Auditory Illusion Research Articles

Stonehenge-like auditory illusion evoked by interference pattern

Blindfolded participants hearing an interference pattern attributed the dead zones to the presence of acoustic obstructions in an arrangement reminiscent of Stonehenge. Without prior mention of interference or Stonehenge, participants were brought blindfolded to an open field with two English flutes atop thin 1 m tall wooden stands 2 m apart, connected via tubing to an air pump, giving a sustained pitch of C#5 (1 100 Hz). One by one, participants were led blindfolded in a 7.6 m radius circle around the pair of flutes. Afterward, faced away from the setup, they were instructed to remove blindfolds and independently “draw and describe what you thought was between you and the noise.” Although there actually were no physical obstacles, the resulting drawings from all three participants represented arrangements of objects having many characteristics in common with Stonehenge; verbal descriptions included “pillars,” “solid objects,” “openings,” “tall vertical slats.” These pilot results demonstrate regions of low sound intensity due to destructive interference of sound waves from musical instruments can be misperceived as an auditory illusion of acoustic shadows cast by a ring of large obstructions. Measurements of acoustic shadows radiating out from Stonehenge are consistent with the hypothesis that interference patterns served as blueprints for the design.

Octave illusion elicited by overlapping narrowband noises

The octave or Deutsch illusion occurs when two tones, separated by about one octave, are presented simultaneously but alternating between ears, such that when the low tone is presented to the left ear the high tone is presented to the right ear and vice versa. Most subjects hear a single tone that alternates both between ears and in pitch; i.e., they hear a low pitched tone in one ear alternating with a high pitched tone in the other ear. The present study examined whether the illusion can be elicited by aperiodic signals consisting of low-frequency band-pass filtered noises with overlapping spectra. The amount of spectral overlap was held constant, but the high- and low-frequency content of the signals was systematically varied. The majority of subjects perceived an auditory illusion in terms of a dominant ear for pitch and lateralization by frequency, as proposed by Deutsch [(1975a) Sci. Am. 233, 92-104]. Furthermore, the salience of the illusion increased as the high frequency of the content in the signal increased. Since no harmonics were present in the stimuli, it is highly unlikely that this illusion is perceived on the basis of binaural diplacusis or harmonic binaural fusion.

Cerebral Venous Sinus Thrombosis Presenting With Auditory Hallucinations and Illusions

Cerebral venous sinus thrombosis may present with seizures or neuropsychiatric symptoms, but does not typically present with hallucinations. We present a case of venous thrombosis of the right sigmoid and transverse sinuses that presented with auditory hallucinations and illusions. We describe a 45-year-old woman with a history of myasthenia gravis, stable on oral prednisone and monthly intravenous immunoglobulin infusions, who started on a progesterone/estrogen combination contraceptive pill for menorrhagia 3 weeks before admission and presented with symptoms of headache, fever, and auditory hallucinations and illusions. The patient's cerebrospinal fluid showed lymphocytic pleocytosis. Two electroencephalograms showed significant right temporal lobe slowing. Magnetic resonance venogram of the brain showed venous sinus thrombosis of the right sigmoid and transverse sinuses. Magnetic resonance imaging showed a cortical venous infarct in the right middle temporal gyrus. The patient's auditory hallucinations and illusions resolved spontaneously weeks after presentation. This case suggests that auditory hallucinations and illusions should be added to the already broad spectrum of presenting features of cerebral venous sinus thrombosis. The nondominant right middle temporal gyrus may play a role in such auditory hallucinations.

Individual Differences in Sound-in-Noise Perception Are Related to the Strength of Short-Latency Neural Responses to Noise

Important sounds can be easily missed or misidentified in the presence of extraneous noise. We describe an auditory illusion in which a continuous ongoing tone becomes inaudible during a brief, non-masking noise burst more than one octave away, which is unexpected given the frequency resolution of human hearing. Participants strongly susceptible to this illusory discontinuity did not perceive illusory auditory continuity (in which a sound subjectively continues during a burst of masking noise) when the noises were short, yet did so at longer noise durations. Participants who were not prone to illusory discontinuity showed robust early electroencephalographic responses at 40–66 ms after noise burst onset, whereas those prone to the illusion lacked these early responses. These data suggest that short-latency neural responses to auditory scene components reflect subsequent individual differences in the parsing of auditory scenes.

Recalibration of the auditory continuity illusion: Sensory and decisional effects

An interrupted sound can be perceived as continuous when noise masks the interruption, creating an illusion of continuity. Recent findings have shown that adaptor sounds preceding an ambiguous target sound can influence listeners’ rating of target continuity. However, it remains unclear whether these aftereffects on perceived continuity influence sensory processes, decisional processes ( i.e., criterion shifts), or both. The present study addressed this question. Results show that the target sound was more likely to be rated as ‘continuous’ when preceded by adaptors that were perceived as clearly discontinuous than when it was preceded by adaptors that were heard (illusorily or veridically) as continuous. Detection-theory analyses indicated that these contrastive aftereffects reflect a combination of sensory and decisional processes. The contrastive sensory aftereffect persisted even when adaptors and targets were presented to opposite ears, suggesting a neural origin in structures that receive binaural inputs. Finally, physically identical but perceptually ambiguous adaptors that were rated as ‘continuous’ induced more reports of target continuity than adaptors that were rated as ‘discontinuous’. This assimilative aftereffect was purely decisional. These findings confirm that judgments of auditory continuity can be influenced by preceding events, and reveal that these aftereffects have both sensory and decisional components.

Strength of the zwicker tone illusion is reflected by induced and evoked brain responses following stimulus offset

Event Abstract Back to Event Strength of the zwicker tone illusion is reflected by induced and evoked brain responses following stimulus offset Sabine Jatzev1*, Ada Tse1 and Nathan Weisz1 1 Universität Konstanz, Germany Studies investigating brain processes giving rise to conscious perception often involve bistable stimuli or illusions, but are mostly restricted to the visual domain (Blake, 2002). The Zwicker tone (ZT) (Zwicker, 1964) is an interesting illusion of the auditory domain that has not been in the center of investigation in this area. The ZT is an auditory afterimage induced by and following to the presentation of notched noise. The perception is a sinusoidal tone with a pitch falling in the frequency range of the noise that is suppressed (Franosch, 2003). The ZT has also been discussed as a theoretical model explaining tinnitus (Norena, 2000). The objective of the current study was to manipulate the ZT illusion in parametrical way, inducing auditory illusions of different loudness. For this white noise with three different notch widths of 0.4, 0.6 and 0.8 or 0.6, 0.8 and 1 octaves were presented and white noise as a control condition. The notch center frequency was chosen according to the subjects ZT detection curves. EEG was measured for thirteen participants from 128 channels. Subjective ratings show a parametric modulation of the participant’s perceived loudness of the ZT according to notch bandwidth. This parametrical modulation is mirrored in EEG measures. Linear trend tests reveal a parametrical enhanced N1 and gamma activity relatively increasing with notch bandwidth and perceived loudness following the offset of the sound, i.e. at the moment of the actual ZT perception. At the same time activity in the alpha band shows the reverse pattern. These EEG patterns might reveal neural processes involved the conscious processing of tones, noise and phenomena in the auditory domain. Keywords: Awareness, EEG Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Consciousness and Awareness Citation: Jatzev S, Tse A and Weisz N (2011). Strength of the zwicker tone illusion is reflected by induced and evoked brain responses following stimulus offset. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00056 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Mrs. Sabine Jatzev, Universität Konstanz, Konstanz, Germany, sabine.jatzev@googlemail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Sabine Jatzev Ada Tse Nathan Weisz Google Sabine Jatzev Ada Tse Nathan Weisz Google Scholar Sabine Jatzev Ada Tse Nathan Weisz PubMed Sabine Jatzev Ada Tse Nathan Weisz Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

A proposed neural mechanism underlying auditory continuity illusions

A numerical thought experiment was conducted to assess whether stimulus-specific, short-term changes in auditory neural responsiveness could explain the formation of auditory objects underlying the auditory continuity illusion. A tonotopic, two-layer feedforward network model with one time constant for synaptic weight augmentation based on firing rate, and an independent time constant for synaptic weight decay was presented with classical continuity illusion stimuli. The results suggest that the continuity illusion could, in principle, be explained by basic, duration-dependent auditory circuit behavior, which could emerge at either early or later stages of processing.

Testing an auditory illusion in frogs: perceptual restoration or sensory bias?

The human auditory system perceptually restores short deleted segments of speech and other sounds (e.g. tones) when the resulting silent gaps are filled by a potential masking noise. When this phenomenon, known as 'auditory induction', occurs, listeners experience the illusion of hearing an ongoing sound continuing through the interrupting noise even though the perceived sound is not physically present. Such illusions suggest that a key function of the auditory system is to allow listeners to perceive complete auditory objects with incomplete acoustic information, as may often be the case in multisource acoustic environments. At present, however, we know little about the possible functions of auditory induction in the sound-mediated behaviours of animals. The present study used two-choice phonotaxis experiments to test the hypothesis that female grey treefrogs, Hyla chrysoscelis, experience the illusory perceptual restoration of discrete pulses in the male advertisement call when pulses are deleted and replaced by a potential masking noise. While added noise restored some attractiveness to calls with missing pulses, there was little evidence to suggest that the frogs actually experienced the illusion of perceiving the missing pulses. Instead, the added noise appeared to function as an acoustic appendage that made some calls more attractive than others as a result of sensory biases, the expression of which depended on the temporal order and acoustic structure of the added appendages.

Magnetic Evoked Responses During An Auditory Illusion

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Auditory illusion explored with MEG

Event Abstract Back to Event Auditory illusion explored with MEG Ken-ichi Ouchi1*, Shinya Kuriki2, Asuka Otsuka3 and Makoto Takahashi1 1 Hokkaido University, Japan 2 Tokyo Denki University, Japan 3 The University of Tokyo, Elekta K.K, Japan Deutsch has shown in her paper (1975) an auditory illusion occurring when dichotic tonal sequences are given to listeners in both ascending and descending forms, in a way that a component of the ascending scale is in one ear, a component of the descending scale is in the other, and vice versa repetitively. Most right handed subjects perceived two streams of “scale illusion” where higher tones in the scale appear exclusively in one ear and other lower tones in the other. Here, we made MEG measurements to examine how the dichotic tones in a scale are represented in the right and left auditory cortices using frequency tagging, in which higher and lower tones were amplitude modulated at distinct frequencies of fH and fL. Steady state MEG responses were separated by FFT into fH and fL components. In some subjects who reported the percept of scale illusion, the amplitudes of fH and fL component of contra- (or ipsi-) and ipsi- (or contra-) lateral responses were altered from the normal relation of contralateral preference. Such increment/decrement of the responses in the auditory cortex to some component-tones in the tonal sequence might be related with the percept of scale illusion.

An Auditory Illusion of Infinite Tempo Change Based on Multiple Temporal Levels

Humans and a few select insect and reptile species synchronise inter-individual behaviour without any time lag by predicting the time of future events rather than reacting to them. This is evident in music performance, dance, and drill. Although repetition of equal time intervals (i.e. isochrony) is the central principle for such prediction, this simple information is used in a flexible and complex way that accommodates both multiples, subdivisions, and gradual changes of intervals. The scope of this flexibility remains largely uncharted, and the underlying mechanisms are a matter for speculation. Here I report an auditory illusion that highlights some aspects of this behaviour and that provides a powerful tool for its future study. A sound pattern is described that affords multiple alternative and concurrent rates of recurrence (temporal levels). An algorithm that systematically controls time intervals and the relative loudness among these levels creates an illusion that the perceived rate speeds up or slows down infinitely. Human participants synchronised hand movements with their perceived rate of events, and exhibited a change in their movement rate that was several times larger than the physical change in the sound pattern. The illusion demonstrates the duality between the external signal and the internal predictive process, such that people's tendency to follow their own subjective pulse overrides the overall properties of the stimulus pattern. Furthermore, accurate synchronisation with sounds separated by more than 8 s demonstrate that multiple temporal levels are employed for facilitating temporal organisation and integration by the human brain. A number of applications of the illusion and the stimulus pattern are suggested.

Short-Latency, Goal-Directed Movements of the Pinnae to Sounds That Produce Auditory Spatial Illusions

The precedence effect (PE) is an auditory spatial illusion whereby two identical sounds presented from two separate locations with a delay between them are perceived as a fused single sound source whose position depends on the value of the delay. By training cats using operant conditioning to look at sound sources, we have previously shown that cats experience the PE similarly to humans. For delays less than +/-400 mus, cats exhibit summing localization, the perception of a "phantom" sound located between the sources. Consistent with localization dominance, for delays from 400 mus to approximately 10 ms, cats orient toward the leading source location only, with little influence of the lagging source. Finally, echo threshold was reached for delays >10 ms, where cats first began to orient to the lagging source. It has been hypothesized by some that the neural mechanisms that produce facets of the PE, such as localization dominance and echo threshold, must likely occur at cortical levels. To test this hypothesis, we measured both pinnae position, which were not under any behavioral constraint, and eye position in cats and found that the pinnae orientations to stimuli that produce each of the three phases of the PE illusion was similar to the gaze responses. Although both eye and pinnae movements behaved in a manner that reflected the PE, because the pinnae moved with strikingly short latencies ( approximately 30 ms), these data suggest a subcortical basis for the PE and that the cortex is not likely to be directly involved.

A test of Gestalt grouping principles in frogs: Auditory illusion or sensory bias?

The study of auditory illusions has been important in elucidating the rules of auditory grouping in humans, which adheres to principles first described by Gestalt psychologists to explain the formation of visual objects. For example, the human auditory system perceptually restores short, deleted segments of speech and other sounds (e.g., tones) when the resulting gaps are filled by a potential masking noise. Results from studies of such illusions suggest that the Gestalt principle of “continuity” allows humans to perceive complete auditory objects in the face of incomplete or degraded acoustic information in the presence of noise. The present study tested the hypothesis that female treefrogs experience the perceptual restoration of discrete pulses in the male sexual advertisement signal when they are deleted and replaced by a potential masking noise. While added noise restored some attractiveness to degraded signals, there was no evidence that the frogs experienced the illusion of perceiving actual pulses that were missing. Instead, the added noise functioned as an acoustic ornament that made some signals more attractive than others as a result of an inherent sensory bias for greater sensory stimulation. Whether such sensory biases themselves adhere to Gestalt principles of auditory grouping remains to be demonstrated.

Phonological features, auditory objects, and illusions

It is argued that speech perception, just like visual perception, relies on a good match between memorized experience and current sensation: when sensation meshes with expectations, listeners believe they perceive ‘real’ linguistic objects in spite of possibly severe variation and degradation in the acoustic signal. Reviews of the acoustic and perceptual correlates of the features [nasal] and [voice] in various speech styles illustrate how multiple perceptual cues to a simple phonological distinction may be dispersed across syllables, and how absence of one or several such cues may be compensated by the presence of others, or by recovery processes that rely on listeners’ knowledge and expectations. Visual illusions are discussed which have apparent parallels with auditory illusions and with well-known aspects of speech perception. These include particular types of physical structure (e.g. abrupt changes, edges), enhancement of properties of a given object by juxtaposed information which either changes the percept of those properties, or else provides a context that changes the percept of what the object is, and influences of familiarity and probability which can be profound enough to fly in the face of contrary sensory evidence. These data are used to support the hypothesis that perceived linguistic units, including distinctive features, are ephemeral (and illusory) ‘auditory objects’, which are created by the listening brain using domain-general processes that underpin meaningful behaviour.

Cortical evoked potentials to an auditory illusion: Binaural beats

To define brain activity corresponding to an auditory illusion of 3 and 6Hz binaural beats in 250Hz or 1000Hz base frequencies, and compare it to the sound onset response. Event-Related Potentials (ERPs) were recorded in response to unmodulated tones of 250 or 1000Hz to one ear and 3 or 6Hz higher to the other, creating an illusion of amplitude modulations (beats) of 3Hz and 6Hz, in base frequencies of 250Hz and 1000Hz. Tones were 2000ms in duration and presented with approximately 1s intervals. Latency, amplitude and source current density estimates of ERP components to tone onset and subsequent beats-evoked oscillations were determined and compared across beat frequencies with both base frequencies. All stimuli evoked tone-onset P(50), N(100) and P(200) components followed by oscillations corresponding to the beat frequency, and a subsequent tone-offset complex. Beats-evoked oscillations were higher in amplitude with the low base frequency and to the low beat frequency. Sources of the beats-evoked oscillations across all stimulus conditions located mostly to left lateral and inferior temporal lobe areas in all stimulus conditions. Onset-evoked components were not different across stimulus conditions; P(50) had significantly different sources than the beats-evoked oscillations; and N(100) and P(200) sources located to the same temporal lobe regions as beats-evoked oscillations, but were bilateral and also included frontal and parietal contributions. Neural activity with slightly different volley frequencies from left and right ear converges and interacts in the central auditory brainstem pathways to generate beats of neural activity to modulate activities in the left temporal lobe, giving rise to the illusion of binaural beats. Cortical potentials recorded to binaural beats are distinct from onset responses. Brain activity corresponding to an auditory illusion of low frequency beats can be recorded from the scalp.

Neural dynamics of speech perception: Phonemic restoration in noise using subsequent context.

Phonemic restoration describes a class of auditory illusions during which broadband noise replacing a deleted phoneme can cause the perceptual restoration of the deleted phoneme. Phonemic restoration exemplifies the brain’s ability to complete and understand speech and language in noisy environments. It also clarifies how both past and future acoustical events can contextually guide completion of a percept that is occluded by noise, and highlights that conscious speech is due to bottom-up and top-down contextual interactions that can operate across hundreds of milliseconds. This work develops a neural model that quantitatively simulates restoration phenomena, including the forward development in time of a conscious speech percept even in cases where future events control how previously presented acoustic events are heard. The model clarifies how acoustic items are stored in short-term working memory, and how they interact reciprocally with unitized representations of item sequences, or list chunks, to generate a resonant wave of activation that embodies the consciously heard percept. Model simulations clarify why the presence of noise is necessary for restoration to occur, and why in the absence of noise a silence gap is perceived. These properties are traced to the brain's ability to rapidly and stably learn language.

The development of music psychology in Britain: A personal perspective.

ABSTRACT-The development of music psychology in Britain over the last few decades is outlined from the personal viewpoint of the author, who was actively involved in research and teaching in the field. The important ideas and influential researchers of the period are described, together with their influence on the author's own research interests. More recent developments are also reviewed showing the great broadening of research activity in the whole subject area. I came into Psychology from a scientific background at a time of rising interest in the questions of perception and cognition. Although a keen amateur musician, I decided to specialize in visual perception, inspired by Richard Gregory (no relation), Fergus Campbell, and Horace Barlow at the University of Cambridge. At that time, in the 1960s, psychological studies on vision still had a valuable role to play in advancing knowledge. However, gradually advances in physiological research seemed to be explaining more and more of the phenomena of visual perception, and there remained much less scope for purely psychological studies. I became interested in another developing field at that time, the idea of cerebral dominance. For normal right-handed people the left cerebral hemisphere seemed to control most speech functions, whilst the right hemisphere seemed more associated with spatial processing. Kimura (1964), using the technique of dichotic listening, had demonstrated that the perception of melody was probably also a right hemisphere function. The idea of this dichotomy, language in the left hemisphere, music in the right, first aroused my interest in music psychology. What about the perception of rhythm? This occurs in both music and in language but is probably more fundamental to music. With a graduate student, Lorna Roberts, we asked listeners to adjust the precise timing of brief auditory stimuli presented alternately to the two ears, and concluded that it was the right hemisphere that was involved in rhythm perception (Gregory, Harriman, & Roberts, 1972). A further study using the technique of delayed auditory feedback on rhythmic tapping again suggested right hemisphere involvement (Roberts & Gregory, 1973). At this time the techniques for presenting precisely controlled auditory stimuli required considerable ingenuity. The experiment requiring regular brief pulses of sound used an audiometer controlled by external logic circuits, and delayed auditory feedback was produced by the delay between the record and playback heads of a tape-recorder. My developing interest in this field led to a study of Deutsch 's (1974) auditory illusion. She reported that alternating 2-note chords, presented with one note to each ear, were usually perceived by righthanded listeners as a sequence of high tones to the right ear and low tones to the left ear. With a colleague, Ian Christensen, we studied this with harmonic and dissonant chords, and also varying the relative intensity of the notes (Christensen & Gregory, 1977). For harmonic chords only a single tone was heard, but where it was heard depended critically on which ear received the louder note. For dissonant chords the two individual notes were more often heard. This supported an alternative study by Efron and Yund (1974), which demonstrated that individuals differ in their ear dominance for pitch perception. I spent a sabbatical year in California working with Robert Efron, William Yund, and also Pierre Divenyi, a talented musician working on language. This improved my knowledge of both the theoretical bases of auditory and musical perception, and of the use of computers to control auditory and musical stimuli. My research during this year also led to studies showing that there was no clear relationship between ear dominance and handedness (Gregory, 1982), and that ear dominance was not simply explained by either attentional bias or by hemispheric specialization in the processing of tonal stimuli (Gregory, Efron, Divenyi, & Yund, 1983). …

Unpredictable interruption can enhance the auditory continuity illusion

It was examined whether the predictability of interruption timing affects the limit of perceiving the continuity illusion. The stimulus consisted of a 500-Hz sinusoidal inducee and a 200-ms, 500-Hz, 1/3-octave noise band inducer, which were alternated repeatedly, with a fixed interval (400 ms) between adjacent inducers (regular condition) or with random intervals (irregular condition). The continuity limit (CL) was measured in terms of the maximum level of the inducee for the illusory continuity to be perceived while maintaining the inducer level at 60 dB SPL. In Experiment 1, the listeners' task was to judge whether the inducee appeared continuous or discontinuous. In Experiment 2, the task was to discriminate illusory and physical continuity in a two-interval forced choice paradigm. In both experiments, the mean CLs in the irregular condition were significantly higher than those in the regular condition. In Experiment 3, when an identical irregular interval pattern was used repeatedly in successive trials, the mean CL gradually declined, and reached the level of the regular condition in approximately 80 trials. These results suggest that unpredictability, not mere irregularity, in interruption timing promotes the continuity illusion, implying the involvement of the short-term plasticity of the auditory system.

Unpleasant auditory illusions and related avoidance behaviour in a child

Auditory aura is a rare symptom in focal epilepsy. It has been described in autosomal dominant partial epilepsy with auditory features, but is, in general, poorly documented. We report on a 7-year-old, right-handed boy, who suffered seizures characterized by positive auditory illusions with verbal and gestural automatisms and noticeable attempts at covering his ears. Clinical evaluation and video-recording of the seizures, confirmed that most of the ictal behavior was deliberately directed at trying to prevent the unpleasant sensations reaching his ears. [Published with video sequences].

The auditory continuity illusion: A parametric investigation and filter model

A sound that is briefly interrupted by a silent gap is perceived as discontinuous. However, when the gap is filled with noise, the sound may be perceived as continuing through the noise. It has been shown that this continuity illusion depends on the masking of the omitted target sound, but the underlying mechanisms have yet to be quantified thoroughly. In this article, we systematically quantify the relation between perceived continuity and the duration, relative power, or notch width of the interrupting broadband noise for interrupted and noninterrupted amplitude-modulated tones at different frequencies. We fitted the psychometric results in order to estimate the range of the noise parameters that induced auditory grouping. To explain our results within a common theoretical framework, we applied a power spectrum model to thedifferent masking resultsand estimated the critical bandwidth of the auditory filter that may be responsible for the continuity illusion. Our results set constraints on the spectral resolution of the mechanisms underlying the continuity illusion and provide a stimulus set that can be readily applied for neurophysiological studies of its neural correlates.