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A S Bregman

Publications and source records attributed to A S Bregman.

At least 19 recordsLinked to original sources
PubMed1992

The phonetic integration of speech and non-speech sounds: effects of perceived location.

The third-formant (F3) transition of a three-formant /da/ or /ga/ syllable was extracted and replaced by sine-wave transitions that followed the F3 centre frequency. The syllable without the F3 transition (base) was always presented at the left ear, and a /da/ (falling) or /ga/ (rising) sine-wave transition could be presented at either the left, the right, or both ears. The listeners perceived the base as a syllable, and the sine-wave transition as a non-speech whistle, which was lateralized near the left ear, the right ear, or the middle of the head, respectively. In Experiment 1, the sine-wave transition strongly influenced the identity of the syllable only when it was lateralized at the same ear as the base (left ear). Phonetic integration between the base and the transitions became weak, but was not completely eliminated, when the latter was perceived near the middle of the head or at the opposite ear as the base (right ear). The second experiment replicated these findings by using duplex stimuli in which the level of the sine-wave transitions was such that the subjects could not reliably tell whether a /da/ or a /ga/ transition was present at the same ear as the base. This condition was introduced in order to control for the possibility that the subjects could have identified the syallables by associating a rising or falling transition presented at the left ear with a /da/ or /ga/ percept. Alternative suggestions about the relation between speech and non-speech perceptual processes are discussed on the basis of these results.

Acoustic Stimulation↗
PubMed1990

Auditory grouping based on fundamental frequency and formant peak frequency.

The perceptual grouping of a four-tone cycle was studied as a function of differences in fundamental frequencies and the frequencies of spectral peaks. Each tone had a single formant and at least 13 harmonics. In Experiment 1 the formant was created by filtering a flat spectrum and in Experiment 2 by adding harmonics. Fundamental frequency was found to be capable of controlling grouping even when the spectra spanned exactly the same frequency range. Formant peak separation became more effective as the sharpness (amplitude of the peak relative to a spectral pedestal) increased. The effect of each type of acoustic difference depended on the task. Listeners could group the tones by either sort of difference but were also capable of resisting the disruptive effect of the other one. This was taken as evidence for the presence of a schema-based process of perceptual grouping and the relative weakness of primitive segregation.

Adult↗
PubMed1990

Auditory streaming and the continuity illusion.

In the present experiment, auditory stream organization was investigated in the presence of perceptually restored continuity. It was found that auditory streaming processes tend to yield the same perceptual organization independently of the presence or absence of perceptual restoration. Other observations include the dominance of frequency proximity over trajectory as a perceptual organization principle, and the effect of harmonic enrichment on perceptual grouping.

Adult↗
PubMed1990

Fusion of auditory components: effects of the frequency of amplitude modulation.

The fusion of two amplitude-modulated (AM) tones presented simultaneously was studied. Subjects were presented with an AM tone (A) followed by a copy of itself (B) which was accompanied by another AM tone (C). In different experiments, the subjects were asked either to rate how clearly they could hear Tone B in the BC mixture or whether Tone B was present or not. The stronger the fusion of Tones B and C, the harder it was to "hear out" Tone B. It was found that fusion was strongest when Tones B and C were modulated at the same rate; segregation curves were obtained for the degree of mismatch of modulation frequency.

Adult↗
PubMed1989

Role of predictability of sequence in auditory stream segregation.

This study evaluates the role of item predictability in auditory temporal coherence. Thirteen normal-hearing subjects were required to hold together long tonal sequences as single strings of notes. Temporal and spectral predictability of successive notes in a sequence varied as a function of experimental condition. As the frequency separation of the notes in the sequence increased, the subjects found it more difficult to hold the sequence together as a single stream. There was no significant difference in subjects' abilities in performing this task as a function of experimental condition. That is, the predictability of successive notes appeared not to have a role in temporal coherence.

Attention↗
PubMed1989

The effects of auditory streaming on duplex perception.

When a formant transition and the remainder of a syllable are presented to subjects' opposite ears, most subjects perceive two simultaneous sounds: a syllable and a nonspeech chirp. It has been demonstrated that, when the remainder of the syllable (base) is kept unchanged, the identity of the perceived syllable will depend on the kind of transition presented at the opposite ear. This phenomenon, called duplex perception, has been interpreted as the result of the independent operation of two perceptual systems or modes, the phonetic and the auditory mode. In the present experiments, listeners were required to identify and discriminate such duplex syllables. In some conditions, the isolated transition was embedded in a temporal sequence of capturing transitions sent to the same ear. This streaming procedure significantly weakened the contribution of the transition to the perceived phonetic identity of the syllable. It is likely that the sequential integration of the isolated transition into a sequence of capturing transitions affected its fusion with the contralateral base. This finding contrasts with the idea that the auditory and phonetic processes are operating independently of each other. The capturing effect seems to be more consistent with the hypothesis that duplex perception occurs in the presence of conflicting cues for the segregation and the integration of the isolated transition with the base.

Attention↗
PubMed1989

The perceptual segregation of simultaneous auditory signals: pulse train segregation and vowel segregation.

In the experiments reported here, we attempted to find out more about how the auditory system is able to separate two simultaneous harmonic sounds. Previous research (Halikia & Bregman, 1984a, 1984b; Scheffers, 1983a) had indicated that a difference in fundamental frequency (F0) between two simultaneous vowel sounds improves their separate identification. In the present experiments, we looked at the effect of F0s that changed as a function of time. In Experiment 1, pairs of unfiltered or filtered pulse trains were used. Some were steady-state, and others had gliding F0s; different F0 separations were also used. The subjects had to indicate whether they had heard one or two sounds. The results showed that increased F0 differences and gliding F0s facilitated the perceptual separation of simultaneous sounds. In Experiments 2 and 3, simultaneous synthesized vowels were used on frequency contours that were steady-state, gliding in parallel (parallel glides), or gliding in opposite directions (crossing glides). The results showed that crossing glides led to significantly better vowel identification than did steady-state F0s. Also, in certain cases, crossing glides were more effective than parallel glides. The superior effect of the crossing glides could be due to the common frequency modulation of the harmonics within each component of the vowel pair and the consequent decorrelation of the harmonics between the two simultaneous vowels.

Attention↗
PubMed1985

Speech processing ability in alcoholics: a transient impairment and its relation to field dependence.

Alcoholic and non-alcoholic subjects received a test of the ability to identify speech presented against competing speech (Synthetic Sentence Identification) and a test of field dependence (Embedded-Figures Test (EFT). Performance on the speech task (which involved auditory figure-ground differentiation) bore no special relationship to performance on the field-dependence test. However, cross-sectional and longitudinal data suggested that recently-drinking alcoholics are temporarily impaired in their speech-processing ability, recovering this ability after several months of alcohol-abstinence. A relationship between chronicity of alcoholism and field dependence was also observed. The latter relationship, along with findings on auditory tests, were discussed in terms of their relevance to the issue of whether field dependence is an antecedent to or a consequence of alcoholism.

Adult↗
PubMed1978

Auditory streaming is cumulative.

The auditory system appears to begin listening to an input with a basis toward hearing the input as a single stream, but it gradually accumulates evidence over a period of seconds which may lead to the input's being split into substreams. Several seconds of silence or of unpatterned noise slowly remove the bias of the mechanism in favor of these streams. The effects were demonstrated in experiments in which young adult listeners sped up sequences of tones until they split. The sequences varied in the number of tones packaged between recurrent "separators" (periods of silence or of white noise) and in the lengths of these separators.

Acoustic Stimulation↗
PubMed1976

Stream segregation and the illusion of overlap.

When two different sounds continuously alternate at high speed, they segregate into two perceptual streams. The present article shows that this segregation produces a loss of information regarding the sequential relations of the sounds so that they seem perceptually to be overlapped in time. The segregation (and its contribution to perceived overlap) is shown to increase with the perceptual difference between the sounds. The mapping from perceptual difference to perceived overlap is not simple, however, since perceived overlap can also be affected by "perceived auditory continuity," another perceptual effect that responds differently to the perceptual difference between the two sounds.

Acoustic Stimulation↗