SEARCH · Search PubMed
Results for “Pitch Discrimination”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Psychopathy and dual-task performance under focusing conditions.
Thirty psychopathic and 30 nonpsychopathic right-handed White male inmates (selected through R.D. Hare's, 1985b, Psychopathy Checklist) completed concurrent visual and auditory tasks under conditions focusing attention on the visual (i.e., primary) task. Performance indices tested 3 related hypotheses for cognitive deficits in psychopathic individuals: reduced attention to secondary tasks because of excess attention to immediate goals (interference), deficient shifts of attention, and reduced breadth of attention. The absence of differences in primary and secondary task accuracy contradicts the interference hypothesis. However, a trend toward deficits for psychopathic individuals responding with the right hand to primary task targets appearing after other targets, suggests poorer shifting of attention when left-hemisphere resources are engaged. Psychopathic individuals also overresponded to distractors following targets suggesting reduced attention to a peripheral dimension of two-dimensional stimuli.
Hippocampectomy disrupts the topography of conditioned nictitating membrane responses during reversal learning.
The effects of bilateral hippocampectomy on the topography, or shape, of conditioned nictitating membrane (NM) responses were examined during four learning tasks: one-tone delay conditioning, unpaired extinction, two-tone discrimination, and reversal of two-tone discrimination. Results showed that hippocampal ablation altered conditioned NM response topography only during reversal learning and not during the other training paradigms. In addition, the shapes of learning curves for hippocampectomized animals were different from those of control animals during reversal conditioning but not during the other paradigms. The implications of these findings with respect to unit-recording studies of hippocampal cellular activity during classical conditioning of the NM response are discussed.
Multidimensional scaling of synthetic musical timbre: perception of spectral and temporal characteristics.
The perceptual correlates of acoustic parameters involved in musical timbre were investigated by examining judgements of timbre dissimilarity. Nine synthetic sounds were created, derived from crossing three levels of spectral and temporal parameters (number of harmonics and rise time, respectively). Two separate conditions were tested, one using single tones, the other using short melodies. Fifteen musically untrained subjects were presented with pairs of stimuli and asked to judge dissimilarity on an 8-point scale. The spatial configuration resulting from multidimensional analysis of the data was best fit by a three-dimensional model, with the first two dimensions accounting for most of the variance. The perceptual space derived from the analysis indicates that these two orthogonal dimensions corresponded closely to the spectral and temporal differences inherent to the stimuli. Similar results were obtained with both melodies and single tones. A second experiment replicated the findings despite the introduction of random loudness variation, indicating that timbre judgements can be made independently of loudness. We conclude that even musically unselected subjects are sensitive to spectral and temporal information in musical tones, and are able to use them independently in making perceptual judgements of musical timbre.
Speech perception under conditions of spectral transformation. I. Phonetic characteristics.
Explore the source record for details and available documents.
"Stimulus generalization" between differentiated visual, auditory, and central stimuli.
Cats were trained to discriminate between two different repetition rates of flicker and of click. Both approach-approach and avoidance-avoidance discriminations were used. After substantial overtraining, transfer of frequency discrimination was initiated to stimulation of the reticular formation using bursts of electrical pulses at the same two repetition rates. Significant levels of discriminated performance were obtained in all cats very quickly, indicating good cross-modal transfer between the peripheral discriminanda and the central stimuli. The literature on stimulus generalization and cross-modal transfer is reviewed and the findings of this experiment are discussed in that context. Certain conditions are defined which, if satisfied, justify the interpretation that stimulus generalization or rapid cross-modal transfer indicate that facilitation of subsequent tasks in a training sequence can be attributed to mediation by a specific neuronal mechanism established by training on a previous task. The present experiment was designed in view of such criteria. The evidence of good cross-modal transfer is interpreted to mean that brain mechanisms storing memories about discriminations between visual or auditory stimuli with different repetition rates can be effectively activated by gross electrical stimuli at the same repetition rates. Conflict trials were then carried out in which flicker or click at either frequency was contradicted by concurrent RF stimuli at the other frequency. As the current level of RF stimuli was parametrically increased, it was found that the central stimuli achieved almost complete control over the behavioral outcome in most cases. Concurrent transfer of training, using a counterbalanced training sequence, was then carried out to stimulation of the visual cortex, lateral geniculate, medial geniculate, and the intralaminar nuclei of the thalamus. In each case, rapid transfer was displayed by at least one animal. Once performance to brain stimulation at a given repition rate was established, little change was observed when the fine structure of the stimulus was altered by changing parameters of the stimulus burst. These findings are interpreted as providing support for a statistical theory of memory, since they constitute evidence that previously learned discriminative behavior can readily be elicited by compelling large ensembles of neurons in various brain regions to discharge with particular temporal patterns. It is difficult to reconcile these results with theories which postulate that learning establishes new synaptic pathways in which discharge must occur for memories to be retrieved.
[Role of the auditory cortex in the formation of complex reflexes to amplitude-modulated stimuli in rats].
Motor alimentary conditioned reflexes to acoustic stimuli were elaborated in 27 laboratory rats. After bilateral ablation of the auditory cortex, differentiation of tonal stimuli from amplitude-modulated (AM) signals with a 5 c/s modulation frequency was completely abolished, without its subsequent restoration in six months after the operation. Differentiation of tonal from AM-stimuli with a 50 and 500 c/s modulation frequency, however, not only persists, but is elaborated in animals with a preliminarily ablated auditory cortex. Results of the investigation permit to draw the conclusion that the auditory cortex is the centre where the coding of stimuli with a low frequency of amplitude modulation is completed. Correspondingly, the structural organization of the sensory part of the arc of conditioned responses to different classes of AM-stimuli is discussed.
Intensity discrimination of pulsed sinusoids: the effects of filtered noise.
Explore the source record for details and available documents.
Ear dominance of dichotic chords and ear superiority in frequency discrimination.
Explore the source record for details and available documents.
[Experimental contribution to vowel discrimination in frequency transposition of the formants].
Explore the source record for details and available documents.
[Introduction to the concept the threshold of discrimination of timbre. Preliminary note].
Explore the source record for details and available documents.
[Value of in situ measurement for evaluating effective hearing aid amplification at high sound pressure levels].
A careful hearing aid fitting requires consideration of various characteristics of inner ear pathology. The recruitment phenomenon restricts the dynamic range of the impaired hearing and this increase the demands on the hearing aids for a satisfactory correction of the frequency characteristics as well as for an intensity reduction at higher sound pressure level SPL. For years data from coupler or KEMAR (Knowles Electronics Manikin of Acoustical Research) have served to estimate the real ear gain of a hearing aid at higher input levels. In previous papers we reported on some of the differences between coupler measurement and probe tube measurement. The object of this study was to investigate the differences between these two methods at higher input SPL. Therefore, we measured the real ear insertion gain as well as the output characteristics with a 2 cm3 coupler in 80 patients at input levels of 60 dB, 80 dB and 100 dB. The results show differences between the two methods up to 30 dB in both directions in the single patient. Furthermore, the highest compression rate was found in the middle and high frequency range which are crucial for speech discrimination. Consequently, probe tube measurement should be used not only to adjust the frequency characteristics of the hearing aid but also to characterise the real effect of Automatic Gain Control AGC and Peak Clipping PC on insertion gain at higher input SPL. Multichannel hearing aids should be used whenever possible to reduce the disturbances to speech discrimination at low frequencies.
Pitch for nonsimultaneous successive harmonics in quiet and noise.
Pitch perception was studied with respect to nonsimultaneous successive harmonics of fundamentals in quiet and noise. Stimuli consisted of three nonoverlapping sine waves each of 40-msec duration. Pitch perception, examined by discrimination and matching, was found to correspond to spectral frequency in quiet and fundamental frequency in noise. The results suggest a pitch processor that integrates over time (synthetic mode) in noise and analyzes spectral components (analytic mode) in quiet. The findings are discussed with respect to current theories of pitch perception and auditory integrative functions. The findings are thought to be particularly relevant to analytic and synthetic modes of pitch perception.
Evaluation of multi-attribute auditory discrimination in dyslexia with the mismatch negativity.
OBJECTIVE: Dyslexia is associated with impairments in the phonological system or with more general auditory dysfunctions. We determined the discrimination of 5 sound contrasts (pitch, duration, intensity, location, and the presence of a gap) in dyslexia with the mismatch negativity (MMN). METHODS: We compared MMNs of 9 adult dyslexic and 11 control subjects with a new 5-deviant paradigm which enables one to assess the discrimination of each of these features in 15 min. Also, a control oddball condition with pitch and duration deviants was included. In the new paradigm, all deviant stimuli are presented in the same stimulus block so that the standard stimuli, of which there are 50%, alternate with the deviant stimuli. RESULTS: In the 5-deviant paradigm, a diminished pitch-MMN and an enhanced location-MMN were found in dyslexic individuals. Furthermore, pitch and duration MMNs in this and in the oddball paradigms suggested that smaller MMNs are elicited in the new than oddball paradigm in dyslexic subjects. CONCLUSIONS: Pitch discrimination is impaired in dyslexia. However, location discrimination, not addressed previously with MMN, is enhanced. Furthermore, dyslexic subjects are more impaired in detecting changes in sound streams with than without variation. SIGNIFICANCE: In dyslexia research, the new 5-deviant MMN paradigm is feasible and even more sensitive than the traditional oddball paradigm.
A cross-linguistic PET study of tone perception in Mandarin Chinese and English speakers.
PET was used in a cross-linguistic study to determine whether neural mechanisms subserving pitch perception differ as a function of linguistic relevance. We compared tone perception in 12 native Mandarin speakers, who use tonal patterns to distinguish lexical meaning, with that of 12 native speakers of a nontone language, English. Subjects were scanned under two conditions: a silent resting baseline and a tonal task involving discrimination of pitch patterns in Mandarin words. Both groups showed common regions of CBF increase, but only Mandarin speakers showed additional activation in frontal, parietal, and parieto-occipital regions of the left hemisphere; this latter finding indicates that language experience may influence brain circuitry in the processing of auditory cues. In contrast, only the English group showed activity in the right inferior frontal cortex, consistent with a right-hemispheric role in pitch perception.
Heart rate and disjunctive reaction time: the effects of discrimination requirements.
Explore the source record for details and available documents.
Frequency discrimination ability of hearing-impaired listeners: a reassessment.
Explore the source record for details and available documents.
The role of envelope beat cues in the detection and discrimination of second-order amplitude modulation.
Explore the source record for details and available documents.