The case of the missing delay lines: Synthetic delays obtained by cross-channel phase interaction
08 Jun 2006-Journal of the Acoustical Society of America (Acoustical Society of America)-Vol. 119, Iss: 6, pp 3908-3918
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...
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TL;DR: The current state-of-the-art in the understanding of the sensitivities of bilateral CI patients to binaural cues in electric hearing is reviewed, and the important issues and challenges as they relate to clinical practice and the development of new bINAural processing strategies are highlighted.
96 citations
Cites background from "The case of the missing delay lines..."
...For instance, the natural time that it takes for waves to physically travel along the basilar membrane is effectively bypassed in CI stimulation, which may affect binaural sensitivity that is thought to depend to some extent on these cochlear delays (De Cheveign e and Pressnitzer, 2006; Shamma et al., 1989)....
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...…the natural time that it takes for waves to physically travel along the basilar membrane is effectively bypassed in CI stimulation, which may affect binaural sensitivity that is thought to depend to some extent on these cochlear delays (De Cheveign e and Pressnitzer, 2006; Shamma et al., 1989)....
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TL;DR: The coding of complex sounds in the early auditory system has a 'standard model' based on the known physiology of the cochlea and main brainstem pathways, but between the early and late auditory system, the role of primary auditory cortex (A1) is still debated.
93 citations
TL;DR: Evidence of a relationship between fo discrimination performance and frequency selectivity in listeners with SNHL is provided, supporting "spectral" and "spectro-temporal" theories of pitch perception that rely on sharp tuning in the auditory periphery to accurately extract fo information.
Abstract: This study tested the relationship between frequency selectivity and the minimum spacing between harmonics necessary for accurate fo discrimination. Fundamental frequency difference limens (fo DLs) were measured for ten listeners with moderate sensorineural hearing loss (SNHL) and three normal-hearing listeners for sine- and random-phase harmonic complexes, bandpass filtered between 1500 and 3500 Hz, with fo's ranging from 75 to 500 Hz (or higher). All listeners showed a transition between small (good) fo DLs at high fo's and large (poor) fo DLs at low fo's, although the fo at which this transition occurred (fo,tr) varied across listeners. Three measures thought to reflect frequency selectivity were significantly correlated to both the fo,tr and the minimum fo DL achieved at high fo's: (1) the maximum fo for which fo DLs were phase dependent, (2) the maximum modulation frequency for which amplitude modulation and quasi-frequency modulation were discriminable, and (3) the equivalent rectangular bandwidth of the auditory filter, estimated using the notched-noise method. These results provide evidence of a relationship between fo discrimination performance and frequency selectivity in listeners with SNHL, supporting "spectral" and "spectro-temporal" theories of pitch perception that rely on sharp tuning in the auditory periphery to accurately extract fo information.
92 citations
TL;DR: The test provides a simple, quick, and robust way to measure sensitivity to TFS, and shows that, for normal-hearing subjects, learning effects are small, and the effect of the level of testing is also small.
Abstract: Recent evidence suggests that sensitivity to the temporal fine structure (TFS) of sounds is adversely affected by cochlear hearing loss. This may partly explain the difficulties experienced by people with cochlear hearing loss in understanding speech when background sounds, especially fluctuating backgrounds, are present. We describe a test for assessing sensitivity to TFS. The test can be run using any PC with a sound card. The test involves discrimination of a harmonic complex tone (H), with a fundamental frequency F0, from a tone in which all harmonics are shifted upwards by the same amount in Hertz, resulting in an inharmonic tone (I). The phases of the components are selected randomly for every stimulus. Both tones have an envelope repetition rate equal to F0, but the tones differ in their TFS. To prevent discrimination based on spectral cues, all tones are passed through a fixed bandpass filter, usually centred at 11F0. A background noise is used to mask combination tones. The results show that, for...
88 citations
TL;DR: Evidence is presented suggesting a partial dissociation between resolution in the excitation pattern and the ability to hear out a partial, and it is proposed that the latter requires information from temporal fine structure (phase locking).
73 citations
Cites methods from "The case of the missing delay lines..."
...…weighting functions used by Bernstein and Oxenham were essentially arbitrary, and were chosen to fit F0 discrimination data as a function of N. de Cheveigné and Pressnitzer (2006) proposed a model in which the delays that are required to perform operations such as autocorrelation are synthesized…...
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References
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Book•
01 Jan 1977
TL;DR: In this paper, the nature of sound and the structure and function of the auditory system are discussed, including absolute thresholds, frequency selectivity, masking and the critical band, and the perception of loudness.
Abstract: Preface to the Fifth Edition The nature of sound and the structure and function of the auditory system Absolute thresholds Frequency selectivity, masking and the critical band The perception of loudness Temporal processing in the auditory system Pitch perception Space perception Auditory pattern and object perception Speech perception Practical applications References Glossary Index
2,729 citations
1,513 citations
"The case of the missing delay lines..." refers methods in this paper
...In the models of Jeffress 1948 and Licklider 1951 , coincidence detectors are preceded by neural delays, that are also required by equalization-cancellation Durlach, 1963 , harmonic cancellation de Cheveigné, 1993 or strobed temporal integration Patterson et al., 1992 ....
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TL;DR: The high sensitivity and sharp-frequency tuning, as well as compression and other nonlinearities (two-tone suppression and intermodulation distortion), are highly labile, indicating the presence in normal cochleae of a positive feedback from the organ of Corti, the "cochlear amplifier."
Abstract: In mammals, environmental sounds stimulate the auditory receptor, the cochlea, via vibrations of the stapes, the innermost of the middle ear ossicles. These vibrations produce displacement waves that travel on the elongated and spirally wound basilar membrane (BM). As they travel, waves grow in amplitude, reaching a maximum and then dying out. The location of maximum BM motion is a function of stimulus frequency, with high-frequency waves being localized to the “base” of the cochlea (near the stapes) and low-frequency waves approaching the “apex” of the cochlea. Thus each cochlear site has a characteristic frequency (CF), to which it responds maximally. BM vibrations produce motion of hair cell stereocilia, which gates stereociliar transduction channels leading to the generation of hair cell receptor potentials and the excitation of afferent auditory nerve fibers. At the base of the cochlea, BM motion exhibits a CF-specific and level-dependent compressive nonlinearity such that responses to low-level, near-CF stimuli are sensitive and sharply frequency-tuned and responses to intense stimuli are insensitive and poorly tuned. The high sensitivity and sharp-frequency tuning, as well as compression and other nonlinearities (two-tone suppression and intermodulation distortion), are highly labile, indicating the presence in normal cochleae of a positive feedback from the organ of Corti, the “cochlear amplifier.” This mechanism involves forces generated by the outer hair cells and controlled, directly or indirectly, by their transduction currents. At the apex of the cochlea, nonlinearities appear to be less prominent than at the base, perhaps implying that the cochlear amplifier plays a lesser role in determining apical mechanical responses to sound. Whether at the base or the apex, the properties of BM vibration adequately account for most frequency-specific properties of the responses to sound of auditory nerve fibers.
1,423 citations
"The case of the missing delay lines..." refers background in this paper
...Frequency and phase characteristics are known to change with level Robles and Ruggero, 2001 ....
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...However measurements suggest that level affects mainly the relative amplitudes of the early and later segments of a chirp-shaped impulse response, leaving the temporal structure position of peaks and zero crossings invariant Carney et al., 1999; Robles and Ruggero, 2001; Shera, 2001 ....
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TL;DR: The value of the auditory-filter bandwidth continues to decrease as center frequency decreases below 500 Hz, and a method is described for calculating excitation patterns from filter shapes.
Abstract: Recent estimates of auditory‐filter shape are used to derive a simple formula relating the equivalent rectangular bandwidth (ERB) of the auditory filter to center frequency. The value of the auditory‐filter bandwidth continues to decrease as center frequency decreases below 500 Hz. A formula is also given relating ERB‐rate to frequency. Finally, a method is described for calculating excitation patterns from filter shapes.
941 citations
TL;DR: Basilar-membrane responses to single tones were measured, using laser velocimetry, at a site of the chinchilla cochlea located 3.5 mm from its basal end, and compressive growth of responses to tones with frequency near CF is accompanied by intensity-dependent phase shifts.
Abstract: Basilar-membrane responses to single tones were measured, using laser velocimetry, at a site of the chinchilla cochlea located 3.5 mm from its basal end. Responses to low-level ( 80 dB the largest responses are elicited by tones with frequency about 0.4–0.5 octave below CF. For stimulus frequencies well above CF, responses stop decreasing with increasing frequency: A plateau is reached. The compressive growth of responses to tones with frequency near CF is accompanied by intensity-dependent phase shifts. Death abolishes all nonlinearities, reduces sensitivity at CF by as much as 60–81 dB, and causes a relative phase lead at CF.
775 citations