Complex Pitch Research Articles

Physiological observations on the neural representation of complex pitch

Pitch models which depend on the manner in which the frequencies of pitch‐evoking stimuli are encoded in the temporal discharge patterns of neurones in the auditory periphery, would be easier to test if it were possible to predict the temporal discharge patterns in response to such complex stimuli. As an extreme case, the effects of variants of the click trains, whose pitch has been the subject of controversy between Whitfield and Moore (see Evan's chapter in Hearing—Psychological Bases and Psychophysics, edited by R. Klinke and R. Hartmann (Springer, New York, 1985) have been studied at the level of the cat's cochlear nerve. In particular, the following stimuli have been used on fibers with characteristic frequencies up to 4 kHz: pulse trains with even intervals of 5, 10, 20 ms; uneven intervals of 4.5/5.5 ms, 4.6/5.4 ms, 4.8/5.2 ms, and even intervals of 2.5 and 5 ms with alternate click phases. Autocorrelations have been performed of the spike discharge patterns evoked by the stimuli. To a first approx...

Effect of frequency, timbre, experience, and feedback on musical tuning skills.

Subjects with tuning experience were superior to nontuners in a pitch-matching task at all but the lowest of five frequencies tested. Performance was better for adjustment of simple (sine-wave) tones to match simple tones than for adjustment of complex (string-timbre) tones to match simple tones. A comparison of constant errors showed that both tuners and nontuners heard complex tones as sharp relative to simple tones. Additional testing with 2 of the subjects indicated that the first overtone of the complex tone was sufficient to produce this effect. Repetition of the pitch-matching task over 6 days produced some improvement in performance. A second experiment showed that auditory and visual feedback improved tuning accuracy for complex comparison tones about 4.5 cents more than did practice without feedback, but no effect was observed for simple comparison tones. This experiment also indicated that musical experience, rather than tuning experience perse, was responsible for the effects of prior experience, and that tuning was more accurate when the standard was a complex tone and when the standard and comparison tones had the same timbre. The relevance of these data to musical tuning skills and to theories of complex pitch perception is discussed.

Infant pitch perception: evidence for responding to pitch categories and the missing fundamental.

While numerous studies on infant perception have demonstrated the infant's ability to discriminate sounds having different frequencies, little research has evaluated more sophisticated pitch perception abilities such as perceptual constancy and perception of the missing fundamental. In the present study 7-8-month-old infants demonstrated the ability to discriminate harmonic complexes from two pitch categories that differed in pitch by approximately 20% (e.g., 160 vs 200 Hz). Using a visually reinforced conditioned head-turning paradigm, a number of spectrally different tonal complexes that contained varying harmonic components but signaled the same two pitch categories were presented. After learning the basic pitch discrimination, the same infants learned to categorize spectrally different tonal complexes according to the pitches signaled by their fundamental frequencies. That is, the infants showed evidence of perceptual constancy for the pitch of harmonic complexes. Finally, infants heard tonal complexes that signaled the same pitch categories but for which the fundamental frequency was removed. Infants were still able to categorize the harmonic complexes according to their pitch categories. These results suggest that by 7 months of age infants show fairly sophisticated pitch perception abilities similar to those demonstrated by adults.

Impaired pitch matching for different waveforms after right hemisphere damage

Studies of dichotic pitch discrimination in normal and neurologically impaired subjects have suggested that the nondominant hemisphere plays a significant role in complex pitch perception. However, despite the fact that pitch deficits can typically be demonstrated in patients with right hemisphere damage, such patients rarely report gross difficulties with functions that use pitch information, suggesting that some capacity for this process is spared. To test this, a series of pitch matching tests were administered to a 61‐year‐old subject who suffered a right hemisphere stroke, and was found to have normal speech but impaired pitch discrimination on dichotic testing. The frequency of one function generator was controlled by the subject and the frequency of a second generator that produced the target was controlled by the experimenter. Tones were presented continuously at 60 dBA, and the subject was free to alternate between the target and matching tones. Four conditions were tested: sine waves were matche...

Models of the perception of the pitch of tonal complexes

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Accuracy and perceptual asymmetry during dichotic pitch discrimination

Dichotic listening studies with normal right‐handed listeners and with patients who have suffered focal cortical lesions suggest that the right hemisphere plays an important role in complex pitch discrimination. The perceptual asymmetry observed in normal listeners was studied using a dichotic recognition test consisting of 500‐ms square wave tones with fundamental frequencies corresponding to the 12 semitones in the octave 261.63–523.25 Hz. A diotic recognition probe followed the presentation of each dichotic pair. The probe was identical to one of the dichotic items on 50% of the trials. On the remaining trials, the probe differed from one of the dichotic items by 0.25, 0.50, 0.75, or 1.00 semitone. Subjects who demonstrated a left ear advantage on this test were significantly more accurate in their pitch discrimination than were subjects who demonstrated a right ear advantage. Within each group, left and right discrimination functions were similar. The right ear advantage for pitch discrimination may reflect a sub‐optimal strategy for processing pitch or for selecting dichotic signals. [Supported by NIH.]

PET imaging during auditory stimulation

Positron emission tomography (PET) provides a means of studying regional brain activity in vivo. PET measurements of regional cerebral blood flow (rCBF) were obtained in 3 subjects with normal hearing during the continuous inhalation of CO15O. A nominally unstimulated 3‐min period, during which a moderate level of apparatus noise was present, was followed by the continuous binaural presentation of white noise (3 min). In addition, dichotic stop‐consonant and complex pitch discrimination tests (3 min) were administered to two subjects. White noise produced 10%–15% and 15%–25% increases in rCBF in the temporal lobes and thalamus, respectively. Increases were also observed in nonauditory structures: 10%–25% in medial frontal cortex and 5%–10% in medial occipital cortex. In contrast, maximum changes in rCBF during speech and pitch discrimination were of smaller magnitude and occurred over more restricted cortical regions. These results suggest that continuous white noise produces significant increases in rCBF...

Multiple pitch induced by frequency modulation of partials of complex tones

The stimuli were complex tones consisting of the first 12 harmonics of 100 Hz, with duration of 1.5 s. The even-numbered harmonics of the complex had a linearly falling or linearly rising spectral envelope and were frequency modulated by either a sinusoid with 90° or 270° phase or by a linear ramp. Frequency and depth of modulation were 0.66 Hz (1.0 cycle/1.5 s) and 6%,respectively. The odd-numbered harmonics had a flat spectral envelope and were frequency modulated by a 0° phase sinusoid with frequencies of 0.3, 0.66, or 2.0 Hz, and depths of 3, 6, or 10%. In agreement with McAdams [J. Acoust. Soc. Am. Suppl. 1 68, S109 (1980)], we observed that when a different modulation function is impressed upon each subset of harmonics, the 12-component complex is perceived as having two pitch values, which seem to correspond to those of the individual subsets of harmonics when presented in isolation. An absolute identification experiment was conducted in which listeners were asked to identify the spectral envelope (timbre) and pattern of frequency modulation of the even-numbered harmonics of the 12-component complex. Accuracy of identification ranged from 40%–75% over the various stimulus conditions. In a second experiment, listeners were asked to judge the strength of the periodicity pitch of two-tone complexes (2500 and 3000 Hz, or 500 and 600 Hz) in which only the higher partial was frequency modulated by a linear ramp with frequency of 1.0 cycle per signal duration. Preliminary results suggest that the periodicity pitch of the two-tone complex becomes weaker as modulation depth increases. The relation between the perceptual data and the time and frequency domain characteristics of the signals will be discussed.

Predicting brain organization from dichotic listening performance: Cortical and subcortical functional asymmetries contribute to perceptual asymmetries

The patterns of perceptual asymmetry elicited by dichotic speech and complex pitch stimuli were evaluated in a group of 28 normal, right-handed subjects. As in previous studies, between 70 and 75% of the subjects showed a right-ear advantage for speech and left-ear advantage for pitch. However, less than half of the subjects (46%) showed the expected pattern on both tests. It is argued that the assumption of symmetrical, contralateral auditory pathway superiority during dichotic stimulation is only appropriate in roughly half of the dextral population. In the remaining half, significant subcortical asymmetries and/or a lack of contralateral advantage appear to be present. The assessment of complementary cortical functions should provide a way to reduce the confounding of cortical and subcortical contributions to auditory perceptual asymmetries, and thus provide a more accurate behavioral index of brain organization.

Noise-induced shifts in the pitch of pure and complex tones

The influence of masking noise on the pitch of dichotic two-tone complexes and on the pure-tone pitches of their spectral components is investigated by matching both to the pitch of a binaural periodic pulse comparison signal. It is found that noise-induced shifts in the pitch of pure tones are considerably larger than induced shifts in complex tone or ’’residue’’ pitch. A pitch matching experiment with pure tones and contralateral noise reveals a general, central effect of noise on pitch. If empirical pitch matching data are corrected for this central effect, complex-tone pitch is found to be independent of the influence of masking noise, whereas pure-tone pitch remains subject to significant induced shifts. This finding is inconsistent with some of the modern pitch theories. It is consistent with the notion that pure-tone pitch is mediated by spatial, and complex-tone pitch by temporal encoding in peripheral auditory units.

Vocal pitch production in a patient with expressive dysprosody: A possible right hemisphere role in speech production

Recent evidence obtained from normal listeners, from neurological patients with focal cortical lesions, and from patients who have undergone surgical section of the corpus callosum suggests that the right hemisphere auditory system has an advantage over the left in the perception of complex pitch. A possible production correlate was studied in a patient with right hemisphere tumor in whom speech was monotonic. On binaural testing, both speech and complex pitch discrimination were intact. On dichotic testing, a significant impairment was observed on pitch, but not speech discrimination. Vocal pitch control was assessed by having the patient mimic the pitch of a binaurally presented token frequency. A range of 100 to 240 Hz was tested at 20-Hz intervals. The patient's production was limited to a range of approximately 24 Hz, centered around 140 Hz. The modulation of vocal pitch in the production of intonation contour may be one way in which right hemisphere mechanisms contribute to the production of speech. [Work supported by NIH grants NS03346-19 and RR05396-20.]

Pitch of unequal-amplitude dichotic two-tone harmonic complexes.

Melodic interval identification experiments are reported for dichotic tone complexes of two successive random harmonics having different intensity ratios. Experimentally obtained confusion matrices are compared with theoretical matrices derived from Goldstein's optimal processor theory. Wightman's pattern transformation theory, and a newly formulated analytic pitch theory. Results confirm that at relatively low harmonic numbers, the optimal processor theory provides an excellent description of the empirical data, even for large inter-tone intensity differences, but that for complex tones of higher harmonic order analytic pitch perception plays a significant role. At harmonic numbers higher than about six, none of the examined theories or combinations of theories gives a complete account of empirical data, which underscores the fact that aural processing of complex tones is still not well understood.

Complex pitch perception after callosal section: Further evidence for a right hemisphere mechanism

It has recently been suggested that right hemisphere auditory function provides a mechanism for complex pitch perception. This possibility was examined in two patients who underwent surgical section of the corpus callosum. Both patients were right handed, had bilaterally normal hearing, and were assessed to have left hemisphere language dominance. Each patient was tested using the Complex Tone Test, which consists of 112 trials in which a dichotic pair of 550-ms square wave stimuli are followed after 1 s by a binaural probe item. Subjects responded manually, indicating whether or not the probe matched either dichotic item. Both patients revealed above average accuracy on left ear stimuli, but performance on right ear stimuli that was significantly worse than chance. This pattern of results is similar to that found for dichotically presented speech stimuli, but in the opposite direction. These data add further support to the claim that the right hemisphere provides a mechanism for complex pitch perception. [Work supported by USPHS grant number 2 R01 NS15053-02 and the Alfred P. Sloan Foundation.]

The complex tone test: Implications for the assessment of auditory laterality effects

The results obtained from 24 right-handed subjects on a dichotic pitch recognition test were analyzed with respect to the magnitude, stability and incidence of right hemisphere advantage indicating that complex pitch discrimination yields perceptual asymmetries comparable to those observed for speech perception, but in the opposite direction. The effects of stimulus competition on the magnitude of laterality effects were also examined and a nearly threefold difference in the magnitude of the laterality measure was demonstrated as a function of acoustic features of the stimuli. The problem of attributing the magnitude of any perceptual asymmetry to a degree of lateralization of cortical function is discussed.

Musical pitch of two-tone complexes and predictions by modern pitch theories.

Most studies of the musical pitch of harmonic tone complexes have utilized signals comparing two or more successive harmonics. The present study provides systematic data on melodic interval recognition by three musically experienced subjects with sounds whose missing fundamentals were represented by two nonsuccessive harmonics nf0,(n + m)f0, delivered to separate ears. Data were obtained in the ranges 1 less than or equal to n less than or equal to 9, 2 less than or equal to m less than or equal to 4, and 200 Hz less than or equal to f0 less than or equal to 1000 Hz. The data are interpreted in the light of three theories, the "optimum processor theory," the "virtual pitch theory," and the "pattern transformation theory." For each theory, a constraint on preformance is proposed based on interference between the "analytic" and "synthetic" pitch perception modes. The former is obtained with large spacings between harmonics, where listeners are more likely to perceive harmonics as individual tones, each having their own pitch. This degrades the listener's ability to hear the fundamental pitch.

Dichotic pitch extraction: Spectral limits of the contribution of the two ears to the dichotic pitch

A binaural complex consisting of two dichotically presented tones close in frequency will have a pitch different from that of either component presented monaurally. The object of the present experiment was to study the pitch of the binaural complex as a function of both interaural intensity difference and the bandwidth of one of the dichotic components. The dichotic stimulus consisted of a 100‐ms burst of narrow‐band noise centered at 1700 Hz and of a simultaneous, 100‐ms pure tone having its frequency fixed either at 1650 or 1750 Hz. Using a modified Method‐of‐Adjustments procedure, the listeners matched the pitch of various dichotic tone‐noise complexes to that of a binaural tone of variable frequency. Results indicate that the effective bandwidth of the monaural components contributing to the pitch of such complexes corresponds to that of the Critical Band. Relevance of the data to a central pitch processor theory will be discussed. [Work supported by the Veterans Administration.]

Pitch of two‐tone complexes comprising nonsuccessive harmonics

Most studies of the musical pitch of harmonic tone complexes have utilized signals comprising two or more successive harmonics. It is also easily observed that tones from a clarinet, whose even harmonics are heavily suppressed, evoke a strong and unambiguous pitch. The present study provides systematic data on melodic interval recognition by three musically experienced subjects, with sounds made up of two nonsuccessive harmonics. If we describe such a two‐tone complex as nf0, (n + m)f0, data were obtained for the ranges 1 ⩽ n ⩽ 10, 2 ⩽ m ⩽ 4, 200 ⩽ f0 ⩽ 1000 Hz. Trends in the data are interpreted in the light of three popular models, the “optimum processor theory” (Goldstein), the “pattern transformation theory” (Wightman), and the “learning matrix theory” (Terhardt). A constraint on performance is proposed which is based on the “analytic” and “synthetic” perception modes of complex tones (Helmholtz). Apparently, when the harmonic spacing increases, the listener is more likely to operate in the analytic mode, perceiving harmonics as individual tones each having its own pitch. This degrades the tracking ability for the missing fundamental. [Work partially supported by NIH.]

Ear dominance of dichotic chords and ear superiority in frequency discrimination.

Frequency-discrimination thresholds were determined for pure tones presented either to the right or to the left ear of experienced listeners. In some conditions the stimulus was monaural, whereas in others a tone of fixed, different frequency was simultaneoulsy present in the contralateral ear. Center frequencies of 1.2, 1.7, and 3.2 kHz were investigated. Results reveal a small but reliable discrepancy between just noticeable frequency differences obtained for the right and for the left ear, both in the monaural and in the dichotic conditions. Furthermore, the direction and the degree of asymmetry with respect to the frequency resolving power of the two ears showed a correlation with the direction and the degree of ear dominance for the pitch of dichotic two-tone complexes. [See Efron and Yund, J. Acoust. Soc. Am. 59, 889–898 (1976).] Implications of the relationship between the two types of functional asymmetry of the auditory system are discussed.

Pitch of two-tone complexes

Helmholtz reported that the pitch of a two component complex tone could be shifted by slightly increasing the amplitude of one component. The pitch was shifted toward the frequency of the more intense component. Helmholtz attributed the pitch shift to a variation in the instantaneous frequency of the two tone complex. This laboratory has previously investigated the discriminability of pairs of two component complex tones with identical small amplitude differences between the components of a pair. Discriminability seemed to depend upon the difference in their envelope-weighted instantaneous frequency fluctuations. In the study to be reported, we have asked listeners to match a two component, nonfluctuating complex tone to each member of pairs of the two component complex tones described above. The differences in pitch so obtained will be compared with the differences in envelope-weighted instantaneous frequency fluctuations to relate the pitch of each fluctuating two tone complex to its averaged instantaneous frequency. [Work supported by a grant from the National Institutes of Health.]

Macrophage infiltration of breast tumours: a prospective study.

In 50 cases of infiltrating breast cancer investigated in a prospective study the number of macrophages within each tumour was assessed. The macrophages were identified by their cytoplasmic acid phosphatase activity. The number of lymphocytes and plasma cells within the tumours were graded by a scoring technique. Significantly fewer cases with metastases were found among those with high macrophage and plasma cell scores. There was no correlation between lymphoreticular infiltration and the degree of tumour differentiation, but in cases without metastases the lymphoreticular infiltration between tumour cells was nearly always only slight when the macrophage score was low.