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Results for “Pitch Perception”

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PubMed2006

Adaptation in the auditory space map of the barn owl.

Auditory neurons in the owl's external nucleus of the inferior colliculus (ICX) integrate information across frequency channels to create a map of auditory space. This study describes a powerful, sound-driven adaptation of unit responsiveness in the ICX and explores the implications of this adaptation for sensory processing. Adaptation in the ICX was analyzed by presenting lightly anesthetized owls with sequential pairs of dichotic noise bursts. Adaptation occurred in response even to weak, threshold-level sounds and remained strong for more than 100 ms after stimulus offset. Stimulation by one range of sound frequencies caused adaptation that generalized across the entire broad range of frequencies to which these units responded. Identical stimuli were used to test adaptation in the lateral shell of the central nucleus of the inferior colliculus (ICCls), which provides input directly to the ICX. Compared with ICX adaptation, adaptation in the ICCls was substantially weaker, shorter lasting, and far more frequency specific, suggesting that part of the adaptation observed in the ICX was attributable to processes resident to the ICX. The sharp tuning of ICX neurons to space, along with their broad tuning to frequency, allows ICX adaptation to preserve a representation of stimulus location, regardless of the frequency content of the sound. The ICX is known to be a site of visually guided auditory map plasticity. ICX adaptation could play a role in this cross-modal plasticity by providing a short-term memory of the representation of auditory localization cues that could be compared with later-arriving, visual-spatial information from bimodal stimuli.

Acoustic Stimulation↗
PubMed1983

The filled-duration illusion: limits of duration of interval and auditory fillers.

Two experiments were conducted to explore parameters of the filled-duration illusion, i.e., intervals filled with stimuli are perceived as longer than empty intervals of equal physical duration. It was hypothesized that the illusion would be found only for intervals of short duration, i.e., a few seconds, and that filled intervals would vary in perceived duration as a function of the type of "filler." Auditory tones were used as boundary and filler stimuli in a counterbalanced (Exp. I) and randomized (Exp. II) design that covered 9 intervals ranging from 1 to 60 sec. A psychophysical method of verbal estimation with single stimuli was employed. The first hypothesis was supported in that only with the short intervals (1 and 3 sec.) was there any evidence of a filled-duration illusion. The type of filler stimulus was important only in the 1-sec. intervals. Results are interpreted in terms of information-processing models for time perception.

Adolescent↗
PubMed2005

Investigations on the tonotopy for patients with a cochlear implant and a hearing aid.

OBJECTIVE: The aim of investigations was to compare the perception of the pitch of tonal signals by patients using both the cochlear implant and hearing aid. MATERIAL AND METHOD: The subjective evaluation of the pitch of sound presented through classical acoustic amplification and perceived by the residual hearing was compared with the sound perceived as a result of an electric stimulation. The subjects were 6 patients aged 15-63 (mean 38), diagnosed with postlingual deafness. The comparison of the acoustic signal transmitted via the hearing aid (in the acoustic free field) with the electrical signal from stimulated electrode of the cochlear implant enabled to determine subjectively evaluated shift in the frequency domain. The tonotopic distribution according to the Greenwood's model compared with the allocation of frequency determined on the basis of cochlear view was also investigated. RESULTS AND CONCLUSION: The study has revealed significant differences in the perception of the pitch of sounds perceived through the acoustic stimulation via the hearing aid and the electric stimulation via the implant.

Adolescent↗
PubMed1985

Acoustic chiasm II: Anatomical basis of binaurality in lateral superior olive of cat.

The afferent projections to the lateral superior olive (LSO) were examined with horseradish peroxidase, horseradish peroxidase-wheat germ agglutinin conjugate, 125I-wheat germ agglutinin and tritiated leucine autoradiograhy, anterograde axonal degeneration, and 14C-2-deoxyglucose methods. The pathway to the ipsilateral LSO orginates in the spherical cells in anteroventral cochlear nucleus. Although some of the fibers pass above the lateral nucleus of the trapezoid body, most pass below it and turn at right angles to enter the LSO either directly through its ventral, lateral, or dorsal borders, or through its ventral or dorsal hilus. They end in unpolarized terminal fields throughout the LSO. Most if not all of these fibers are true collaterals of axons continuing across the midline in the trapezoid body. Verifying Held's (1893) finding of a major direct projection from the cochlear nucleus to the contralateral medial nucleus of the trapezoid body (MTB) and Rasmussen's ('46) finding of a major projection from the MTB to the LSO, the present results illustrate that this two-neuron pathway probably supplies all but a very small component of the relatively direct input to the LSO from the contralateral ear. This pathway originates in the globular cells of the ventral cochlear nucleus and relays mostly though not exclusively through the "principal cells" in the more rostral parts of the MTB. It terminates mostly in perisomal endings in unpolarized fields throughout the LSO, though most heavily within the (high frequency) medial and middle limbs and less heavily in the LSO's (low frequency) lateral limb. In addition to this indirect pathway, there is a small direct pathway to the contralateral LSO as suggested by Goldberg and Brown ('69) and Warr ('72, '82). This direct pathway to the contralateral LSO, like the direct ipsilateral pathway, probably originates in the spherical cell region of the ventral cochlear nucleus, crosses the midline in the trapezoid body, and terminates in a small circumscribed area within the LSO's ventromedial (high frequency) area. The 2-deoxyglucose method applied to cats in which the ipsilateral and contralateral pathways have been surgically isolated shows that each of the pathways converging on the LSO is topographically and tonotopically organized with the ipsilateral and the combined contralateral terminations in strict tonotopic register.

Animals↗
PubMed1986

Effects of unilateral and bilateral cochlea removal on 2-deoxyglucose patterns in the chick auditory system.

The 2-deoxyglucose (2DG) method was used to map functional activity in the auditory system of chicks that had been subjected to unilateral or bilateral cochlea removal. Following survival times of 1 day to 4 weeks, chicks were exposed to continuous white noise in the 2DG experiments. In monaural subjects nucleus angularis and nucleus magnocellularis showed faint 2DG uptake on the side contralateral to the intact ear. In the binaural nucleus laminaris, the asymmetrical and almost mirror-imaged labeling pattern (Lippe, Stewart, and Rubel: Brain Res. 196:43-58, '80) was produced. The superior olive (OS) was strongly labeled on the ipsilateral side, whereas the contralateral OS showed only a slight 2DG uptake at its medial border. The lateral lemniscus and nucleus lemnisci lateralis, pars ventralis (LLv) showed stronger activation on the contralateral side. Both Nissl stains and 2DG patterns provide evidence that nucleus ventralis lemnisci lateralis (VLV) can be subdivided into an anterior (VLVa) and a posterior (VLVp) part. Whereas VLVp is labeled only contralaterally, VLVa is labeled on both sides with similar intensity. Nucleus mesencephalicus lateralis, pars dorsalis (MLD) is strongly labeled throughout contralaterally. The ipsilateral MLD shows a defined ventral portion of high 2DG uptake. Intensity of labeling here is symmetrical to the corresponding area of the contralateral MLD. These symmetrical patterns were related to the tonotopic organization of MLD, which was mapped in intact animals by using tone stimuli. Assuming that symmetrical 2DG uptake in monaural animals indicates excitatory input from both ears (EE-cells), it appears that these EE-cells occupy a sector of each isofrequency plane in MLD. Nucleus ovoidalis (Ov) generally was stronger labeled on the contralateral side. The columnar organization of field L as seen in monaural chicks has already been described (Scheich, Exp. Brain Res. 51:199-205, '83). In bilaterally deafened chicks, MLD, Ov, and layer L2 of field L showed strong but spatially restricted 2DG accumulation in contrast to absence of labeling in peripheral nuclei. The 2DG patterns in monaural chicks are likely to reflect excitatory input within the auditory system. In addition they reveal new insights into the functional organization of some of its nuclei. In particular, they support the notion that MLD contains maps of several interaural integration mechanisms similar to field L. Labeling in the auditory system of bilaterally deafened chicks may result from descending projections or from other than auditory inputs.

Animals↗
PubMed1982

[Design and methodology in environmental acoustics].

On the basis of many experiments of urban acoustics carried out in the canton of Geneva, the authors come to the conclusion that the normative values cannot be applied when the estimate of discomfort level is concerned. They must be applied to prevent the risk of auditive acuteness loss. In order to establish discomfort, it is necessary to use methods to measure and analyse the results which are suitable for each condition, and to take into account the acoustic charge, the noise dynamics, the acoustic spectrum and the socio-economic environment of the people concerned. The conception has been accepted by Court of Justice in Geneva, which is now legally accepted: one may consider a uncomfortable any increase of 4-6 dB(A) of the acoustic level, as compared to the previous situation or to the background noise. The ability to differentiate between two stimuli is based on the physiological mechanisms of hearing.

Acoustics↗
PubMed1985

Some neural mechanisms in the cat's auditory cortex underlying sensitivity to combined tone and wide-spectrum noise stimuli.

In the auditory cortex of nitrous oxide-anesthetized, muscle-relaxed cats, single neurons were studied for their responsiveness to pure tones that were mixed acoustically with simultaneously gated wide-spectrum noise bursts presented using a calibrated sealed stimulating system. The intensities of both the tone and the noise were systematically varied, with a view to ascertaining the sensitivity of cortical cells to a characteristic frequency tone delivered in the presence of a noise mask. Neurons for which wide-spectrum noise provided a net excitatory influence typically displayed a 'strong-signal capture' effect; that is, the cell's responses were dominated by whichever of the two elements of the combined stimulus was the more effective when tested separately. These cells generally had monotonic tone rate intensity functions. Most of the cells that were suppressed by the noise displayed nonmonotonic pure tone rate intensity functions. When nonmonotonic cells were studied with the combined stimulus, the noise was found to produce an intensity-dependent suppression of their tone-evoked responses that could not be overcome by elevating the tone intensity. In contrast, for the minority of monotonic neurons whose tone-evoked responses were suppressed by noise, that suppression could be overcome by raising the tone intensity. None of the cells in the sample responded in a sustained fashion to continuous noise. In each of 11 cases examined, the effect of a continuous noise mask was to elevate tone thresholds and to prolong latent periods for tones; the magnitude of both of these effects depended on the intensity of the continuous noise mask.

Animals↗
PubMed2006

The nature of music from a biological perspective.

Music, as language, is a universal human trait. Throughout human history and across all cultures, people have produced and enjoyed music. Despite its ubiquity, the musical capacity is rarely studied as a biological function. Music is typically viewed as a cultural invention. In this paper, the evidence bearing on the biological perspective of the musical capacity is reviewed. Related issues, such as domain-specificity, innateness, and brain localization, are addressed in an attempt to offer a unified conceptual basis for the study of music processing. This scheme should facilitate the study of the biological foundations of music by bringing together the fields of genetics, developmental and comparative research, neurosciences, and musicology.

Auditory Perception↗
PubMed2006

Frequency organization of the 40-Hz auditory steady-state response in normal hearing and in tinnitus.

We used the 40-Hz auditory steady-state response (SSR) to compare for the first time tonotopic frequency representations in the region of primary auditory cortex (PAC) between subjects with chronic tinnitus and hearing impairment and normal hearing controls. Frequency representations were measured in normal hearing (n=17) and tinnitus (n=28) subjects using eight carrier frequencies between 384 and 6561 Hz, each amplitude modulated (AM) at 40-Hz on trials of 3 min duration under passive attention. In normal hearing subjects, frequency gradients were observed in the medial-lateral, anterior-posterior, and inferior-superior axes, which were consistent with the orientation of Heschl's gyrus and with functional organization revealed by fMRI investigations. The frequency representation in the right hemisphere was approximately 5 mm anterior and approximately 7 mm lateral to that in the left hemisphere, corroborating with MEG measurements hemispheric asymmetries reported by cytoarchitectonic studies of the PAC and by MRI morphometry. In the left hemisphere, frequency gradients were inflected near 2 kHz in normal hearing subjects. These SSR frequency gradients were attenuated in both hemispheres in tinnitus subjects. Dipole power was also elevated in tinnitus, suggesting that more neurons were entrained synchronously by the AM envelope. These findings are consistent with animal experiments reporting altered tonotopy and changes in the response properties of auditory cortical neurons after hearing loss induced by noise exposure. Degraded frequency representations in tinnitus may reflect a loss of intracortical inhibition in deafferented frequency regions of the PAC after hearing injury.

Acoustic Stimulation↗
PubMed2005

Overloading temporal memory.

This study tested the hypothesis that memory is a major source of variance in temporal processing. Participants categorized intervals as short or long. The number of base durations and interval types mixed within blocks of trials varied from 1 session to another. Results revealed that mixing 2 base durations within blocks increased categorization errors, but mixing 2 marker types did not. Results are attributed to the involvement of more than 1 memory representation, which is argued to show the critical role of memory in temporal processing. Because mixing modalities has no such effect, it was argued that modalities share a common representation in memory. Finally, there was no difference in the perceived duration of auditory and visually marked intervals, which is inconsistent with most reports on this effect.

Adult↗
PubMed1991

Melodic, rhythmic, and timbral perception of adult cochlear implant users.

The purpose of this pilot study was to investigate adult Ineraid and Nucleus cochlear implant (CI) users' perceptual accuracy for melodic and rhythmic patterns, and quality ratings for different musical instruments. Subjects were 18 postlingually deafened adults with CI experience. Evaluative measures included the Primary Measures of Music Audiation (PMMA) and a Musical Instrument Quality Rating. Performance scores on the PMMA were correlated with speech perception measures, music background, and subject characteristics. Results demonstrated a broad range of perceptual accuracy and quality ratings across subjects. On these measures, performance for temporal contrasts was better than for melodic contrasts independent of CI device. Trends in the patterns of correlations between speech and music perception suggest that particular structural elements of music are differentially accessible to cochlear implant users. Additionally, notable qualitative differences for ratings of musical instruments were observed between Nucleus and Ineraid users.

Adult↗
PubMed1995

[Effect of contralateral noise exposure on otoacoustic distortion product emissions in man].

The influence of contralateral white noise with levels of 50 and 60 dBnHL on the amplitude of distortion-product otoacoustic emissions (DPOAE) was measured. Thirty ears of normally hearing adults (17 women, 13 men, mean age 26.5 +/- 5.3 years) were examined. Two representative DPOAE frequencies 2f1-f2 = 1342 Hz and 6341 Hz were compared. The lower DPOAE frequency was placed in the frequency region where middle-ear pressure has a strong influence on DPOAE amplitudes, the higher DPOAE frequency respectively in the region where lesser influence is exerted by middle-ear pressure. During the application of contralateral white noise a statistically significant total of 85% of DPOAE amplitudes was reduced, although there was some variation in the individual behaviour of DPOAE amplitudes. In general the higher DPOAE frequency (6341 Hz) was reduced distinctly less than the lower DPOAE frequency (1342 Hz). The reaction of DPOAE amplitude depended closely on the time course of the contralateral stimulus and amplitude reductions were present over 10 minutes without adaptation or fatigue. It is not possible to differentiate between middle-ear or inner-ear mediate effects but the middle ear is at least involved. Based on the presence of those DPOAE amplitude reductions over ten minutes without adaptation or fatigue and the fact that lower frequencies are influenced much more than higher frequencies a synergistic effect--middle-ear and efferent mediated--is suggested.

Adult↗
PubMed2004

Cochlear compression: effects of low-frequency biasing on quadratic distortion product otoacoustic emission.

Distortion product otoacoustic emissions (DPOAEs) are generated from the nonlinear transduction n cochlear outer hair cells. The transducer function demonstrating a compressive nonlinearity can be estimated from low-frequency modulation of DPOAEs. Experimental results from the gerbils showed that the magnitude of quadratic difference tone (QDT, f2-f1) was either enhanced or suppressed depending on the phase of the low-frequency bias tone. Within one period of the bias tone, QDT magnitudes exhibited two similar modulation patterns, each resembling the absolute value of the second derivative of the transducer function. In the time domain, the center notches of the modulation patterns occurred around the zero crossings of the bias pressure, whereas peaks corresponded to the increase or decrease in bias pressure. Evaluated with respect to the bias pressure, modulated QDT magnitude displayed a double-modulation pattern marked by a separation of the center notches. Loading/unloading of the cochlear transducer or rise/fall in bias pressure shifted the center notch to positive or negative sound pressures, indicating a mechanical hysteresis. These results suggest that QDT arises from the compression that coexists with the active hysteresis in cochlear transduction. Modulation of QDT magnitude reflects the dynamic regulation of cochlear transducer gain and compression.

Acoustic Stimulation↗
PubMed2006

Distortion product otoacoustic emission (DPOAE) in tinnitus patients.

The aim of this study was to determine the effect of tinnitus (experiment I) and the combined effect of tinnitus and sensorineural hearing loss (experiment II) on the distortion product otoacoustic emission (DPOAE) for two age groups of tinnitus patients. Tinnitus patients with normal earing, along with normal-hearing control subjects, participated in experiment I. They were divided into two age groups, below 50 and above 50 years. Experiment I showed that the DPOAE levels in the tinnitus patients were lower than those in the normal-hearing (nontinnitus) subjects. The differences depended on the frequency and the age of the patients, suggesting the confounding influence of presbyacusis. The second group of tinnitus patients with increasing and notch-like hearing loss participated in experiment II. They were also divided into two age groups, below 50 and above 50 years. The data from experiment II showed that DPOAE activity well reflects the increasing and notch-like hearing loss functions up to about 40 dB HL. The effect of age on the DPOAE level was clearly noted only for the tinnitus patients with clinically normal-hearing thresholds and was ambiguous for the tinnitus patients with hearing loss.

Adolescent↗