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In this paper, the auditory motion aftereffect (aMAE) was studied, using real moving sound as both the adapting and the test stimulus. The sound was generated by a loudspeaker mounted on a robot arm that was able to move quietly in three-dimensional space. A total of 7 subjects with normal hearing were tested in three experiments. The results from Experiment 1 showed a robust and reliable negative aMAE in all the subjects. After listening to a sound source moving repeatedly to the right, a stationary sound source was perceived to move to the left. The magnitude of the aMAE tended to increase with adapting velocity up to the highest velocity tested (20 degrees/sec). The aftereffect was largest when the adapting and the test stimuli had similar spatial location and frequency content. Offsetting the locations of the adapting and the test stimuli by 20 degrees reduced the size of the effect by about 50%. A similar decline occurred when the frequency of the adapting and the test stimuli differed by one octave. Our results suggest that the human auditory system possesses specialized mechanisms for detecting auditory motion in the spatial domain.

Experiment 1 tested the habituation hypothesis of the Verbal Transformation Effect, an auditory illusion in which a repeating verbal stimulus undergoes perceptual transformation, by varying stimulus dimensions which might be expected to retard habituation. Transformations were found to increase as a function of imagery value and word length, failing to support the habituation hypothesis. Experiment 2, in which transformations were found to vary as a function of number of activated semantic representations of a physically invariant homophone stimulus, provided support for a new dual-process explanation of the Transformation effect, based on spreading activation between cognitive representations.

In four cross-linguistic experiments comparing French and Japanese hearers, we found that the phonotactic properties of Japanese (very reduced set of syllable types) induce Japanese listeners to perceive ``illusory'' vowels inside consonant clusters in VCCV stimuli. In Experiments 1 and 2, we used a continuum of stimuli ranging from no vowel (e.g. ebzo) to a full vowel between the consonants (e.g. ebuzo). Japanese, but not French participants, reported the presence of a vowel [u] between consonants, even in stimuli with no vowel. A speeded ABX discrimination paradigm was used in Experiments 3 and 4, and revealed that Japanese participants had trouble discriminating between VCCV and VCuCV stimuli. French participants, in contrast had problems discriminating items that differ in vowel length (ebuzo vs. ebuuzo), a distinctive contrast in Japanese but not in French. We conclude that models of speech perception have to be revised to account for phonotactically-based assimilations.

Humans and owls localize sounds by detecting the arrival time disparity between the ears. Both species determine the interaural time difference by finding the delay necessary to match the leading signal with the lagging one. This method produces ambiguity with periodic signals, because the two signals can be matched by delaying either one or the other. As predicted, owls localized periodic signals in illusory directions, whereas they always perceived the real source when signal bandwidth exceeded a certain value. This bandwidth also enabled higher-order auditory neurons to discriminate between real and illusory sources.

Humans and cats can localize a sound source accurately if its spectrum is fairly broad and flat, as is typical of most natural sounds. However, if sounds are filtered to reduce the width of the spectrum, they result in illusions of sources that are very different from the actual locations, particularly in the up/down and front/back dimensions. Such illusions reveal that the auditory system relies on specific characteristics of sound spectra to obtain cues for localization. In the auditory cortex of cats, temporal firing patterns of neurons can signal the locations of broad-band sounds. Here we show that such spike patterns systematically mislocalize sounds that have been passed through a narrow-band filter. Both correct and incorrect locations signalled by neurons can be predicted quantitatively by a model of spectral processing that also predicts correct and incorrect localization judgements by human listeners. Similar cortical mechanisms, if present in humans, could underlie human auditory spatial perception.

The illusion as first reported is this: a tonal stimulus of high pitch when presented straight ahead appears to originate above a tonal stimulus lower in pitch. Its actual elevation matters not; your judgment is based on the frequency of the auditory stimulus. The illusion is compelling even when you know that the sound source is fixed in space. The unequivocal conclu- sion is that stimulus frequency has a spatial referent. The first formal study ofwhat has been termed the "spatial characteristics ofauditoryfrequency" was conducted by Pratt (I). He concealed a telephone receiver behind a screen divided into 14 equal parts and numbered accordingly. Five differ- ent tones, ranging in octave steps from 256 to 4096 Hertz (Hz) (Hz being equivalent to cycles per second) , were delivered by the receiver from five different vertical locations in the median sagittal plane—the plane that bisects the head longitudinally. Pratt asked listeners to report the vertical position of each tone, and they reported that the higher pitched sound seemed to come from above, and the lower pitched sound seemed to come from below. Some kind ofstrong associative process must be operating here (2) . We regularly use the words high and low to describe the pitch ofa tone: in musical passages high-pitched tones are light and airy, whereas low- pitched tones are voluminous and massive. Perhaps Pratt's subjects, without consciousness awareness, thought that the 4096 Hz tone originated from near the upper sector of the vertical screen because it had a higher pitch than the other tones. Suzanne Roffler, a graduate student in psychology, and I agreed that this auditory illusion was an interesting problem and decided to devote time to it. We essentially replicated Pratt's study and extended the frequency

Here the problem of the verification of new illusions is addressed. Subtle perceptual illusory experiences can be hard to recognize, meaning that it can be difficult or impossible for an introspecting psychologist to convey a new illusion or verify that other people experience a new illusion without polluting other people's experience by introducing biasing expectations through the very act of describing what the illusory experience might be like. The proposed solution is to offer subjects an array of descriptions of faux illusions that are known to be unexperienceable, along with the new illusion, in order to determine whether naive subjects are uniquely more likely to report an illusory experience for the hypothetical new illusion than for the faux illusions.

Computational auditory scene analysis — modeling the human ability to organize sound mixtures according to their sources — has experienced a rapid evolution from simple implementations of psychoacoustically inspired rules to complex systems able to process demanding real-world sounds. Phenomena such as the continuity illusion and phonemic restoration show that the brain is able to use a wide range of knowledge-based contextual constraints when interpreting obscured or overlapping mixtures: To model such processing, we need architectures that operate by confirming hypotheses about the observations rather than relying on directly extracted descriptions. One such architecture, the 'prediction-driven' approach, is presented along with results from its initial implementation. This architecture can be extended to take advantage of the high-level knowledge implicit in today's speech recognizers by modifying a recognizer to act as one of the 'component models' providing the explanations of the signal mixture. A preliminary investigation indicates the viability of this approach while at the same time raising a number of issues which are discussed. These results point to the conclusion that successful scene analysis must, at every level, exploit abstract knowledge about sound sources.

SummaryA tendency to extract spurious, message-like meaning from meaningless noise was assessed as a risk factor leading to shizophrenia-spectrum disorders by assessing word length of speech illusions elicited by multispeaker babble in 43 people with prodromal symptoms. These individuals were randomised to olanzapinev.placebo groups during year 1 followed by no pharmacological treatment for those with no disorder conversion during year 2. A time-dependent Cox regression analysis of conversion to schizophrenia-spectrum disorder revealed a significant interaction between condition (olanzapinev.no drug) and length of speech illusion, with the latter strongly predicting subsequent conversion during medication-free intervals but not during olanzapine treatment.

Palinacousis, an auditory illusion in which perceived aural sensations persist or recur after the initial acoustic stimulus has ceased,1 may be caused by structural lesions involving the temporal lobe. However, the reported lesions were usually extensive, and detailed imaging tests were rarely performed.2-4 We report a patient with transient palinacousis following discrete temporal lobe intracerebral hemorrhage (ICH). A 67-year-old hypertensive woman suddenly developed language disturbances. On examination the next day, she was alert, and cranial nerves and motor and sensory functions were intact. Her speech was fluent and mixed with frequent paraphasic errors. She showed difficulty in understanding and naming. The Korean version of the Western Aphasia Battery confirmed that she had severe Wernicke-type aphasia (Aphasia Quotient = 27.2/100). Brain MRI showed an acute ICH in the left middle temporal gyrus (figure). Her language disturbances rapidly improved. Three days after the symptom onset, auditory comprehension (0.5/10 to 7.5/10) and repetition (3.1/10 to 6.7/10) considerably improved, but there remained significant naming deficits (0/10 to …

Previously, it was shown that the minimum conditions for the illusion of auditory apparent motion (AAM) depend on stimulus timing but not spatial separation. In the present experiment, the effects of stimulus timing and source separation on the perceived velocity of AAM were examined. Eight listeners estimated the velocity, duration, and distance traveled of AAM, using a no-modulus, magnitude estimation procedure. Four burst durations (25, 50, 100, and 300 msec), 10 stimulus onset asynchronies (SOAs; 30, 40, 50, 60, 70, 80, 90, 100, 110, and 120 msec) and two separations (10 degrees and 40 degrees) were tested. Perceived velocity estimates were related to the total duration (burst duration + SOA) of the stimulus sequence. The effect of separation on velocity was extremely small but statistically significant. These results are similar to those obtained previously on the minimum conditions for AAM. Duration estimates were related only to total duration, but separation estimates were related to both separation and total duration. These results suggest that velocity is possibly a primary dimension of AAM that is independent of source separation.

The effects of frequency differences between the lead and lag stimuli on auditory apparent motion (AAM—the perception of continuous changes in the location of a sound image over time) were examined in two experiments. In experiment 1, three standard frequencies (500, 1000, and 5000 Hz) and three SOAs (40, 60, and 100 ms) were tested. Both standard frequency and stimulus onset asynchrony (SOA) were constant throughout a session. Eleven comparison frequencies were tested within each session, with the range dependent on the standard frequency. At standard frequencies of 500 and 1000 Hz, AAM was heard when the frequencies of the lead and lag stimuli were within 100 Hz of each other. At 5000 Hz, the range of frequencies producing AAM increased with SOA. In experiment 2, two standards (500 and 5000 Hz) were tested with a wider range of SOAs (10–210 ms) varied within a session, and a narrower range of comparison frequencies. Here, comparison frequency was constant throughout a session. At 500 Hz, the SOAs producing AAM did not depend on comparison frequency. At 5000 Hz, the SOAs producing AAM increased with comparison frequency, consistent with Korte's third law of visual apparent motion.

This article introduces ad-hoc synthesis, an approach to designing auditory icons and synthesis algorithms that emphasizes the perception of the sounds by users instead of the analysis of actual sources and sound. We describe two substractive synthesis algorithms for generating and controlling wind and wave sounds in real-time by means of high-level parameters. Even though these sounds are not audiorealistic, they convey information in a non-intrusive way and therefore are suitable for monitoring background activities. These sounds capture the main invariants of the sounds they imitate, enabling users to recognize and understand them easily. We then push the approach further by showing how an auditory illusion, i.e. a sound that does not exist in the real world, can be used to convey the notion of speed in a natural and non-intrusive way.

Several auditory illusions are accounted for by using the event construction model as presented by Nakajima et al. (2000) in order to explain the gap transfer illusion. In this model, the perceptual system detects and processes onsets and offsets of sounds as if they were independent elements. Temporal edges of sounds and their perceptual attributes are combined to construct auditory events obeying the proximity principle in time and frequency. For example, the onset and offset of a Chinese syllable belonging physically to different tones can be combined if close enough in time and frequency. The listener often hears a syllable with a lexical tone resulting from this illusory connection. Illusory attribution of perceptual features also occurs in nonspeech tones. One demonstration where only an offset of a glide is presented shows the mechanism; a very short illusory tone with no physical counterpart is perceived. Probably, the perceptual system looks for an onset to connect with the offset, but fails and ...

The auditory illusory perception “scale illusion” occurs when a tone of ascending scale is presented in one ear, a tone of descending scale is presented simultaneously in the other ear, and vice versa. Most listeners hear illusory percepts of smooth pitch contours of the higher half of the scale in the right ear and the lower half in the left ear. Little is known about neural processes underlying the scale illusion. In this magnetoencephalographic study, we recorded steady-state responses to amplitude-modulated short tones having illusion-inducing pitch sequences, where the sound level of the modulated tones was manipulated to decrease monotonically with increase in pitch. The steady-state responses were decomposed into right- and left-sound components by means of separate modulation frequencies. It was found that the time course of the magnitude of response components of illusion-perceiving listeners was significantly correlated with smooth pitch contour of illusory percepts and that the time course of response components of stimulus-perceiving listeners was significantly correlated with discontinuous pitch contour of stimulus percepts in addition to the contour of illusory percepts. The results suggest that the percept of illusory pitch sequence was represented in the neural activity in or near the primary auditory cortex, i.e., the site of generation of auditory steady-state response, and that perception of scale illusion is maintained by automatic low-level processing.

Object perception is a multimodal task, involving both sight as well as sound to localize objects. Several visual illusions have made use of multi-stable percepts of object direction and location (Necker, 1832; Kayahara, 2003). Here, we created an auditory correlate of such visual illusions that causes differential interpretations of object direction and location, yet with a constant visual input. This quadristable auditory illusion makes use of back-front confusions to give varying perceptions of an object approaching and retracting from the listener. Observers can perceive the sound as traveling: 1) front to back, 2) back to front, 3) coming from and returning to the front, and 4) coming from and returning to the back. To test this illusion, participants sat in a symmetrical, customized chamber with four speakers positioned on the cardinal axes around them and performed several psychophysics experiments where participants were asked to discriminate between 1) sounds really moving between the speakers and 2) the illusion (which is played equally in the front and back speakers and does not move). When asked to discriminate between real and illusory sounds, observers performed at chance. They localized the illusory sound as all different directional possibilities. When asked to rate their confidence in perceiving a sound cued by directional instructions, they gave equal confidence for the real and illusory sounds (despite the illusion having no direction). When rotated 90 degrees, so that the sounds now traveled between the left and right speakers, observers performed at ceiling. These results show the illusion along the front-back axis is not differentiable from truly moving sounds, and is successful in producing directional percepts. Such quadristable auditory illusions open new opportunities in multimodal science, for studying the perceptual, cognitive and neural representation of objects and space, as well as exploring multi-dimensional perceptual awareness.

The precedence effect is well known as one of auditory illusions occurred by using multiple sound sources with similar sound output. When a sound is followed by similar sound separated with relatively short time delay, a single fused sound image is localized at the source position corresponding to the first-arriving sound. This feature is applicable to public address systems, which make audience perceive the sound image different from the actual sound source positions prepared for the system, with some sound reinforcement achieved. In spite of many studies in this phenomenon, the behavior of the precedence effect has been investigated for limited sound source arrangements in laboratory environments like anechoic chamber. On the other hand, this behavior in the ordinary room is not obvious, and it is effective to clarify the difference of the behavior of the precedence effect in anechoic chamber from that in the ordinary room for the application of the precedence effect to the public address system. In this study, the similar sound sources were installed both in the lecture room and in the anechoic chamber, and the behavior of the precedence effect was compared each other with the given time and level difference among sound sources.

In humans, the lateral movement of an acoustic source produces dynamic changes in the relative sound-pressure level and time of arrival of the acoustic wave at the 2 ears. The dynamic nature of these cues is assumed to play an important role in the perception of lateral motion. A phenomenon of auditory motion is reported whose lateral direction and relative velocity may be specified while interaural differences are kept constant. The stimulus producing this percept is a narrowband wave-form whose instantaneous bandwidth is a cosine function of time. This phenomenon is predicted from a model of cross-correlation that estimates the running position of an image from a weighted combination of 2 variables: (a) magnitude of interaural delay, with smaller delays receiving more weight, and (b) consistency of interaural information across frequency.

Publisher Summary This chapter presents three aspects of attention: (1) attention as selection (the cocktail party studies); (2) attention as set (the temporal allocation studies); and (3) attention as organizing the auditory environment (the streaming and auditory illusion studies). The chapter also discusses doubts that could be cast upon some well-known studies that expressed much optimism about the fate of unattended messages, advocating that there is an inherent confounding of attentional selection features in the dichotic paradigm. Good example of a study that explicitly investigated the temporal allocation of attention in a single speech stream is based on Martin's model for rhythmic structure in speech and other behavior, which states that speech elements are hierarchically organized, providing an underlying temporal structure within which elements are related instead of being simply concatenated. The sequences of nine tones have been constructed from a three-tone argument by applying certain rules. A three-tone argument comprised, for instance, the increasing musical tones G4, A4, and B4 from the C major scale. The three-tone argument has been preceded and succeeded by three-tone patterns resulting from one or two higher rules, which yielded melodic strings.

Sheppard-Risset tones are sounds that seem to go up (or down) indefinitely. We have designed an "elevator" sound based on this auditory illusion and have implemented it in the ENO audio system. The sound is synthesized in realtime and can be controlled in real-time through high-level parameters. We have used this sound for audio feedback when scrolling and for monitoring the progress of long system operations.

Trains of 8 binaural clicks, 4 left-ear-leading followed by 4 right-ear-leading, were presented to 14 healthy adults. At interstimulus intervals of less than 120 ms, the subjects mislocalized the sounds, perceiving illusorily that the clicks jumped in equidistant steps from left to right. However, monaural clicks, left-sided followed by right-sided, did not produce a similar effect. The illusion thus has strict neuronal constraints: activation of overlapping neuronal populations in rapid succession. In such conditions the brain integrates sound locations for 100–150 ms and the conscious perception may be delayed by about 500 ms.

The illusion of McGurk (Nature 264, 746-748, 1976) refers to the blending of conflicting audio-visual messages. By taking advantage of this phenomenon the study explored whether visual cues (i.e. manner of articulation) in ipsilesional (right) space would help a patient with auditory neglect to mentally reconstruct syllabic sounds voiced in contralesional (left) space. We examined seven patients with clinically detectable visual neglect following right hemisphere damage. All had signs of auditory neglect as documented by the inferior identification of syllables delivered through a loudspeaker on the left side. In contrast, syllabic sounds delivered contralesionally together with visual stimuli in the ipsilesional space significantly increased identification of "neglected" syllabic sounds. Of the increased responses, 23% were classified as illusory blends, thereby suggesting that manner of articulation provides a valuable clue as to the possible "best fit" for a consonant. The susceptibility to the blend illusion was identical in patients and controls. Results indicate that neglected auditory stimuli are retrieved in patients with right hemisphere lesion by the mechanism of the ventriloquist illusion in the presence of a carefully timed sequence of comparisons of auditory signals in the neglected space with visual signals in the attended space. The possibility that neuronal mechanisms that serve audio-visual merger in spatial localization are also utilized for processing speech distinctions is discussed.

A sound field reproduction method for providing the auditory illusion of a virtual sound source in front of a loudspeaker array is proposed. The Kirchhoff-Helmholtz integral has been popularly used to reproduce the sound field using loudspeaker arrays, and related theories have shown that the internal sound field from virtual sources outside of the array can be reconstructed. Unlike the virtual-source-outside case, however, perfect reproduction of the virtual source inside is physically not possible because of the wavefront converging towards the location of the virtual source. The converging wavefront is one of the artifacts that always arise with artificial rendering, and the reduction of such artifact is seen as a key to reproduce the virtual source inside. For example, in the field of Wave Field Synthesis(WFS), it has been addressed that a focused source inside can be reproduced by combining time-reversal operator with the 2.5D Rayleigh integral equation. In this work, we propose three kinds of integr...

We report that high doses of the benzodiazepine derivative, clotiazepam, given in addition to standard neuroleptics often exert a minor beneficial effect on long-lasting, neuroleptic resistant auditory hallucinations in chronic schizophrenic patients of the residual type.

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 l...

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.

Like our other senses, the auditory system can produce illusions. Prominent among these are distortion products: when listening to two tones, one of frequency f1 and the second of a higher frequency f2, an individual may hear not only these primary tones, but also a difference tone of frequency f2 - f1, a sum tone of frequency f2 + f1, and combination tones of frequencies such as 2f1 - f2 and 2f2 - f1. Discovered by Tartini early in the eighteenth century, these illusory sounds are sufficiently conspicuous that they were employed to carry melodies in classical compositions. Distortion products originate within the cochlea, where they manifest themselves in the basilar membrane's vibration. Here we demonstrate distortion products in individual hair cells of the bullfrog's sacculus, where they emerge from a nonlinearity inherent in the mechanoelectrical transduction process. In addition to offering an explanation for cochlear distortion products, our results suggest that the mechanical properties of hair bundles significantly influence the basilar membrane's motion.

The hypothesis that the extent of spatial separation between successive sound events directly affects the perception of time intervals between these events was tested using an apparent motion paradigm. Subjects listened to four-tone pitch patterns whose individual tones were sounded alternately at one of two loudspeaker positions, and they adjusted the alternation rate until they could no longer distinguish the four-tone ordering of the pattern. Four horizontal and two vertical loudspeaker separations were tested. Results indicate a direct relation between horizontal separation and the critical stimulus onset asynchrony (SOA) between successive tones within a pattern. At the critical SOA, subjects reported hearing not a four-tone pattern, but two pairs of two-note groups overlapping in time. The findings are discussed in the context of auditory spatial processing mechanisms and possible sensory-specific representational constraints.

The scale illusion (Deutsch, 1975) shows the importance of frequency range in the perceptual organization of a sequence of notes. This paper includes three experiments on the scale illusion. Experiments 1 and 2 demonstrated that if the structure of the pattern of notes used in the original scale illusion study is altered slightly, by adding or subtracting a pair of notes from the ends of the sequence, there is a significant decrease in the rate of frequency-based responses, suggesting a weaker illusion. Experiment 3 investigated two features of the note patterns that may have led to this change. Specifically, it asked whether the decrease in the strength of the illusion is due to (1) the nature of the notes at the extremes of the frequency range and/or (2) the nature of the notes at the crossing point of the two scales. While both sources were found to affect the strength of the scale illusion, the former had a greater influence.

A technique of inducing auditory illusions was used so that 192 undergraduates heard through headphones either three asynchronous dichotic versions of the same repeating word, at each of three auditory locations (left, center, and right), or only one single repeating word, monaurally or diotically, at each location. Independent illusory changes at each location were reported. Subjects' reports of lexical illusions, but not nonlexical illusions, were fewer at the right ear for threevs. one-signal listening. These results support the homolog activation hypothesis ( Boles, 1990 ) in which disruption of interhemispheric communication occurs for the hemisphere least capable of processing lexical information. In the current experiment homolog activation led to loss of lexical information when received from auditory positions other than the right, when three signals are presented. Lexical illusions (Verbal Transformations) may be the result of the misapplication of lexical knowledge in an ambiguous situation, listening to a recycling word without stabilizing syntactic or semantic context.

The effects of stimulus duration and spatial separation on the illusion of apparent motion in the auditory modality were examined. Two narrow-band noise sources (40 dB, A-weighted) were presented through speakers separated in space by 2.5°, 5°, or 100, centered about the subject’s midline. The duration of each stimulus was 5, 10, or 50 msec. On each trial, the sound pair was temporally separated by 1 of 10 interstimulus onset intervals (ISOIs): 0, 2, 4, 6, 8, 10, 15, 20, 50, or 70 msec. Five subjects were tested in nine trial blocks; each block represented a particular spatial-separation-duration combination. Within a trial block, each ISOI was presented 30 times each, in random order. Subjects were instructed to listen to the stimulus sequence and classify their perception of the sound into one of five categories: single sound, simultaneous sounds, continuous motion, broken motion, or successive sounds. Each subject was also required to identify the location of the first-occurring stimulus (left or right). The percentage of continuous-motion responses was significantly affected by the ISOI [F(9,36) = 5.67,p < .001], the duration × ISOI interaction [F(18,72) = 3.54,p < .0001], and the separation × duration × ISOI interaction [F(36,144) = 1.51,p < .05]. The results indicate that a minimum duration is required for the perception of auditory apparent motion. Little or no motion was reported at durations of 10 msec or less. At a duration of 50 msec, motion was reported most often for ISOIs of 20–50 msec. The effect of separation appeared to be limited to durations and-ISOIs during which little motion was perceived.

Sixteen infants each at 4, 6, and 8 months of age were tested for reaching to sounding toys in the dark under two auditory illusion conditions: the Haas-effect, which creates the illusion of a single lateralized sound based on an interaural intensity difference (the toy was visible and invisible under some test conditions); and the midline illusion, which creates the illusion of a single sound at midline due to an absence of any interaural time or intensity differences (invisible toy condition only). No-sound control trials indicated the level of spontaneous reaching in the dark. Results indicate that by 4 months infants perceive both the Haas-effect and midline illusions. The ability to reach both for invisible and visible sounding objects in the dark was well developed by 4 months of age, although developmental changes in aspects of reaching behavior were observed and, at all ages, object contact was most frequent when visual localization cues accompanied sound localization cues. The incidence of spontaneous reaching in the dark was low and did not vary with age. Theoretical and methodological implications of this research are discussed.

This study investigated whether the apparent completeness of the acoustic speech signal during phonemic restoration derives from a process of auditory induction (Warren, 1984) or segregation, or whether it is an auditory illusion that accompanies the completion of an abstract phonological representation. Specifically, five experiments tested the prediction of the auditory induction (segregation) hypothesis that active perceptual restoration of an [s] noise that has been replaced with an extraneous noise would use up a portion of that noise's high-frequency energy and consequently change the perceived pitch (timbre, brightness) of the extraneous noise. Listeners were required to compare the pitch of a target noise, which replaced a fricative noise in a sentence, with that of a probe noise preceding or following the speech. In the first two experiments, a significant tendency was found in favor of the auditory induction hypothesis, although the effect was small and may have been caused by variations in acoustic context. In the following three experiments, a larger variety of stimuli were used and context was controlled more carefully; this yielded negative results. Phoneme identification responses collected in the same experiments, as well as informal observations about the quality of the restored phoneme, suggested that restoration of a fricative phone distinct from the extraneous noise did not occur; rather, the spectrum of the extraneous noise itself influenced phoneme identification. These results suggest that the apparent auditory restoration which accompanies phonemic restoration is illusory, and that the schema-guided process of phoneme restoration does not interact with auditory processing.

NEWPORT BEACH, CALIFORNIA-- At the 140th meeting of the Acoustical Society of America here last week, a psychologist demonstrated that an auditory illusion based on the tritone--two notes a half-octave apart played together--is perceived differently by listeners with different linguistic histories. And those perceptions might help psychologists understand how the brain rewires itself during childhood.

Background: The sound-induced flash illusion is an auditory-visual illusion – when a single flash is presented along with two or more beeps, observers report seeing two or more flashes. Previous research has shown that the illusion gradually disappears as the temporal delay between auditory and visual stimuli increases, suggesting that the illusion is consistent with existing temporal rules of neural activation in the superior colliculus to multisensory stimuli. However little is known about the effect of spatial incongruence, and whether the illusion follows the corresponding spatial rule. If the illusion occurs less strongly when auditory and visual stimuli are separated, then integrative processes supporting the illusion must be strongly dependant on spatial congruence. In this case, the illusion would be consistent with both the spatial and temporal rules describing response properties of multisensory neurons in the superior colliculus. Methodology/Principal Findings: The main aim of this study was to investigate the importance of spatial congruence in the flash-beep illusion. Selected combinations of one to four short flashes and zero to four short 3.5 KHz tones were presented. Observers were asked to count the number of flashes they saw. After replication of the basic illusion using centrally-presented stimuli, the auditory and visual components of the illusion stimuli were presented either both 10 degrees to the left or right of fixation (spatially congruent) or on opposite (spatially incongruent) sides, for a total separation of 20 degrees. Conclusions/Significance: The sound-induced flash fission illusion was successfully replicated. However, when the sources of the auditory and visual stimuli were spatially separated, perception of the illusion was unaffected, suggesting that the ‘‘spatial rule’’ does not extend to describing behavioural responses in this illusion. We also find no evidence for an associated ‘‘fusion’’ illusion reportedly occurring when multiple flashes are accompanied by a single beep.

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 gen...

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.

Sensory (perceptual) illusion is said to be ‘promiscuous’ in Nyāya. Promiscuity of awareness here means that it deals with two ‘objects’ at the same time. ‘Illusion’ is used for cases where something is seen but looks to be other than it is or is ‘taken’ to be. The first section of this chapter describes seeing and seeing-as. The second section considers two Buddhist analyses of illusion. The third section explores the Advaita view of the inexplicability of the appearance. The fourth section considers the Prābhākara view of no-illusion. The fifth section expounds the Nyāya analysis of illusion, which is called the ‘misplacement’ theory. The sixth section explains fictions and fantasies. The last section compares sense-datum and direct realism.

When an amplitude-modulated noise generated from a spoken word is presented simultaneously with the word's printed version, the noise sounds more speechlike. This auditory illusion obtained by Frost, Repp, and Katz (1988) suggests that subjects detect correspondences between speech amplitude envelopes and printed stimuli. The present study investigated whether the speech envelope is assembled from the printed word or whether it is lexically addrressed. In two experiments subjects were presented with speech-plus-noise and with noise-only trials, and were required to detect the speech in the noise. The auditory stimuli were accompanied with matching or non-matching Hebrew print, which was unvoweled in Experiment 1 and voweled in Experiment 2. The stimuli of both experiments consisted of high-frequency words, low-frequency words, and non-words. The results demonstrated that matching print caused a strong bias to detect speech in the noise when the stimuli were either high- or low-frequency words, whereas no bias was found for non-words. The bias effect for words or non-words was not affected by spelling to sound regularity; that is, similar effects were obtained in the voweled and the unvoweled conditions. These results suggest that the amplitude envelope of the word is not assembled from the print. Rather, it is addressed directly from the printed word and retrieved from the mental lexicon. Since amplitude envelopes are contingent on detailed phonetic structures, this outcome suggests that representations of words in the mental lexicon are not only phonological but also phonetic in character.

Right auditory cortex dysfunction during musical hallucinations occurred in an 88-year-old woman, who was otherwise cognitively intact. We assessed this phenomenon with a combination of neuromagnetic and cerebral blood-flow measurements.

In a previous study, we exploited the Gestalt principle of closure to create illusory vowel sounds and examined the neural correlates of their perception using fMRI. When two formants of a synthetic vowel are presented in an alternating pattern, filling the gaps in each formant with bursts of noise causes the formants to be heard as continuous and more vowel‐like. When this "Illusion" condition was modified by increasing the formant‐to‐noise ratio (FNR), the formants were heard as interrupted (“Illusion Break” condition) and less vowel‐like. BOLD signal in the Middle Temporal Gyrus (MTG) was greater for Illusion than for Illusion‐Break stimuli, reflecting the difference in speechlikeness. Primary auditory areas (PAC) exhibited the opposite pattern, probably because Illusion‐Break stimuli contain more perceived sound onsets than the Illusion stimuli. In the current study we examine whether the neural activation to illusory vowels and sound onsets is modulated by attention. Participants were scanned while l...

Holophony is in acoustics what holography is in optics. Just as might claim to be the ideal optical illusion, so might claim to be the perfect auditory illusion. As illustration of general principles theoretical basis was obtained by the Bourbakt group, and otherwise by Gabor theory. It is shown that using limited number of secondary Huygens sources one can provide a very presentable auditory illusion imaging the primary sound source.

Children spend a vast majority of time in reverberant environments. However, their auditory system appears not to be as fully equipped as that of adults for coping with reverberation. In our studies we simulate simple aspects of reverberation by exploiting a well‐known auditory illusion known as the precedence effect (PE). Stimuli consist of clicks or speech, pairs of source (lead), and its first‐arriving reflection (lag). Results from typically developing normal‐hearing children ages 3–10 suggest that the PE undergoes significant maturation during childhood. In addition, we studied 10‐year‐old children with specific language impairment (SLI), who are delayed on expressive and receptive language. Performance was similar to that of younger, language‐age‐matched children, suggesting that the PE could be a useful clinical tool for measuring nonverbal temporal information processing. The PE was also used to study deaf adults with bilateral cochlear implants. Results suggest that binaural sensitivity is only available when the cochlea can be directly stimulated, but in free field the temporal smearing caused by the microphone leads to degraded and abnormal PE. Taken together, these studies suggest that a basic and necessary auditory function, that of suppressing echoes, fails under numerous circumstances, in children and in deaf, bilateral cochlear implant users.

Sound is arguably the most widely perceived and pervasive form of energy in our world, and among the least understood, in part due to the complexity of its underlying principles. A series of interactive displays has been developed which demonstrates that the nature of sound involves the propagation of energy through space, and illustrates the definition of psychoacoustics, which is how listeners map the physical aspects of sound and vibration onto their brains. These displays use auditory illusions and commonly experienced music and sound in novel presentations (using interactive computer algorithms) to show that what you hear is not always what you get. The areas covered in these demonstrations range from simple and complex auditory localization, which illustrate why humans are bad at echolocation but excellent at determining the contents of auditory space, to auditory illusions that manipulate fine phase information and make the listener think their head is changing size. Another demonstration shows how auditory and visual localization coincide and sound can be used to change visual tracking. These demonstrations are designed to run on a wide variety of student accessible platforms including web pages, stand‐alone presentations, or even hardware‐based systems for museum displays.

Background Two forms of familial temporal lobe epilepsy (FTLE) have been described: mesial FTLE and FTLE with auditory auras. The gene responsible for mesial FTLE has not been mapped yet, whereas mutations in theLGI1(leucine-rich, glioma-inactivated 1) gene, localized on chromosome 10q, have been found in FTLE with auditory auras. Objective To describe magnetic resonance imaging (MRI) findings in patients with FTLE with auditory auras. Design and Methods We performed detailed clinical and molecular studies as well as MRI evaluation (including volumetry) in all available individuals from one family, segregating FTLE from auditory auras. Results We evaluated 18 of 23 possibly affected individuals, and 13 patients reported auditory auras. In one patient, auditory auras were associated with deja vu; in one patient, with ictal aphasia; and in 2 patients, with visual misperception. Most patients were not taking medication at the time, although all of them reported sporadic auras. Two-point lod scores were positive for 7 genotyped markers on chromosome 10q, and a Zmax of 6.35 was achieved with marker D10S185 at a recombination fraction of 0.0. Nucleotide sequence analysis of theLGI1gene showed a point mutation, IVS7-2A>G, in all affected individuals. Magnetic resonance imaging was performed in 22 individuals (7 asymptomatic, 4 of them carriers of the affected haplotype on chromosome 10q and the IVS7-2A>G mutation). Lateral temporal lobe malformations were identified by visual analysis in 10 individuals, 2 of them with global enlargement demonstrated by volumetry. Mildly reduced hippocampi were observed in 4 individuals. Conclusions In this family with FTLE with auditory auras, we found developmental abnormalities in the lateral cortex of the temporal lobes in 53% of the affected individuals. In contrast with mesial FTLE, none of the affected individuals had MRI evidence of hippocampal sclerosis.

The cocktail‐party paradigm was applied to nonspeech signals. Pure‐tone stimuli were used in an extension of the Franssen effect, an auditory illusion wherein the location of a slow‐onset signal is perceived to be the same as a simultaneous, contralateral sudden‐onset signal. Listeners heard simultaneous sudden‐onset (transient) and contralateral slow‐onset (steady‐state) tones in a reverberant environment with a second delayed transient from a third azimuthal location. Results showed that the Franssen effect was either maintained or ‘‘reset,’’ but not reduced. The ongoing steady‐state tone was perceived either at the initial‐transient and then delayed‐transient location, or at the initial transient location only. None of the listeners showed a location bias to the delayed transient tone when its frequency differed from the initial signal frequency or was replaced with noise. In additional conditions based on the ‘‘false Haas effect,’’ consonant–vowel pairs representing transient and steady‐state signals ...

In recent years, cognitive neuroscience has been making great efforts to home in on the difference between the physical stimulus and the perceived sensation, hence the attempts to find neural correlates of what we actually perceive. In auditory illusions, the pitch of a sound – its subjective highness or lowness – may not be the same as its physical frequency. In the missing frequency (MF) illusion, for example, people can hear frequencies not present in physical sound waves. Using MF stimuli and magnetoencephalography (MEG), Patel and Balaban recently showed that there is a correlation between the temporal pattern of brain activation in the right cerebral hemisphere and the subjectively perceived pitch [Nature Neurosci. (2001) 4, 839–844]. Using the fact that people differ in their susceptibility to the MF illusion, Patel and Balaban divided their subjects into those who perceived pitch change in the same direction as frequency change, and those who perceived it in the opposite direction. Comparing MEG scans from the two groups of subjects, they found that, although many areas of the brain respond to the stimulus of a frequency change, only areas in the right hemisphere code for change of subjective pitch. MW

In a classic study, Warren (1971) replaced the medial /s/ in legislatures with a cough, and found that adult listeners heard the word as being complete. This auditory illusion demonstrates effects of both bottom‐up and top‐down information: it occurs only when there is a possible masking noise (it does not occur if the /s/ is replaced with silence), and it occurs at least in part because of the listener’s knowledge that legislatures is a real word. Thus, it involves an interaction between multiple sources of information. The present study investigates whether infants will also show such an effect, and thus whether this interaction between levels of language processing is itself something which develops over time. Infants are shown videos of a cat and a dog in a preferential‐looking paradigm, and hear the words kitty and doggie both in the clear, and with the medial stop consonant replaced by either noise or silence. Results examine whether infants will treat the words as whole (that is, match them to the appropriate referent) when the middle sound is replaced with noise as compared to when it is replaced with silence. [Work supported by NIH Grant R03 HD37822‐01 to the University of Iowa.]