Physiological correlates of the perceptual pitch shift for sounds with similar waveform autocorrelation
01 Jan 2004-Acoustics Research Letters Online-arlo (Acoustical Society of America)-Vol. 5, Iss: 1, pp 1-6
TL;DR: A perceptual experiment shows that random click trains with a uniform interclick distribution can be reliably pitch-matched to pseudo-periodic click trains and similar cues are found in either first-order or all-order interspike interval statistics.
Abstract: A perceptual experiment shows that random click trains with a uniform interclick distribution can be reliably pitch-matched to pseudo-periodic click trains. The pitch matches cannot be explained on the basis of mean rate, power spectrum, or autocorrelation of the waveform. The matches are qualitatively, but not quantitatively, consistent with the most common interspike interval present in responses of single units from the ventral cochlear nucleus of anaesthetised guinea pigs. The physiological recordings also demonstrate that at the level of the cochlear nucleus, similar cues are found in either first-order or all-order interspike interval statistics.
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01 Jan 2005
TL;DR: This chapter discusses models of pitch, old and recent, to chart their common points – many are variations on a theme – and differences, and build a catalog of ideas for use in understanding pitch perception.
Abstract: This chapter discusses models of pitch, old and recent. The aim is to chart their common points – many are variations on a theme – and differences, and build a catalog of ideas for use in understanding pitch perception. The busy reader might read just the next section, a crash course in pitch theory that explains why some obvious ideas don’t work and what are currently the best answers. The brave reader will read on as we delve more deeply into the origin of concepts, and the intricate and ingenious ideas behind the models and metaphors that we use to make progress in understanding pitch.
229 citations
TL;DR: This study presents an idealized neurocomputational model, which provides a unified account of the multiple time scales observed in pitch perception and suggests a key role for efferent connections from central to sub-cortical areas in controlling the temporal dynamics of pitch processing.
Abstract: Pitch is one of the most important features of natural sounds, underlying the perception of melody in music and prosody in speech. However, the temporal dynamics of pitch processing are still poorly understood. Previous studies suggest that the auditory system uses a wide range of time scales to integrate pitch-related information and that the effective integration time is both task- and stimulus-dependent. None of the existing models of pitch processing can account for such task- and stimulus-dependent variations in processing time scales. This study presents an idealized neurocomputational model, which provides a unified account of the multiple time scales observed in pitch perception. The model is evaluated using a range of perceptual studies, which have not previously been accounted for by a single model, and new results from a neurophysiological experiment. In contrast to other approaches, the current model contains a hierarchy of integration stages and uses feedback to adapt the effective time scales of processing at each stage in response to changes in the input stimulus. The model has features in common with a hierarchical generative process and suggests a key role for efferent connections from central to sub-cortical areas in controlling the temporal dynamics of pitch processing.
56 citations
TL;DR: A mechanism by which delays may be synthesized from cross-channel phase interaction is proposed by which Phases of adjacent cochlear filter channels are shifted by an amount proportional to frequency and then combined as a weighted sum to approximate a delay.
Abstract: Temporal models of pitch and harmonic segregation call for delays of up to 30ms to cover the full range of existence of musical pitch. To date there is little anatomical or physiological evidence for delays that long. We propose a mechanism by which delays may be synthesized from cross-channel phase interaction. Phases of adjacent cochlear filter channels are shifted by an amount proportional to frequency and then combined as a weighted sum to approximate a delay. Synthetic delays may be used by pitch perception models such as autocorrelation, segregation models such as harmonic cancellation, and binaural processing models to explain sensitivity to large interaural delays. The maximum duration of synthetic delays is limited by the duration of the impulse responses of cochlear filters, itself inversely proportional to cochlear filter bandwidth. Maximum delay is thus frequency dependent. This may explain the fact, puzzling for temporal pitch models such as autocorrelation, that pitch is more salient and eas...
50 citations
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TL;DR: A review of the psychophysical study of pitch perception can be found in this article, where the authors show that the pitch of complex stimuli is likely based on the temporal regularities in a sound's waveform, with the strongest pitches occurring for stimuli with low-frequency components.
Abstract: This article is a review of the psychophysical study of pitch perception. The history of the study of pitch has seen a continual competition between spectral and temporal theories of pitch perception. The pitch of complex stimuli is likely based on the temporal regularities in a sound’s waveform, with the strongest pitches occurring for stimuli with low-frequency components. Thus, temporal models, especially those based on autocorrelationlike processes, appear to account for the majority of the data.
42 citations
TL;DR: This study demonstrates that human perception of stimuli can be determined exclusively by temporal features of spike trains independent of the mean spike rate and without contribution from population response factors.
38 citations
Cites background from "Physiological correlates of the per..."
...Indeed, the phenomenon that inter-spike intervals of longer duration receive higher weights than short ones has been previously documented in the auditory system [14, 28]....
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References
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TL;DR: It is shown that the model can simulate new experimental results that show how the quality of the pitch percept is influenced by the resolvability of the harmonic components of the stimulus complex and it is not necessary to postulate two separate mechanisms to explain different pitch percepts associated with resolved and unresolved harmonics.
Abstract: A model of the mechanism of residue pitch perception is revisited. It is evaluated in the context of some new empirical results, and it is proposed that the model is able to reconcile a number of differing approaches in the history of theories of pitch perception. The model consists of four sequential processing stages: peripheral frequency selectivity, within-channel half-wave rectification and low-pass filtering, within-channel periodicity extraction, and cross-channel aggregation of the output. The pitch percept is represented by the aggregated periodicity function. Using autocorrelation as the periodicity extraction method and the summary autocorrelation function (SACF) as the method for representing pitch information, it is shown that the model can simulate new experimental results that show how the quality of the pitch percept is influenced by the resolvability of the harmonic components of the stimulus complex. These include: (i) the pitch of harmonic stimuli whose components alternate in phase; (ii) the increased frequency difference limen of tones consisting of higher harmonics; and (iii) the influence of a mistuned harmonic on the pitch of the complex as a function of its harmonic number. To accommodate these paradigms, it was necessary to compare stimuli along the length of the SACF rather than relying upon the highest peak alone. These new results demonstrate that the model responds differently to complexes consisting of low and high harmonics. As a consequence, it is not necessary to postulate two separate mechanisms to explain different pitch percepts associated with resolved and unresolved harmonics.
432 citations
"Physiological correlates of the per..." refers background in this paper
...A simple distance measure between histograms (Meddis and O’Mard, 1997) would lead to a prediction more in line with the magnitude of the effect....
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TL;DR: In this article, four experiments were reported that deal with pitch perception of harmonic complex tones containing up to 11 successive harmonics, and the question was raised whether the pitch percept of the missing fundamental is mediated only by low-order resolvable harmonics or whether it can also be conveyed by high-order harmonics that the cochlea fails to resolve.
Abstract: Four experiments are reported that deal with pitch perception of harmonic complex tones containing up to 11 successive harmonics. In particular, the question is raised whether the pitch percept of the missing fundamental is mediated only by low‐order resolvable harmonics, or whether it can also be conveyed by high‐order harmonics that the cochlea fails to resolve. Melodic interval identification performance was found to remain significantly above chance level even if the range of harmonics extended from the 20th to the 30th. Just‐noticeable differences (jnd) in the pitch of the missing fundamental were found to increase with increasing harmonic order, but to level off when all harmonics are above the 12th. These results are consistent with the notion of the existence of two distinct neural pitch mechanisms in the auditory system, but are, in principle, also compatible with a single central‐spectrum mechanism that uses the interspike interval histograms of auditory‐nerve fibers as inputs.
340 citations
TL;DR: This paper addresses the neural correlates of stimuli that produce more complex patterns of pitch judgments, such as shifts in pitch and multiple pitches, and investigates the relation between pitches associated with periodicity and those associated with click rate.
Abstract: 1. The neural correlates of low pitches produced by complex tones were studied by analyzing temporal discharge patterns of auditory nerve fibers in Dial-anesthetized cats. In the previous paper it was observed that, for harmonic stimuli, the most frequent interspike interval present in the population of auditory nerve fibers always corresponded to the perceived pitch (predominant interval hypothesis). The fraction of these most frequent intervals relative to the total number of intervals qualitatively corresponded to strength (salience) of the low pitches that are heard. 2. This paper addresses the neural correlates of stimuli that produce more complex patterns of pitch judgments, such as shifts in pitch and multiple pitches. Correlates of pitch shift and pitch ambiguity were investigated with the use of harmonic and inharmonic amplitude-modulated (AM) tones varying either in carrier frequency or modulation frequency. Pitches estimated from the pooled interval distributions showed shifts corresponding to "the first effect of pitch shift" (de Boer's rule) that is observed psychophysically. Pooled interval distributions in response to inharmonic stimulus segments showed multiple maxima corresponding to the multiple pitches heard by human listeners (pitch ambiguity). 3. AM and quasi-frequency-modulated tones with low carrier frequencies produce very similar patterns of pitch judgments, despite great differences in their phase spectra and waveform envelopes. Pitches estimated from pooled interval distributions were remarkably similar for the two kinds of stimuli, consistent with the psychophysically observed phase invariance of pitches produced by sets of low-frequency components. 4. Trains of clicks having uniform and alternating polarities were used to investigate the relation between pitches associated with periodicity and those associated with click rate. For unipolar click trains, where periodicity and rate coincide, physiologically estimated pitches closely follow the fundamental period. This corresponds to the pitch at the fundamental frequency (F0) that is heard. For alternating click trains, where rate and periodicity do not coincide, physiologically estimated pitches always closely followed the fundamental period. Although these pitch estimates corresponded to periodicity pitches that are heard for F0s > 150 Hz, they did not correspond to the rate pitches that are heard for F0s 150 Hz. Pitches for high-pass-filtered alternating click trains were estimated from pooled responses of fibers with characteristic frequencies (CFs) > 2 kHz. Roughly equal numbers of intervals at 1/rate and 1/F0 were found for all F0s studied, from 80 to 160 Hz, producing pitch estimates consistent with the rate pitches that are heard after high-pass filtering. The existence region for rate pitch also coincided with the presence of clear periodicities related to the click rate in pooled peristimulus time histograms. These periodicities were strongest for ensembles of fibers with CFs > 2 kHz, where there is widespread synchrony of discharges across many fibers. 6. The "dominance region for pitch" was studied with the use of two harmonic complexes consisting of harmonics 3-5 of one F0 and harmonics 6-12 of another fundamental 20% higher in frequency. When the complexes were presented individually, pitch estimates were always close to the fundamental of the complex. When the complexes were presented concurrently, pitch estimates always followed the fundamental of harmonics 3-5 for F0s of 150-480 Hz. For F0s of 125-150 Hz, pitch estimates followed one or the other fundamental, and for F0s < 125 Hz, pitch estimates followed the fundamental of harmonics 6-12. (ABSTRACT TRUNCATED)
312 citations
"Physiological correlates of the per..." refers background or result in this paper
...The autocorrelation of the waveform predicts the pitch and pitch strength of many deterministic or stochastic signals (Cariani and Delgutte, 1996; Yost 1996) and gives qualitatively similar results to all-order interspike interval distributions in populations of auditory nerve fibers (Cariani and Delgutte, 1996)....
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...The peak in autocorrelations of auditory nerve spike trains was found to produce correct pitch estimates for a wide range of stimuli (Cariani and Delgutte, 1996)....
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TL;DR: The results for chopper units suggest a model for stellate cells in which a regularly firing action potential generator is driven by the summation of the AN inputs to the cell, where the summations is low-pass filtered by the membrane capacitance of the cell.
Abstract: 1. The responses of neurons in the ventral cochlear nucleus (VCN) of decerebrate cats are described with regard to their regularity of discharge and latency. Regularity is measured by estimating th...
263 citations
"Physiological correlates of the per..." refers methods in this paper
...We used the coefficient of variation of the discharge regularity to classify a unit as primary-like or chopper (Young et al., 1988)....
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TL;DR: A computational auditory model that extracts pitch information with autocorrelation can reproduce all of the observed effects, provided the contribution of longer time intervals is progressively reduced by a linear weighting function that limits the mechanism to time intervals of less than about 33 ms.
Abstract: An objective melody task was used to determine the lower limit of melodic pitch (LLMP) for harmonic complex tones. The LLMP was defined operationally as the repetition rate below which listeners could no longer recognize that one of the notes in a four-note, chromatic melody had changed by a semitone. In the first experiment, the stimuli were broadband tones with all their components in cosine phase, and the LLMP was found to be around 30 Hz. In the second experiment, the tones were filtered into bands about 1 kHz in width to determine the influence of frequency region on the LLMP. The results showed that whenever there was energy present below 800 Hz, the LLMP was still around 30 Hz. When the energy was limited to higher-frequency regions, however, the LLMP increased progressively, up to 270 Hz when the energy was restricted to the region above 3.2 kHz. In the third experiment, the phase relationship between spectral components was altered to determine whether the shape of the waveform affects the LLMP. When the envelope peak factor was reduced using the Schroeder phase relationship, the LLMP was not affected. When a secondary peak was introduced into the envelope of the stimuli by alternating the phase of successive components between two fixed values, there was a substantial reduction in the LLMP, for stimuli containing low-frequency energy. A computational auditory model that extracts pitch information with autocorrelation can reproduce all of the observed effects, provided the contribution of longer time intervals is progressively reduced by a linear weighting function that limits the mechanism to time intervals of less than about 33 ms.
177 citations