
will enable closed-loop adjustment of sonic parameters for maximum effect.
3. Investigation of Sub-Audible and Supra-Audible Domains:
Further study into infrasonic and ultrasonic repetition patterns may yield
additional tactical channels that bypass conscious auditory filtering.
4. Long-Term Exposure Studies:
Understanding habituation thresholds and potential adverse effects is essential
for sustained defensive use in occupied or contested zones.
4.4 Final Conclusion
The convergence of musicology, acoustic engineering, and psychological operations
research now makes it possible to apply the subtle art of sustained tones and repetition
as a scientifically grounded tactical discipline.
Whether as a stabilizing field for friendly forces or a disorienting field for hostile actors,
the principles outlined herein provide the basis for immediate field trials and eventual
doctrinal integration.
Field Applications Development Group, Defense Technologies Division
Classified – For Authorized Distribution Only
MUSICAL STRUCTURES: APPLICATION
AS TACTICAL ASSETS AND PROTECTIVE COUNTERMEASURES
Field Applications Development Group
Technical Report
(Declassified – 2025 Release)
FORWARD: Defense Technologies is a private research organization that
develops, commercializes and brings to market key assets for defensive
and tactical use in today's modern world wars fought on battlefields of
today’s hearts and minds. Defense Technologies develops reliable
effective products that are proven to support the efforts and goals of your
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This report has been developed to inform our market customerbase of the
extensive scientific principles and demonstrable phenomena that are the
theoretical bases that drives the success of our products.
1. INTRODUCTION TO
PSYCHOACOUSTICS IN
PSYCHOLOGICAL WARFARE
1.1 Psychoacoustics
Psychoacoustics is the branch of science concerned with how humans perceive and
interpret sound. Whereas acoustics deals with the measurable physical properties of
sound waves—frequency (Hz), amplitude (dB SPL), waveform shape—psychoacoustics
addresses the transduction of these waves into neural signals by the ear, and the
processing of those signals by the brain.
When the sound source is sustained (as in a drone) or repetitive (as in a looped
phrase), certain perceptual mechanisms begin to dominate over others. These
mechanisms include auditory adaptation, spectral integration, and temporal pattern
recognition, which together produce effects that can be calming, disorienting, or
entraining depending on the precise signal characteristics.
Key psychoacoustic principles in this context:
(a) Overtone Series and Harmonic Saturation
● A vibrating object produces a fundamental frequency and a series of
higher-frequency harmonics (integer multiples of the fundamental).
● The cochlea performs a frequency-to-place transformation, mapping these
components to specific hair cells along the basilar membrane.
● Sustained tones with rich overtone content lead to critical band overlap—where
multiple harmonics stimulate overlapping regions of the cochlea. This can result
in “beating” between partials close in frequency, perceived as a slow amplitude
modulation or “shimmer” [Helmholtz, 1877; Zwicker & Fastl, 1990].
● In a controlled environment, this shimmer can be tuned to produce either tension
(unstable beating) or relaxation (harmonically consonant beating).
(b) Induction of Aural Hallucinations
● When the auditory system receives highly repetitive, low-information input, the
predictive coding mechanisms of the brain attempt to fill in missing or anticipated
patterns.
● This can lead to the perception of phantom melodies, shifting timbres, or
whispered voices—well-documented in experiments with constant-tone or
constant-noise exposure (Kunchur, 2007).
● Such hallucinations occur because auditory cortex neurons show adaptation to
static input, reducing response to actual stimuli and increasing sensitivity to
internally generated neural noise.
(c) Rhythmic Induction of Trance States
● Repetition at rates matching neural oscillations (particularly in the alpha [8–12
Hz] and theta [4–8 Hz] ranges) can lead to entrainment—synchronization of brain
rhythms to the external auditory pulse.
● Entrainment modulates thalamocortical circuits, often producing states of focused
attention, mild dissociation, or heightened suggestibility (Nozaradan et al., 2011).
● These trance states are akin to those induced by traditional drumming in ritual
contexts, but can be reproduced with modern electronic loops of controlled
frequency and spectral content.
(d) Phase Interference Patterns
● When two sustained tones of nearly identical frequency are presented, their
waveforms alternately reinforce and cancel each other—producing beats at the
difference frequency.
● If these tones are spatially separated (e.g., from two speakers), spatial comb
filtering occurs, creating zones of high and low intensity in the environment.
● These moving interference patterns can cause shifting perceptions of pitch,
apparent location, and loudness—disrupting auditory spatial mapping in the
superior colliculus and vestibular stability in the inner ear.
In operational use, these mechanisms can be combined to:
● Maintain troop calmness during prolonged operations (alpha entrainment via
coherent harmonic drones).
● Disrupt enemy coordination (unstable beating fields causing disorientation).
● Mask communications (broad overtone saturation obscuring speech
frequencies).
1.2 Psychological Warfare
Psychological warfare (PSYWAR) refers to the deliberate use of information, imagery,
and sensory manipulation to influence the thoughts, emotions, and behaviors of target
populations or personnel. While historically associated with propaganda, leaflet drops,
and radio broadcasts, its acoustic dimension has long been recognized as both a subtle
and potent vector for influence with unique advantages.
● Pre-linguistic Impact – Non-semantic sound affects the limbic system directly,
bypassing language processing centers. This allows influence across cultural
and linguistic divides.
● Somatic Coupling – Low frequencies (< 100 Hz) can produce mechanical
coupling with body tissues, including the thorax and viscera, which can elicit
anxiety or excitement without conscious mediation.
● Persistence in Memory – Repetitive auditory sequences can create involuntary
memory traces (“earworms”), influencing mood and thought patterns for hours or
days after exposure.
Sound bypasses certain cognitive defenses because it is processed pre-attentively in
the auditory brainstem before higher-order meaning extraction in the cortex. This makes
acoustic content capable of influencing emotional state without explicit semantic content
— a quality leveraged in military morale operations, as well as in coercive interrogation
contexts.
Documented PSYWAR sound strategies have included:
● High-intensity noise exposure (for fatigue and disorientation)
● Targeted voice playback (leveraging language familiarity and prosody)
● Sustained-tone and drone application (for inducing trance states or perceptual
distortion)
● Repetitive musical structures (for conditioning and emotional anchoring)
The strategic application of psychoacoustic techniques in PSYWAR contexts seeks to
exploit limbic system vulnerabilities and neurocognitive biases in the human auditory
pathway.
During the Korean War and later Cold War, both East and West experimented with sonic
intimidation broadcasts—ranging from distorted music to pure tones—designed to
reduce morale. In many cases, the semantic content of the material was irrelevant; the
effect relied on perceptual fatigue, disorientation, and disruption of circadian rhythms
through prolonged exposure.
Acoustic methods form a subset of this toolkit, leveraging the non-optional nature of
auditory perception—ears cannot be “closed” as eyes can. Sustained tones and
repetitive patterns have unique potential in PSYWAR because:
● They can bypass conscious filtering, operating directly on subcortical auditory
pathways.
● They can alter emotional states without overt semantic content, allowing deniable
influence.
● They can function in both offensive (degrading enemy morale, sowing confusion)
and defensive (maintaining troop cohesion, masking hostile sonic intrusions)
capacities.
1.3 History of Psychoacoustics in Psychological Warfare
The intersection of psychoacoustics and psychological warfare began receiving formal
attention during the Second World War, when both Allied and Axis forces investigated
the morale effects of sound. While most operations focused on broadcast propaganda,
some units experimented with tonal drones and looped soundscapes transmitted via
loudspeaker arrays to induce unease or disrupt sleep cycles.
The U.S. Office of Strategic Services (OSS) documented early tests in which looped
mechanical noises were used to mask troop movements while simultaneously
producing low-grade cognitive disorientation. Similarly, Japanese forces reportedly
employed continuous percussion rhythms to unsettle prisoners, a tactic later studied in
postwar military psychology programs.
By the 1950s–1960s, Cold War research expanded into subsonic and ultrasonic
domains. Soviet infrasonic programs under Gavreau’s influence investigated the
destabilizing effects of low-frequency drones on cardiovascular and vestibular systems.
U.S. Naval and Air Force labs explored binaural beat entrainment as both an alertness
enhancement tool for pilots and a potential disorientation mechanism against
adversaries.
The psychoacoustic properties of phase interference became a subject of intense
classified interest when it was observed that layered repetitive patterns could produce
unpredictable perceptual “ghost rhythms,” sometimes causing involuntary motor
synchronization in test subjects — a potential vulnerability in battlefield coordination.
Scientific milestones relevant to military application:
● 1930s–40s: Research into the threshold of discomfort and loudness perception
by Fletcher and Munson established baseline curves still used in tactical acoustic
planning.
● WWII: British “Black Propaganda” units broadcast distorted music and artificial
battlefield sounds to enemy lines; the U.S. Army explored “sound camouflage” to
mask troop movement.
● 1950s: Soviet and U.S. laboratories investigated infrasonic (< 20 Hz) exposure,
finding associations with unease, nausea, and reduced concentration—later
confirmed in controlled psychoacoustic trials.
● 1960s–70s: Cognitive psychology began to model auditory pattern recognition,
phase perception, and adaptation effects—laying the groundwork for modern
loop/dronal warfare concepts.
1.4 History of Modern Development — Composers, Artists, and Scientific Context
The modern era of psychoacoustic exploration in a musical context can be traced
through a series of pivotal figures, each working in different cultural and technological
settings. Below is the chronological sequence, along with the scientific background that
illuminates their contributions to the field.
Igor Stravinsky (1913–1920s)
Stravinsky’s early 20th-century work, particularly The Rite of Spring (1913), introduced
repetitive rhythmic stratification and irregular metric cycles into Western concert music.
While not drone-based, the motoric persistence and predictive dissonance of these
rhythmic blocks engage auditory cortex pattern-recognition loops in ways later
confirmed to alter temporal perception. Contemporary research by Henning (1904) on
rhythm perception provided early evidence of physiological synchronization to external
pulse. In the 1910s and 1920s, experimental psychologists such as Carl Seashore
were developing early models of rhythmic perception, noting that high-intensity,
irregular-but-repetitive rhythms could shift attention and alter perceived time duration.
Research on auditory chunking (Miller, 1956) and expectancy violation (Huron, 2006)
provides a post-hoc framework for understanding the heightened tension in Stravinsky’s
ostinati.
Edgard Varèse (1920s–1950s)
Varèse’s fascination with pure tone blocks and siren glissandi (Ionisation, 1931) aligns
with early studies on continuous pitch motion and its ability to disrupt tonal anchoring
(Deutsch, 1980). His work parallels the 1930s–40s Bell Labs studies on critical band
masking and the psychological fatigue induced by broadband noise exposure. His later
embrace of electronic instruments anticipated laboratory research into auditory scene
analysis and the effects of frequency sweeps on attention redirection. Varèse’s
exploration of sirens and sustained electronic tones in works like Ionisation paralleled
emerging research on auditory fatigue and the destabilizing effects of pure tones on
spatial orientation (Stevens & Davis, 1938). Sustained high-density spectra are known
to accelerate auditory adaptation, reducing situational awareness—a fact later
weaponized in high-noise battlefield conditions.
Anton Webern (1930s–1940s)
Webern’s extreme use of silence and pointillistic tone events (Symphony Op. 21, 1928)
parallels psychoacoustic research on temporal masking and auditory gap detection
thresholds. Webern’s highly concentrated miniatures, though brief, utilized tone color
melodies (Klangfarbenmelodie) and carefully spaced intervals to maximize the
perceptual weight of each sound. Research in this era (Békésy, 1928) on auditory
masking and temporal resolution revealed mechanisms by which sparse, isolated tones
could heighten the perceptual salience of sustained sounds in other registers. Research
in the 1930s by Harvey Fletcher and E.C. Wente showed that the brain can “fill in”
missing sound elements if spectral cues are maintained. The sparseness in Webern’s
music exploits the brain’s tendency to “fill in” missing sound events — a phenomenon
that can induce illusory continuity effects (Miller & Licklider, 1950). The psychoacoustic
relevance lies in his manipulation of temporal sparsity—forcing the listener’s predictive
mechanisms to work harder, a condition known to enhance illusory continuity perception
(Warren et al., 1972).
Giacinto Scelsi (1950s–1980s)
Scelsi’s sustained-tone works (Quattro Pezzi su una nota sola, 1959) explore the
microstructure of a single pitch. Scelsi’s focus on single notes and microtonal inflections
directly engaged overtone perception and beating phenomena. These pieces align with
research on cochlear microphonic adaptation and overtone fusion, wherein slowly
shifting spectra within a fixed fundamental produce perceptual richness without
harmonic movement. In the 1950s and 1960s, psychoacoustic research (Plomp &
Levelt, 1965) clarified how roughness and beating between close partials create
emotional valence shifts—ranging from tension to serenity. Scelsi’s control of
slow-beating partials mirrors methods used to either calm or destabilize listeners in
controlled acoustic environments. Military interest in Scelsi’s approach centered on the
psychological persistence of single-tone exposure and its trance-inducing potential.
This period saw advancements in understanding cochlear microphonics and the
brainstem’s role in pitch discrimination (Rose et al., 1962).
Krzysztof Penderecki (1960s)
Penderecki’s tone clusters (Threnody for the Victims of Hiroshima, 1960) produce
critical-band roughness, a psychoacoustic condition wherein multiple close frequencies
excite overlapping cochlear regions, creating tension and sensory overload. Studies in
the early 1960s (Zwicker, Fastl) quantified the spectral masking and temporal
dissonance such textures produce. Studies on roughness perception (Plomp & Levelt,
1965) clarify why Penderecki’s dense textures elicit visceral unease. Similarly, research
into sensory overload, autonomic arousal, and the startle reflex in relation to dissonant
spectra (Gatchel & Prokasy, 1968) informs this interpretation.Prolonged exposure has
been shown to induce heightened anxiety and confusion, particularly when the
spectrum contains inharmonic partials that resist tonal anchoring.
Steve Reich (1960s–1970s)
Reich’s phase music (Piano Phase, 1967) directly embodies phase interference
principles. His work anticipated laboratory findings that slowly shifting phase
relationships between identical patterns can produce emergent “ghost rhythms” and
induce temporal hallucinations (Bregman, 1978) and hemispheric synchronization
(Oster, 1973).
Robert Fripp (1970s–1990s)
Fripp’s “Frippertronics” — dual-reel tape delay looping — created continuously evolving
drones with overlapping phrase cycles. Research in the late 1960s–70s into echoic
memory (Darwin, Turvey, & Crowder, 1972) found that short-term auditory storage
interacts with ongoing sound in ways that can enhance immersion and reduce the
listener’s perception of discrete time intervals. Fripp’s loops effectively extend the
auditory present, a principle also useful in distraction or orientation-disruption
applications. These textures generate perceptual blending effects similar to those
observed in studies of auditory stream fusion and entrainment decay (Zatorre & Belin,
2001) and temporal integration windows in auditory cortex (Cowan, 1984).Layered
delays created temporal smearing—blurring the onset of new events into the decay of
old ones.
Manuel Göttsching /Ash Ra (1970s - 1980s)
Göttsching’s E2–E4 (1984) is a long-form minimalist piece sustained almost entirely on
looping motifs and subtle harmonic color shifts. This has been shown to induce trances
via minimal harmonic movement and stable rhythmic frameworks, correlating with EEG
studies of repetitive-music-induced alpha coherence (Flohr, 1989). From a
psychoacoustic standpoint, it exploits low attentional load repetition to induce a relaxed
vigilance state — a condition quantified in vigilance decrement studies (Parasuraman,
1979). Studies of flow states and alpha–theta entrainment (Gruzelier, 2009) show that
moderately complex, repetitive stimuli can shift brain activity toward patterns associated
with meditative absorption. Göttsching’s balance of constancy and evolution is a
textbook case for sustaining these states over operationally useful time spans.
Boards of Canada (1990s–2000s)
This duo employs detuned loops, tape warble, low-fidelity drones and looping motifs to
create spectral instability and temporal smearing that evoke nostalgia and subtle
unease. The detuning produces slow beat frequencies, while the degraded
high-frequency content simulates aged media—engaging memory systems differently
than “clean” audio. Such qualities mirror research on degraded auditory cues and
memory recall distortion (Lehmann & Seufert, 1999), relevant in psychological
disorientation contexts. Research on context-dependent memory (Godden & Baddeley,
1975) and affective conditioning indicates that such spectral cues can trigger
autobiographical recall or a sense of temporal dislocation. The effects of degraded
timbres, and cyclic motifs aligns with research into memory-triggered emotional
response via timbral nostalgia cues (Janata et al., 2002). In tactical applications, this
can be used to bias mood states, evoke familiarity, or induce low-level cognitive
dissonance.
Sunn O))) (2000s–present)
Sunn O)))’s ultra-low-frequency drones directly engage vestibular as well as auditory
systems, activating subcortical vibrotactile and vestibular arousal pathways, shown in
research on infrasonic effects on mood and physiological stress markers (Tandy &
Lawrence, 1998). Studies in infrasonic perception (Leventhall, 2007) confirm that
sustained sub-20 Hz components can induce anxiety, altered breathing, and even mild
vertigo — effects with obvious tactical implications. Sustained low-frequency pressure
waves engage the autonomic nervous system, increasing heart rate variability and
galvanic skin response—effects potentially deployable in crowd control or deterrence.
2. Theory of Sustained Tones and
Repetitive Musical Structures
2.1 Acoustic and Neurophysiological Foundations
Sustained tones and repetitive musical structures derive their psychoacoustic potency
from fundamental properties of the human auditory system, many of which evolved for
survival rather than artistic appreciation. The cochlea, a spiral-shaped organ in the inner
ear, functions as a frequency analyzer — decomposing incoming sound into its
component frequencies via the basilar membrane’s tonotopic organization.
A single sustained tone excites a narrow region of the basilar membrane. Over time,
neural adaptation reduces firing rates of auditory nerve fibers tuned to that frequency,
altering the subjective timbre and making overtones or environmental sounds more
perceptible. This spectral shift in awareness is central to trance induction: as the
primary stimulus “fades” perceptually, the brain’s attention is freed to wander while still
being anchored to a constant sonic reference.
In repetitive structures, temporal regularity entrains neural oscillators in the auditory
cortex and motor planning areas. This entrainment is mediated by
cortico-striatal-thalamo-cortical loops, and it can operate at multiple metrical levels
simultaneously. The listener’s internal model of timing adjusts to match the external
periodicity, reducing prediction error — a phenomenon quantified in predictive coding
models of auditory processing (Friston, 2005).
2.2 Overtones and Harmonic Spectrum Effects
Overtones, whether harmonic (integer multiples of the fundamental) or inharmonic,
contribute significantly to the perceived character of sustained sounds. Psychoacoustic
studies have demonstrated that spectral centroid (a measure of brightness) directly
influences emotional valence judgments: higher centroid tones are more likely to be
perceived as tense or alerting, while lower centroid tones evoke calm or ominous
impressions (Sethares, 2005).
The missing fundamental effect — the perception of a pitch at the greatest common
divisor of a harmonic series even when the fundamental frequency is absent — is
relevant in both music and military applications. In noisy or degraded transmission
environments, the brain’s pitch extraction mechanisms can still lock onto an implied
tonal center, allowing a drone’s influence to persist even if its physical representation is
masked by environmental noise or countermeasures.
● Critical bands: Plomp & Levelt (1965) showed that when two partials fall within
the same critical band (~1⁄3 octave), beating and roughness occur, eliciting
tension and heightened alertness.
● Harmonicity vs. inharmonicity: Terhardt (1974) demonstrated that harmonic
spectra are perceived as stable and soothing, while inharmonic spectra resist
tonal anchoring, increasing perceptual uncertainty.
● Sustained tones with slight detuning can induce emotional instability or mild
anxiety.
● Pure harmonic stacks can promote calm and trust, useful in entrainment or
conditioning scenarios.
2.3 Phase Interference and Temporal Perception
When two tones of similar but not identical frequency are presented simultaneously,
their interaction produces beats — amplitude fluctuations at the difference frequency. At
low difference frequencies (≤ 10 Hz), these beats can entrain brainwave patterns in the
alpha (8–12 Hz) or theta (4–8 Hz) ranges, states associated with relaxed alertness or
meditative trance.
At slightly larger frequency separations, the auditory system perceives a shimmering or
pulsing effect known as roughness, a sensation arising from the competition between
overlapping critical bands on the basilar membrane (Plomp & Levelt, 1965). This
roughness is inherently aversive for many listeners and can be exploited for
destabilization in psychological operations.
In complex repetitive structures, slow phase shifts between multiple patterns produce
temporal hallucinations — the perception of rhythms, melodies, or accents not
physically present in the stimulus. Such illusory patterns can distract attention, alter time
perception, and impair cognitive task performance, especially in sustained exposure
scenarios.
● Studies of binaural beats (Oster, 1973) show that when two slightly different
tones are presented separately to each ear, the brain perceives an illusory third
“beat” frequency corresponding to their difference. This can entrain neural
oscillations toward alpha (relaxation) or theta (hypnosis) bands.
● Amplitude modulation and phase cancellation can cause subtle rhythmic pulses
within sustained tones, altering attention and perceived motion in the sound field.
● Binaural and monaural beat induction can be used to modulate alertness,
suppress resistance, or induce trance states without overt rhythmic content.
● Moving interference fields can disorient targets in a space through shifting
loudness zones.
2.4 Neuro-Rhythmic Entrainment and Cognitive State Modulation
The phenomenon of neural entrainment describes the synchronization of endogenous
neural oscillations to external rhythmic stimuli. This is not limited to the auditory cortex
— subcortical structures such as the inferior colliculus and reticular formation are also
sensitive to periodicity, enabling rhythmic sound to influence arousal, vigilance, and
motor coordination.
● High-frequency rhythmic stimuli (> 12 Hz) can enhance cortical excitability and
alertness.
● Low-frequency stimuli (< 8 Hz) tend to induce relaxation, drowsiness, or
trance-like absorption.
From a tactical perspective, the capacity to manipulate opponent vigilance states
without overt semantic content makes sustained tones and repetitive structures
particularly valuable. The listener may remain unaware of the physiological entrainment,
interpreting the altered state as fatigue, boredom, or ambient influence rather than
deliberate conditioning.
● Large-scale research (Nozaradan et al., 2011) confirmed that the brain’s motor
system entrains to musical pulse even without overt movement.
● EEG phase-locking studies show increased alpha or theta power during
repetitive low-tempo rhythmic exposure.
● Steady rhythmic pulses at specific tempos can facilitate hypnotic induction or
group synchronization.
● Slight disruption of rhythmic regularity after entrainment can provoke heightened
suggestibility.
2.5 Emotional Valence and Conditioning
Psychoacoustic conditioning exploits the fact that repetition strengthens associative
learning between a stimulus and an emotional response. A sustained tone or repeating
pattern paired with a particular emotional or situational context can become a
conditioned auditory trigger.
For example:
● A specific drone frequency played during stressful events can later induce
anxiety even in neutral settings.
● Conversely, a repetitive ambient loop paired with positive reinforcement can
generate calming associations.
These mechanisms are well-documented in Pavlovian auditory conditioning research
(Bouton, 2007) and have direct relevance for both psychological operations and
protective countermeasures.
2.6 Psychoacoustic Vulnerabilities and Protective Factors
While the human auditory system is highly adaptive, it is not immune to long-term
modulation by repetitive or sustained sound exposure. Potential vulnerabilities include:
● Reduced vigilance due to habituation.
● Distorted time perception under entrainment.
● Emotional dysregulation through conditioned associations.
Protective countermeasures involve spectral diversity (frequent timbral changes),
temporal irregularity (syncopation, metric shifts), and masking noise to disrupt tonal
stability. In sensitive operations, dynamic spectral scrambling can prevent hostile tonal
conditioning without requiring high sound levels.
2.7 Auditory Scene Analysis and Perceptual Grouping
Proposed by Bregman (1990), this is the process by which the auditory system
organizes sound into perceptually distinct objects or “streams.”
● Listeners group sounds by similarity, continuity, and temporal proximity. Gradual
transformations—like Reich’s phase processes—force continual regrouping,
extending attentional engagement without abrupt change.
● Overlapping harmonic and noise elements can fuse into a perceptually single
“wall of sound,” obscuring source identification.
● Used in masking communications or embedding subliminal cues.
● Can prolong focus on a sonic environment while inhibiting conscious analysis of
its structure.
2.8 Temporal Smearing and Echoic Memory Manipulation
Temporal smearing occurs when sound reflections, delays, or loops blur the distinction
between successive events. Echoic memory stores these overlapping sounds for ~2–4
seconds, creating a fused auditory image.
● Darwin, Turvey, & Crowder (1972) demonstrated that delayed repetitions can
overwrite or blend with the original sound in memory.
● This effect is enhanced in reverberant spaces or with tape/digital loop systems
like Frippertronics.
● Reduces the ability to time events accurately, potentially impairing coordination or
perception of sequence.
● Can deepen immersion in continuous sonic environments, promoting passive
listening states.
2.9 Infrasound and Low-Frequency Resonance
Infrasound refers to frequencies below ~20 Hz, often perceived through tactile or
vestibular sensation rather than hearing.
● Tandy & Lawrence (1998) linked infrasound exposure (~17 Hz) to sensations of
dread, disorientation, and visual disturbances.
● Gavreau’s work in the 1960s on infrasound “cannons” showed that sustained
low-frequency pressure waves can induce nausea or panic.
● Effective in crowd dispersal, psychological intimidation, or inducing physiological
discomfort.
● May act synergistically with visual or narrative cues to amplify emotional impact.
2.10 Nostalgia and Memory Priming through Timbre Degradation
Spectral cues resembling older recording technologies (tape hiss, wow/flutter,
bandwidth limits) trigger associative memory systems differently than pristine
recordings.
● Godden & Baddeley (1975) demonstrated context-dependent recall: matching
environmental cues enhance memory retrieval.
● Zatorre & Halpern (1993) showed that imagined music recruits similar neural
pathways as heard music—suggesting degraded timbres can “activate” personal
past auditory imagery.
● Used for emotional priming before persuasive communication.
● Can evoke familiarity or vulnerability, lowering resistance to influence.
3. Applications in Psychological Warfare
3.1 Historical Precedents and Tactical Context
The use of sustained tones and repetitive musical figures in military and paramilitary
operations predates the formal science of psychoacoustics. From the horn blasts of
Bronze Age warfare to the drone-based shamanic ceremonies of nomadic tribes, sound
has been employed to shape mental states at both the individual and collective level.
During the 20th century, advances in recording, amplification, and transmission
technology enabled the deployment of complex psychoacoustic strategies over large
areas. Notable instances include:
● WWII-era propaganda broadcasts that embedded steady tonal beds under
speech to manipulate attention and induce passive listening.
● Vietnam-era sound warfare such as Operation Wandering Soul, where repetitive
motifs and drones mimicking funeral rites were broadcast at night to unnerve
opponents.
● Cold War research programs (both U.S. and Soviet) into low-frequency sound
exposure, rhythmic induction, and “infrasound fields” designed for crowd control
or troop disorientation.
The underlying concept remained consistent: repeated or sustained auditory stimuli
could alter arousal, cognition, and emotional regulation without overtly revealing their
influence.
3.2 As Protective Defense
3.2.1 Mechanisms of Efficacy
Defensive deployment of sustained tones and loops aims to stabilize the listener’s
cognitive state, creating resilience against adversarial attempts at auditory conditioning
or psychological manipulation.
Key mechanisms include:
● Auditory Anchoring: A familiar drone or loop can act as a perceptual reference
point, reducing the effectiveness of foreign or disruptive sound stimuli.
● Cognitive Load Saturation: By occupying the auditory processing system with a
controlled, predictable signal, hostile sonic content is partially masked or
cognitively deprioritized.
● Physiological Entrainment to Desired States: Defensive tones can be tuned to
frequencies that promote alertness during potential disorientation attempts, or
calm during anticipated panic induction.
3.2.2 Operational Techniques
● Use of broadband harmonic drones incorporating beneficial overtone structures
to counteract tonal masking attacks.
● Strategic deployment of phase-shifted loops to nullify opponent beat induction or
illusory rhythm creation.
● Spectral camouflage — embedding defensive tones in environmental noise
(machinery hum, HVAC resonance) to maintain continuous influence without
overt presence.
3.2.3 Limitations and Risks
● Prolonged exposure to any fixed tonal environment can produce habituation,
reducing protective effects over time.
● If improperly tuned, defensive drones may inadvertently entrain the listener to a
state that is less operationally advantageous (e.g., mild drowsiness).
● In contested environments, defensive sound sources may be detected and
co-opted by adversarial forces.
3.3 As Tactical Offense
3.3.1 Mechanisms of Efficacy
Offensive use of psychoacoustic repetition exploits vulnerabilities in neural prediction
systems and limbic responses to create discomfort, impair task performance, or induce
disorientation.
Primary offensive strategies include:
● Temporal Disruption: Introducing slow phase drift between multiple loops to
generate perceptual uncertainty about tempo and time passage.
● Spectral Fatigue: Sustained tones within sensitive auditory bands (2–4 kHz) that
induce discomfort while avoiding immediate pain thresholds.
● Associative Conditioning: Pairing drones with negative events to create lasting
aversive triggers in the target population.
Scientific literature on auditory salience and vigilance decrements (Warm,
Parasuraman, Matthews, 2008) supports the idea that continuous low-level auditory
demand can degrade situational awareness, particularly in high-stakes environments.
3.3.2 Operational Techniques
● Multi-Layered Loops: Stacking repetitive elements of differing cycle lengths to
produce emergent complexity and cognitive overload.
● Psychoacoustic Camouflage: Embedding dissonant micro-intervals or detuned
layers to create unconscious tension.
● Dynamic Modulation: Gradual frequency or amplitude shifts below conscious
detection thresholds to destabilize the target’s perceptual adaptation.
3.3.3 Limitations and Risks
● Overuse can lead to target desensitization, requiring constant adaptation of
material.
● Effects may vary significantly across individuals depending on cultural and
personal musical exposure.
● In certain contexts, unintended resonance with environmental structures can
amplify or nullify intended effects.
3.4 Combined Defensive and Offensive Scenarios
In modern operations, it is increasingly common for both defensive and offensive sonic
strategies to operate simultaneously within the same acoustic space. In such cases,
phase-domain tactics become crucial — deliberately synchronizing or desynchronizing
sonic fields to either reinforce or cancel each other’s influence.
Examples include:
● Urban peacekeeping operations where protective ambient sound masking is
deployed in civilian areas while targeted psychoacoustic disruption is directed
toward hostile actors.
● Electronic counter-countermeasures in which protective drones are modulated to
disrupt opponent beat-induction loops.
4. Summary and Conclusions
4.1 Summary of Findings
This review describes the substantial corpus of evidence that demonstrates sustained
tones and repetitive musical structures exert measurable psychoacoustic effects with
both protective and offensive utility in the context of psychological warfare.
Key observations include:
1. Physiological Entrainment:
Sustained or repeating signals can synchronize neural oscillations to desired
tempos, modulating arousal and attention. This effect can be leveraged to
promote alertness, reduce anxiety, or induce confusion.
2. Overtone and Harmonic Influence:
Carefully selected harmonic structures — particularly those with prominent
low-order overtones — can create stabilizing or destabilizing sensations in
listeners, depending on deployment.
3. Phase Interference as a Tactical Tool:
Multiple looping phrases of differing lengths or slight detuning produce evolving
interference patterns. These patterns can evoke altered temporal perception,
disorientation, or trance-like focus.
4. Historical Precedent and Scientific Correlation:
The lineage from early 20th-century composers (Stravinsky, Webern, Varèse)
through modern practitioners (Reich, Fripp, Göttsching, Sunn O))) and others)
demonstrates a continuous refinement of these techniques, paralleled by
advancements in psychoacoustic science.
5. Dual-Use Potential:
The same tonal strategies capable of inducing disorientation in adversaries can
be reconfigured to provide mental anchoring and resilience against sonic
manipulation.
4.2 Tactical Implications
The findings strongly suggest that acoustic domain operations deserve parity with
visual, electromagnetic, and information-domain tactics in strategic planning. Given the
low logistical footprint of sustained-tone deployment (relative to visual or kinetic
systems), psychoacoustic measures offer a cost-effective and adaptable addition to field
operations.
Defensively, harmonic drones and controlled repetition can form a cognitive shield,
reducing susceptibility to auditory suggestion, propaganda, or rhythmic entrainment by
adversaries. Offensively, asynchronous loops, dissonant overtones, and phase-shift
patterns can disrupt group coordination, degrade morale, and impair fine motor
performance.
4.3 Recommendations for Further Research
1. Expanded Cross-Cultural Testing:
Psychoacoustic responses are influenced by cultural conditioning; trials across
varied musical traditions will improve reliability of tactical deployment.
2. Integration with Neurophysiological Monitoring:
Real-time EEG and heart-rate variability monitoring during loop/drone exposure
will enable closed-loop adjustment of sonic parameters for maximum effect.
3. Investigation of Sub-Audible and Supra-Audible Domains:
Further study into infrasonic and ultrasonic repetition patterns may yield
additional tactical channels that bypass conscious auditory filtering.
4. Long-Term Exposure Studies:
Understanding habituation thresholds and potential adverse effects is essential
for sustained defensive use in occupied or contested zones.
4.4 Final Conclusion
The convergence of musicology, acoustic engineering, and psychological operations
research now makes it possible to apply the subtle art of sustained tones and repetition
as a scientifically grounded tactical discipline.
Whether as a stabilizing field for friendly forces or a disorienting field for hostile actors,
the principles outlined herein provide the basis for immediate field trials and eventual
doctrinal integration.
Field Applications Development Group, Defense Technologies Division
Classified – For Authorized Distribution Only
As some fellow reviewers have stated before me, 'Between Flesh and
Divine' is a
masterpiece of the prog genre, as well as Asia Minor's top achievement.
This album is one
of the best things that came out of France (though 3 quarters of the
band were actually
Turkish) in the symphonic prog area. As quartet now, the fourth member
Robert Kempler
handled the duties of bass player and keyboardist, which gave the band
the opportunity
to expand their sonic potential with a more prominent addition of
synthesizers, organ,
pianos, and even occasional layers of mellotron - all this in 1980! Of
course, the electric
lead guitar and the flute are still the major features in the
instrumental passages, being in
charge of the solos and the main melodic lines. Beltrami's drumming is
still as polished and
energetic as on the band's debut album, displaying his jazzy vein under
the guise of a rock-
oriented attitude. The sound production is more refined, which makes
every instrument
show itself clearly amidst the band's overall sound. The contrast
between the strong
passages and the soft ones is handled more naturally, which allows the
band to go deeper
into their Camel-esque explorations, without letting go of their
penchant for Asian-based
exotic textures. The repertoire has a somewhat accentuated tendecy
towards the
creation of serene ambiences, locating the rockier passages in the shape
of gently
incerpted interludes or preambles. Tracks 1, 2 and 4 are the best
examples of this clever
arrangement strategy, and may I add that I consider them their best
tracks ever,
specially 'Dedicace', which is catchy, yet keeping a typically
progressive
sophistication. 'Nightwind' kicks off on a vibrant ethnic mood,
ultimately leading to a main body set on the standard of spacey-driven
symphonic rock, not unlike Pulsar or "Moon Madness"-era Camel. 'Northern
Lights' states a more pronunced atmosphere of introspection, generally
speaking, while the aforementioned 'Dedicace' brings a solid dynamics
that fuses the heritages of Pulsar, Focus and Pink Floyd in a sort of
way that only teh guys from Asia Minor can. 'Boundless' is a beautiful
ballad, a not too long passage of melancholy. That same melancholy
resurfaces in a more eerie context during the almost 8 minutes of 'Lost
in a Dream Yell': the intensity incarnated in the extended flute solo is
like an evocative dream made of musical matter. You have hear it to
believe it... It is long but never tiring, it bears a free-flight
attitude yet it never gets meandering; the eerie keyboard layers sustain
the overall mood quite effectively, with the guitar arpeggios and
moderately energetic drumming filling the source of tightness. Finally,
'Dreadful Memories' is nothing but a jam construed from a simple chord
progression on guitar, with the bass and drums following, and an
increasing number of keyboard layers subtly being summoned in: its
abrupt ending makes it the perfect coda for a perfect album. I just wish
it wasn't so short, or at least, that the album as a whole would last a
bit longer thatn it actually does. It wouldn't take long before the
bloody blade of 'musical differences' beheaded Asia Minor's career,
while they were preparing material for a following album that was never
to be. 
By the late 1970s and early 1980s, even prog groups that had attained some level of success - ie made a living
from their releases and live performances - were leaving the industry, dispatched in a fit of expletives by the
arena rock, punk and new wave movements while reflexive critics hailed the long overdue demise of the genre.
Well, history has been lenient in the intervening decades and many of those artists have reformed for at least an
album or two if not a more extended run. Even more miraculous is the return of groups who, by combination
of poor timing and lack of promotion, never even managed cult status at the time. Such is the case with ASIA
MINOR, a France based Turkish act, who issued two albums around the turn of the 1980s, and sadly had to leave
this dream behind in favor of a proper career.
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