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Results for “Pitch Perception”

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At least 289 records · Page 16Linked to original sources
PubMedDate not supplied

Telephone listening ability for hearing-impaired individuals.

Forty-five subjects with bilateral sensorineural hearing losses were divided into three groups (N = 15/group) based on the audiometric configuration of their test ear. The subjects were evaluated in three listening conditions by assessing their word discrimination ability by presenting stimuli at 86 dB SPL (simulating the output of a standard telephone handset ) and most comfortable loudness (MCL) (simulating the output of a telephone amplifier handset ). The three listening conditions were TDH-39 earphone, unaided telephone, and aided telephone with their personal hearing aid acoustically coupled to a telephone handset . Results indicated that subjects with precipitous hearing losses had similar word discrimination scores for all three listening conditions at 86 dB SPL and MCL. Subjects with gradual slope or flat hearing losses had similar word discrimination scores with a TDH-39 earphone, unaided telephone, and their hearing aids acoustically coupled to a telephone handset at 86 dB SPL. The subjects with gradual slope or flat losses also had similar word discrimination scores across the listening modes at MCL, but they had better word discrimination scores in all listening modes when the word lists were presented at MCL compared with 86 dB SPL.

Hearing Aids↗
PubMedDate not supplied

The time course of the acoustic reflex.

The time course of the impedance changes caused by the contralateral acoustic reflex was investigated in five normal hearing, young adult subjects The acoustic reflex function was measured with equipment having a time constant of 15 milliseconds which permitted precise temporal measures. Temporal intervals from signal onset and termination to various portions of the acoustic reflex function were derived using an analysis procedure based on the slope function underlying the acoustic reflex response. These temporal intervals are related to physiological events underlying the acoustic reflex.

Acoustic Stimulation↗
PubMedDate not supplied

Selecting amplification characteristics for young hearing-impaired children.

The task of selecting the electroacoustic characteristics of hearing aids for young hearing-impaired children continues to challenge many clinical audiologists. The rationale for a theoretically based approach to this problem is presented. Additionally, issues related to the choice of an idealized speech spectrum for a theoretical selection model are considered in relation to the acoustic environment and auditory needs of young hearing-impaired children. Finally, the preliminary version of a computer assisted speech spectrum approach, which facilitates the initial selection of frequency/gain and frequency/SSPL characteristics is presented.

Child, Preschool↗
PubMed1987

Insertion gain repeatability versus loudspeaker location: you want me to put my loudspeaker where?

The traditional 0 degree (straight-ahead) location of the loudspeaker during insertion gain measurements is a poor choice, based on theoretical considerations, from the standpoint of measurement repeatability. In a series of experiments, we were able to demonstrate that a location 45 degrees to the side, or 45 degrees up and 45 degrees to the side, provided a much more repeatable measurement of basically the same insertion gain response.

Acoustics↗
PubMed1987

Clinical ear canal probe tube measurements.

This paper describes a variety of areas in which ear canal probe tube microphone measurements can be useful to the audiologist. Areas such as measurement of hearing aid insertion gain to match some predetermined target levels, output sound pressure level in the ear canal (real ear SSPL90), and assessment of FM systems and FM system-hearing aid combinations are discussed. In addition, some variables affecting the accuracy of these measurements and the reliability will be discussed.

Acoustics↗
PubMed2002

Interference effects and phase sensitivity in hearing.

This paper reviews interference effects in the auditory system, particularly effects occurring in the outer ear and the inner ear (cochlea). Sounds enter the ear canal both directly and after reflections from the pinna. This results in complex spectral patterns, which vary systematically with the direction of incidence of the sound source relative to the head. Evidence is described indicating that these spectral patterns are used in the localization of sounds in space. The cochlea behaves like a limited-resolution frequency analyser. When the components of a complex sound are closely spaced in frequency, they can interfere on the basilar membrane (BM) within the cochlea. Interference effects on the BM are complex, as they are influenced by a physiologically active mechanism which introduces strong nonlinearities, including level-dependent amplification. Interference effects on the BM play a role in many aspects of auditory perception, including the perception of consonance and dissonance, the perception of pitch, the perception of changes in phase, and the perception of timbre. Interference effects in the cochlea may also play a role in producing the spectral regularity observed in sounds reflected from the ear (otoacoustic emissions).

Animals↗
PubMed2006

Ghost stochastic resonance with distributed inputs in pulse-coupled electronic neurons.

We study experimentally the phenomenon of ghost stochastic resonance in pulse-coupled excitable systems, for input signals distributed among different elements. Specifically, two excitable electronic circuits are driven by different sinusoidal signals that produce periodic spikes at distinct frequencies. Their outputs are sent to a third circuit that processes these spiking signals and is additionally perturbed by noise. When the input signals are harmonics of a certain fundamental (that is not present in the inputs) the processing circuit exhibits, for an optimal amount of noise, a resonant response at the frequency of the missing fundamental (ghost frequency). In contrast with the standard case in which the signals being directly integrated are sinusoidal, this behavior relies here on a coincidence-detection mechanism. When the input signals are homogeneously shifted in frequency, the processing circuit responds with pulse packages composed of spikes at a frequency that depends linearly on the frequency shift. Expressions for the dependence of the package period and duration on the frequency shift and spike width, respectively, are obtained. These results provide an experimental verification of a recently proposed mechanism of binaural pitch perception.

Journal Article↗
PubMed2005

Accessing ampli-tonotopic organization of rat auditory cortex by microstimulation of cochlear nucleus.

Auditory brainstem implants (ABI) that electrically stimulate the surface of cochlear nucleus have been clinically used for the rehabilitation of deaf patients with bilateral vestibular schwannomas. The change of pitch perception with an active electrode location is not as clear in ABIs as in cochlear implants, a factor which might play a role in poorer speech performance in ABIs. The objective of present work was to develop an animal ABI model that could provide physiological data for future ABI development and optimization. The experimental system included a penetrating microelectrode array for microstimulation of the cochlear nucleus and a surface microelectrode array for mapping evoked potentials over the auditory cortex. We first obtained tone-evoked cortical activation patterns, which represented a place code of the frequency and intensity of test tones, i.e., the ampli-tonotopic organization, and compared the patterns with those evoked by cochlear nuclear microstimulation. Our experimental results demonstrated that microstimulation of both the dorsal and ventral cochlear nucleus (DCN and VCN) could access the cortical ampli-tonotopic organization as acoustic stimuli did. We also found that the cortical dynamic range was wider for the DCN than VCN stimulation and for the low-frequency than for the high-frequency pathway. The present results have great implications for improved ABI performance.

Action Potentials↗
PubMed1978

Frequency selectivity of the peripheral auditory analyzer studied using broad band noise.

The sharpness of the frequency tuning of single auditory nerve fibers was studied in the rat on the basis of responses to broad band noise. The cross-spectra between the sound stimulus and the sound-to-stimulus locked discharge rate were used as estimates of the transfer functions of the peripheral auditory analyzer. The sharpness of the tuning obtained in that way was measured as Q3dB and Q10dB. It was found that these Q-values decreased with increasing stimulus intensity but that the decrease was different when it was based on measurements at 3 dB points of the obtained transfer functions compared with measuring it at 10 dB points. The change in width was less for fibers with low CF. In all the fibers studied the frequency of maximal response (CF) decreased with increasing sound intensity. The implication of these findings for pitch perception and for noise induced hearing loss is discussed.

Acoustic Stimulation↗
PubMedDate not supplied

Intrinsic oscillations and discharge regularity of units in the dorsal cochlear nucleus (DCN) of the barbiturate anesthetized gerbil.

Spike discharge patterns showing intrinsic oscillations (IOs) have been reported in units in the dorsal cochlear nucleus (DCN) of the decerebrate cat. These oscillations are related to the regularity of a unit's discharge rate and may be important for pitch perception. A DCN unit's regularity can be affected by several factors including: synaptic architecture, cell membrane properties, and the auditory nerve discharge rate. Responses to multiple presentations of short-duration tone bursts (200 ms duration, 1 s trial) at the unit's best frequency (BF) at 20 dB re threshold were recorded from 297 units in the DCN of the barbiturate-anesthetized gerbil. Comparisons of unit regularity properties and IO properties are shown. The relative power spectrum (Fourier transform of the autocorrelogram normalized by the average rate) was used to quantify IO properties. Most units (84%) exhibited IOs in their sustained discharge rate. With the exception of Onset units and most bursting units, the mean inter-spike interval was correlated with the IO frequency and the coefficient of variation was correlated with the IO magnitude. These results suggest that stimulus-encoding mechanisms utilizing IOs may depend on the temporal evolution of the units' regularity properties.

Animals↗
PubMed2001

Evidence for a behavioral significance of saccular acoustic sensitivity in humans.

In this article the results are reported of an experiment to provide direct evidence for a perceptual and behavioral significance of human saccular acoustic sensitivity. Ten human subjects were stimulated monaurally with 100-ms trains of 10-ms tone pulses with pulse repetition rate of 40 Hz, and were required to rate the pleasantness of the stimuli on a nine-point scale. The design included three within-subject factors: carrier frequency (two levels, 200 and 4,000 Hz), intensity [13 levels from 55 to 115 dB(A) in 5-dB steps] and ear (left and right). For intensities above 90 dB myogenic vestibular evoked potentials (MVEP) were also obtained from the ipsilateral sternocleidomastoid muscle from which it was possible to obtain thresholds by linear regression of MVEP amplitudes against intensity. A further between-subjects factor was added which assessed subjects' attitude to vestibular sensations. The results indicate that across subjects there is a general trend of decreasing pleasantness with increasing intensity, but for the 200-Hz condition there is a significant positive departure from monotonicity in pleasantness (p<0.05) above the mean saccular threshold. However, when split by the between-subjects factor, the positive departure was only evident for those subjects who have a positive attitude to vestibular sensations (p < 0.01). Implications of these results for human responses to loud sound and the possible evolutionary significance of saccular acoustic sensitivity are discussed.

Attitude↗
PubMed2001

Intensity-invariance of fine time structure in basilar-membrane click responses: implications for cochlear mechanics.

Basilar-membrane and auditory-nerve responses to impulsive acoustic stimuli, whether measured directly in response to clicks or obtained indirectly using cross- or reverse-correlation and/or Fourier analysis, manifest a striking symmetry: near-invariance with stimulus intensity of the fine time structure of the response over almost the entire dynamic range of hearing. This paper explores the origin and implications of this symmetry for cochlear mechanics. Intensity-invariance is investigated by applying the EQ-NL theorem [de Boer, Aud. Neurosci. 3, 377-388 (1997)] to define a family of linear cochlear models in which the strength of the active force generators is controlled by a real-valued, intensity-dependent parameter, gamma (with 0 < or = gamma < or = 1). The invariance of fine time structure is conjectured to imply that as gamma is varied the poles of the admittance of the cochlear partition remain within relatively narrow bands of the complex plane oriented perpendicular to the real frequency axis. Physically, the conjecture implies that the local resonant frequencies of the cochlear partition are nearly independent of intensity. Cochlear-model responses, computed by extending the model obtained by solution of the inverse problem in squirrel monkey at low sound levels [Zweig, J. Acoust. Soc. Am. 89, 1229-1254 (1991)] with three different forms of the intensity dependence of the partition admittance, support the conjecture. Intensity-invariance of cochlear resonant frequencies is shown to be consistent with the well-known "half-octave shift," describing the shift with intensity in the peak (or best) frequency of the basilar-membrane frequency response. Shifts in best frequency do not arise locally, via changes in the underlying resonant frequencies of the partition, but globally through the intensity dependence of the driving pressure. Near-invariance of fine time structure places strong constraints on the mechanical effects of force generation by outer hair cells. In particular, the symmetry requires that the feedback forces generated by outer hair cells (OHCs) not significantly affect the natural resonant frequencies of the cochlear partition. These results contradict many, if not most, cochlear models, in which OHC forces produce significant changes in the reactance and resonant frequencies of the partition.

Acoustic Impedance Tests↗
PubMed2002

Temporal weighting in sound localization.

The dynamics of sound localization were studied using a free-field direct localization task (pointing to sound sources) and an observer-weighting analysis that assessed the relative influence of each click in a click-train stimulus. In agreement with previous studies of the precedence effect and binaural adaptation, weighting functions showed increased influence of the onset click when the interclick interval (ICI) was short (<5 ms). For longer ICIs, all clicks in a train contributed roughly the same amount to listeners' localization responses. Finally, when a short gap was introduced in the middle of a train, the influence of the click immediately following the gap increased, in agreement with the "restarting" results obtained by Hafter and Buell [J. Acoust. Soc. Am. 88, 806-812 (1990)].

Acoustic Stimulation↗
PubMed2003

Basilar-membrane responses to multicomponent (Schroeder-phase) signals: understanding intensity effects.

Harmonic complexes comprised of the same spectral components in either positive-Schroeder (+Schr) or negative-Schroeder (-Schr) phase [see Schroeder, IEEE Trans. Inf. Theory 16, 85-89 (1970)] have identical long-term spectra and similar waveform envelopes. However, localized patterns of basilar-membrane (BM) excitation can be quite different in response to these two stimuli. Measurements in chinchillas showed more modulated (peakier) BM excitation for +Schr than -Schr complexes [Recio and Rhode, J. Acoust. Soc. Am. 108, 2281-2298 (2000)]. In the current study, laser velocimetry was used to examine BM responses at a location tuned to approximately 17 kHz in the basal turn of the guinea-pig cochlea, for +Schr and -Schr complexes with a 203-Hz fundamental frequency and including 101 equal-amplitude components from 2031 to 22,344 Hz. At 35-dB SPL, +Schr response waveforms showed greater amplitude modulation than -Schr responses. With increasing stimulation level, internal modulation decreased for both complexes. To understand the observed phenomena quantitatively, responses were predicted on the basis of a linearized model of the cochlea. Prediction was based on an "indirect impulse response" measured in the same animal. Response waveforms for Schroeder-phase signals were accurately predicted, provided that the level of the indirect impulse used in prediction closely matched the level of the Schroeder-phase stimulus. This result confirms that the underlying model, which originally was developed for noise stimuli, is valid for stimuli that produce completely different response waveforms. Moreover, it justifies explanation of cochlear filtering (i.e., differential treatment of different frequencies) in terms of a linear system.

Animals↗
PubMed2004

The psychomechanics of simulated sound sources: material properties of impacted bars.

Sound can convey information about the materials composing an object that are often not directly available to the visual system. Material and geometric properties of synthesized impacted bars with a tube resonator were varied, their perceptual structure was inferred from multidimensional scaling of dissimilarity judgments, and the psychophysical relations between the two were quantified. Constant cross-section bars varying in mass density and viscoelastic damping coefficient were synthesized with a physical model in experiment 1. A two-dimensional perceptual space resulted, and the dimensions were correlated with the mechanical parameters after applying a power-law transformation. Variable cross-section bars varying in length and viscoelastic damping coefficient were synthesized in experiment 2 with two sets of lengths creating high- and low-pitched bars. In the low-pitched bars, there was a coupling between the bar and the resonator that modified the decay characteristics. Perceptual dimensions again corresponded to the mechanical parameters. A set of potential temporal, spectral, and spectrotemporal correlates of the auditory representation were derived from the signal. The dimensions related to mass density and bar length were correlated with the frequency of the lowest partial and are related to pitch perception. The correlate most likely to represent the viscoelastic damping coefficient across all three stimulus sets is a linear combination of a decay constant derived from the temporal envelope and the spectral center of gravity derived from a cochlear representation of the signal. These results attest to the perceptual salience of energy-loss phenomena in sound source behavior.

Adult↗