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PubMed1992

Perceptual asymmetry in psychosis-prone college students: evidence for left-hemisphere overactivation.

The hypothesis that psychosis-prone students demonstrate a pattern of exaggerated perceptual asymmetry across both left- and right-hemisphere dichotic-listening tasks (consonant-vowel [CV] and tonal contour discrimination) was investigated. Subjects who scored high on the Perceptual Aberration or Magical Ideation scale or both (n = 20) demonstrated a significantly exaggerated right-ear advantage on a CV task in relation to normal control subjects (n = 27) but showed a reduced left-ear advantage on a tone task. The hypothesis of exaggerated functional lateralization across hemispheres in the psychosis-prone subjects was not supported, but the results are consistent with a hypothesis of left hemisphere overactivation in this sample.

Adult↗
PubMed2001

Individual differences in the processing of speech and nonspeech sounds by normal-hearing listeners.

While a large portion of the variance among listeners in speech recognition is associated with the audibility of components of the speech waveform, it is not possible to predict individual differences in the accuracy of speech processing strictly from the audiogram. This has suggested that some of the variance may be associated with individual differences in spectral or temporal resolving power, or acuity. Psychoacoustic measures of spectral-temporal acuity with nonspeech stimuli have been shown, however, to correlate only weakly (or not at all) with speech processing. In a replication and extension of an earlier study [Watson et al., J. Acoust. Soc. Am. Suppl. 1 71. S73 (1982)] 93 normal-hearing college students were tested on speech perception tasks (nonsense syllables, words, and sentences in a noise background) and on six spectral-temporal discrimination tasks using simple and complex nonspeech sounds. Factor analysis showed that the abilities that explain performance on the nonspeech tasks are quite distinct from those that account for performance on the speech tasks. Performance was significantly correlated among speech tasks and among nonspeech tasks. Either, (a) auditory spectral-temporal acuity for nonspeech sounds is orthogonal to speech processing abilities, or (b) the appropriate tasks or types of nonspeech stimuli that challenge the abilities required for speech recognition have yet to be identified.

Adolescent↗
PubMed1993

Boundaries of separability between melody and rhythm in music discrimination: a neuropsychological perspective.

The detailed study of a patient who suffered from a severe amelodia without arhythmia as a consequence of bilateral temporal lobe damage revealed that the processing of melodic information is at least partially separable from the processing of rhythmic information. This dissociation was replicated across different sets of material, was supported by the presence of a reversed association, and was maintained in conditions that promote integration in the normal brain. These results argue against the view that melody and rhythm are treated as a unified dimension throughout processing. At the same time, they support the view that integration takes place after early separation of the two dimensions.

Adult↗
PubMed1984

Ontogenesis of learning: III. Variation in the rat's differential reflexive and learned responses to sound frequencies.

The ontogenesis of the rat's differential response to variation in sound frequency was investigated. Two behavioral procedures were employed: (a) a differential Pavlovian conditioning procedure that provided a means of inferring the pup's capacity to learn to respond differentially on the basis of sound frequency (e.g., 2000 Hz vs 900 Hz), and (b) a habituation-generalization task that indexed the capacity to discriminate different sound frequencies from the pup's reflexive behavior. Pups less than 17 days old failed to learn to respond differentially to a 2000-Hz vs 900-Hz tone (Experiment I, IIA, IIB, and III). In contrast, pups only 14 days old discriminated tones that differed by as little as 200 Hz when the reflex-habituation-generalization procedure was employed (Experiment IV). This suggests that the reflexive and learned behaviors, potentially controlled by sound frequency, are dissociated during ontogenesis, the former emerging prior to the latter. These data were interpreted within a neurobiological framework that related ontogenetic changes in behavioral capacity to a caudal-to-rostral maturational sequence in the ascending auditory system of the components that contribute to these capacities.

Acoustic Stimulation↗
PubMedDate not supplied

Auditory memory and age-related differences in two-tone frequency discrimination: trace decay and interference.

We investigated age-related differences in the time course of two-tone frequency discrimination. Healthy young and elderly adults with normal hearing acuity in the 500-2000 Hz range performed a two-alternative forced choice frequency discrimination task. The stimuli were short tones separated by either a 250-ms (short), 850-ms (medium), or 3000-ms (long) silent inter-interstimulus interval (ISI). Frequency discrimination thresholds were estimated using an adaptive staircase procedure. Although young listeners performed better than the elderly at all ISIs, the latter showed a dramatic elevation of discrimination thresholds at 250 ms, while the thresholds of the young subjects increased significantly at 3000 ms. These results suggest that the elderly may be especially vulnerable to the effects of masking produced by the second tone at the short interval, whereas the young listeners tend to be differentially affected by the trace decay at long ISI. The results are discussed in the framework of stimulus persistence hypothesis.

Acoustic Stimulation↗
PubMedDate not supplied

Behavioral auditory function after transection of crossed olivo-cochlear bundle in the cat. V. Pure-tone intensity discrimination.

This report describes the cat's ability to discriminate pure-tone intensity differences after transection of the crossed olivo-cochlear bundle at the floor of the fourth ventricle. Cats were trained by behavioral (avoidance) conditioning to detect intensity difference above 75 dB re 0.0002 dyne/cm2 of 10 000 Hz tones, using the repetitive method. Postoperative comparison of data from 5 experimental animals and 5 sham-operated control animals showed minimal differences which reflects merely functional biological variance. Neurohistological examination confirmed the accuracy of the lesion placement.

Acoustic Stimulation↗
PubMed2005

A kind of auditory 'primitive intelligence' already present at birth.

'Primitive intelligence' in audition refers to the capacity of the auditory system to adaptatively model the acoustic regularity and react neurophysiologically to violations of such regularity, thus supporting the ability to predict future auditory events. In the present study, event-related brain potentials to pairs of tones were recorded in 11 human newborns to determine the infants' ability to extract an abstract acoustic rule, the direction of a frequency change. Most of the pairs (standard, P = 0.875) were of ascending frequency (i.e. the second tone higher than the first), while the remaining pairs (deviant, P = 0.125) were of descending frequency (the second tone being lower). Their frequencies varied among seven levels to prevent discrimination between standard and deviant pairs on the basis of absolute frequencies. We found that event-related brain potentials to deviant pairs differed in amplitude from those to standard pairs at 50-450 ms from the onset of the second tone of a pair, indicating the infants' ability to represent the abstract rule. This finding suggests the early ontogenetic origin of 'primitive intelligence' in audition that eventually may form a prerequisite for later language acquisition.

Acoustic Stimulation↗
PubMed1988

Spectro-temporal analysis in normal-hearing and cochlear-impaired listeners.

Detection thresholds for a 1.0-kHz pure tone were determined in unmodulated noise and in noise modulated by a 15-Hz square wave. Comodulation masking release (CMR) was calculated as the difference in threshold between the modulated and unmodulated conditions. The noise bandwidth varied between 100 and 1000 Hz. Frequency selectivity was also examined using an abbreviated notched-noise masking method. The subjects in the main experiment consisted of 12 normal-hearing and 12 hearing-impaired subjects with hearing loss of cochlear origin. The most discriminating conditions were repeated on 16 additional hearing-impaired subjects. The CMR of the hearing-impaired group was reduced for the 1000-Hz noise bandwidth. The reduced CMR at this bandwidth correlated significantly with reduced frequency selectivity, consistent with the hypothesis that the across-frequency difference cue used in CMR is diminished by poor frequency selectivity. The results indicated that good frequency selectivity is a prerequisite, but not a guarantee, of large CMR.

Adult↗
PubMed1992

Spectral pattern discrimination by children.

This research measured the ability of 47 children, aged 4-9 years, to use spectral shape cues to discriminate among random-intensity sounds. The children were tested in forced-choice paradigms that were embedded in a video game format. Two classes of sounds were studied: tonal complexes with sinusoidally rippled amplitude spectra, and synthetic speech sounds (isolated vowels and consonants). The discriminability of the sounds was measured both in quiet and in a background of wide-band noise. Although the intersubject variability in performance was high, especially among the youngest children, the results revealed a substantial age effect. For both classes of sounds, the performance of the younger children was significantly poorer than the performance of an adult control group. However, there was no evidence in the data that the masking effect of the noise was greater for the children than for the adults.

Adolescent↗
PubMed2000

Specificity of perceptual learning in a frequency discrimination task.

On a variety of visual tasks, improvement in perceptual discrimination with practice (perceptual learning) has been found to be specific to features of the training stimulus, including retinal location. This specificity has been interpreted as evidence that the learning reflects changes in neuronal tuning at relatively early processing stages. The aim of the present study was to examine the frequency specificity of human auditory perceptual learning in a frequency discrimination task. Difference limens for frequency (DLFs) were determined at 5 and 8 kHz, using a three-alternative forced choice method, for two groups of eight subjects before and after extensive training at one or the other frequency. Both groups showed substantial improvement at the training frequency, and much of this improvement generalized to the nontrained frequency. However, a small but statistically significant component of the improvement was specific to the training frequency. Whether this specificity reflects changes in neural frequency tuning or attentional changes remains unclear.

Adolescent↗
PubMed2000

Fidelity of three-dimensional-sound reproduction using a virtual auditory display.

The fidelity of reproducing free-field sounds using a virtual auditory display was investigated in two experiments. In the first experiment, listeners directly compared stimuli from an actual loudspeaker in the free field with those from small headphones placed in front of the ears. Headphone stimuli were filtered using head-related transfer functions (HRTFs), recorded while listeners were wearing the headphones, in order to reproduce the pressure signatures of the free-field sounds at the eardrum. Discriminability was investigated for six sound-source positions using broadband noise as a stimulus. The results show that the acoustic percepts of real and virtual sounds were identical. In the second experiment, discrimination between virtual sounds generated with measured and interpolated HRTFs was investigated. Interpolation was performed using HRTFs measured for loudspeaker positions with different spatial resolutions. Broadband noise bursts with flat and scrambled spectra were used as stimuli. The results indicate that, for a spatial resolution of about 6 degrees, the interpolation does not introduce audible cues. For resolutions of 20 degrees or more, the interpolation introduces audible cues related to timbre and position. For intermediate resolutions (10 degrees - 15 degrees) the data suggest that only timbre cues were used.

Acoustic Stimulation↗
PubMed1988

Discrimination of interaural differences of time in the envelopes of high-frequency signals: integration times.

Listeners detected interaural differences of time in trains of high-frequency clicks. The manipulated variables were the number of clicks in the train and the period between clicks. Thresholds were compared to an optimal integrator, where the binaural information accrued from each click in the stimulus train is equivalent. In agreement with data reported in the past, integration is optimal only when the period between clicks exceeds approximately 10 ms and when the duration of the entire stimulus train is less than about 250 ms. The first constraint represents a limitation due to a form of "binaural adaptation" and the second is due to a limited "integration period."

Attention↗
PubMed2004

Receptive amusia: temporal auditory processing deficit in a professional musician following a left temporo-parietal lesion.

This study examined the musical processing in a professional musician who suffered from amusia after a left temporo-parietal stroke. The patient showed preserved metric judgement and normal performance in all aspects of melodic processing. By contrast, he lost the ability to discriminate or reproduce rhythms. Arrhythmia was only observed in the auditory modality: discrimination of auditorily presented rhythms was severely impaired, whereas performance was normal in the visual modality. Moreover, a length effect was observed in discrimination of rhythm, while this was not the case for melody discrimination. The arrhythmia could not be explained by low-level auditory processing impairments such as interval and length discrimination and the impairment was limited to auditory input, since the patient produced correct rhythmic patterns from a musical score. Since rhythm processing was selectively disturbed in the auditory modality, the arrhythmia cannot be attributed to a impairment of supra-modal temporal processing. Rather, our findings suggest modality-specific encoding of musical temporal information. Besides, it is proposed that the processing of auditory rhythmic sequences involves a specific left hemispheric temporal buffer.

Acoustic Stimulation↗
PubMedDate not supplied

Presbyacusis, hearing aids and aging.

This paper considers the factors of presbyacusis and age-related psychological changes in older adults in terms of their effects on the use or potential use of hearing aids as a means of improving aural communication. Data are presented on the prevalence of hearing impairment and the extent of hearing aid use in aging listeners. Four major classes of presbyacusis are described (sensory, neural, metabolic, and cochlear conduvtive) and a hearing aid prognosis is made for each type of disorder. It is shown that aging produces deficits in pure-tone thresholds, the speech reception threshold, and speech discrimination, but not all losses can be 'corrected' with a hearing aid. Binaural (stereophonic) devices are psychoacoustically superior to monaural devices; however, behavioral and personality changes in older patients often create problems of adaptation to the binaural aid. These changes may also affect the fitting of an aid and the patient's ability to learn to use it. Some practical suggestions are offered on the evaluation of hearing aids and it is emphasized that adequate orientation and counseling are typically required if hearing aid treatment is to be successful in presbyacusis.

Adaptation, Psychological↗
PubMed1993

Receptive field plasticity in the auditory cortex during frequency discrimination training: selective retuning independent of task difficulty.

Classical conditioning is known to induce frequency-specific receptive field (RF) plasticity in the auditory cortex (ACx). This study determined the effects of discrimination training on RFs at two levels of task difficulty. Single unit and cluster discharges were recorded in the ACx of adult guinea pigs trained in a tone-shock frequency discrimination paradigm (30 intermixed trials each of positive conditioned stimulus [CS+]-shock and negative CS [CS-] alone) with behavioral performance indexed by the cardiac deceleration conditioned response (CR). After training in an easy task in which subjects developed discriminative CRs, they were trained in a difficult task (reduced frequency distance between CS+ and CS-) in which they failed to discriminate. However, frequency-specific RF plasticity developed at both levels of task difficulty. Responses to the frequency of the CS+ were increased, whereas responses to other frequencies, including the CS- and the prepotent best frequency (BF) were reduced. In many cases, tuning was shifted such that the frequency of the CS+ became the new BF. The effects were present or stronger after a 1-hr retention interval. The role of RF plasticity in the ACx is discussed for behavioral performance and information storage.

Animals↗
PubMed2004

Effects of discrimination task difficulty on N1 and P2 components of late auditory evoked potential.

The present study investigated the question of whether, in healthy young listeners, increases in discrimination task difficulty will alter the amplitude of either the N1 or P2 components of the late auditory evoked potential (LAEP). Using a stimulus oddball procedure, listeners discriminated changes in the frequency of ongoing tonal stimuli. On different test runs, task difficulty was manipulated by decreasing the size of the frequency differences and/or adding competing speech babble to the nontest ear. Both stimulus procedures produced significant decreases in P2 amplitude but had no effects on N1 amplitudes. This finding of selective effects on later rather than earlier occurring components of the LAEP provides objective evidence that some forms of auditory processing are mediated at more central levels of the system.

Acoustic Impedance Tests↗
PubMed1982

An operant tracking procedure in the auditory assessment of profoundly retarded individuals.

The present study investigated a discrete-trials, operant tracking and a descending-series procedure for the determination of hearing levels with profoundly retarded individuals. These individuals were previously diagnosed as untestable. Following stimulus-control training with errorless discrimination procedures, hearing levels for each individual were examined with both procedures. For P-1 and P-2, the operant tracking procedure was administered following a descending-series procedure. Both were observed to "track" their own hearing levels. For P-3, the operant tracking procedure was administered first, followed by the descending-series procedure. Although P-3 also "tracked" her own hearing level, more variable responding was observed. Nonetheless, the operant tracking procedure proved quite workable and may provide for improved hearing testing with "difficult-to-test" individuals.

Adolescent↗
PubMed1982

Octave discrimination: an experimental confirmation of the "stretched" subjective octave.

Discrimination of the musical octave was measured by the method of constant stimuli with roving standards and four response categories. For each of three musically trained listeners, and two of three untrained listeners, the estimated value of the subjective octave was "stretched" slightly sharper than the physical octave of 1200 cents. The magnitude of this stretch, about 20 cents on the average, replicated earlier findings obtained by the method of adjustment. A Thurstonian decision-theory model, providing iterative parametric solutions, generated an excellent fit to listeners' psychophysical functions. The present experimental task is best described by a noncategorical model of interval perception.

Adult↗