PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Psychoacoustics”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMedDate not supplied

A multivariate strategy for prediction of psychoacoustic performance from electroacoustic characteristics of hearing aids.

Sentence length psychoacoustic material was processed through 16 hearing aids and presented to 220 listeners. Twenty-nine indices of electroacoustic performance were abstracted from a testing program under laboratory conditions. Through a multivariate statistical strategy, psychoacoustic achievement was shown to be positively correlated to and could be predicted by a knowledge of white noise gain, bandwidth below and above 1 kHz, frequency response regularity, and transiet distortion (multiple R = 0.77; F = 2.04; df = 5,10). It was concluded that a multivariate statistical tactic, when used with discretion, can be a useful and powerful tool to predict psychoacoustic performance from a knowledge of hearing aid electroacoustic characteristics.

Amplifiers, Electronic↗
PubMed1979

Automatic speech recognition using psychoacoustic models.

An approach to automatic speech recognition is described, which, in a straightforward way, follows the concept of (1) preprocessing in terms of auditory parameters and (2) subsequent classification and recognition. The preprocessing system has been realized in analog hardware, while recognition is carried out on a digital computer. In the preprocessing system, the essential psychoacoustic principles of the perception of loudness, pitch, roughness, and subjective duration are implemented with some approximation. The system essentially consists of 24 bandpass filters, nonlinear transformation of each filter output into specific loudness and specific roughness, and final transformation of these parameters into total loudness, total roughness, and three spectral momenta. As a means to further reduce the information flow, continuous selection of dominant parameters is also considered on the basis of psychoacoustic data. The subsequent recognition process is mainly characterized by (1) discrimination between speech and silent periods, (2) detection of syllable peaks and classification of syllable nuclei, and (3) assumption of syllable boundaries and classification of consonant clusters. Though the entire system as yet is far from being complete and perfect, the present results indicate that the concept provides a systematic and promising way towards automatic recognition of continuous speech.

Computers↗
PubMed1977

Comparative psychoacoustics: perspectives of peripheral sound analysis in mammals.

Psychophysical data on hearing in mammals are summarized. The data are then correlated to the anatomy and physiology of the ear. Common mechanisms of sound transfer and analysis in the acoustic system, with stress on the auditory periphery, are discussed. In this paper an attempt is made to bring basic psychoacoustic data from man and mammals in a logical line with the anatomy, physiology, and biophysics of the ear. This comparative approach is based on man and those five mammals, including bat and dolphin, for which sufficient data are available.

Animals↗
PubMedDate not supplied

Psychoacoustical tuning curves in audiology.

The correlation between classic masking patterns and psychoacoustical tuning curves is discussed quantitatively. A simplified method to measure such tuning curves in clinical use is described. They are shown to be insensitive to the frequency dependence of the hearing loss. Tuning curve data of six different groups including normal and hard-or-hearing observers are given: normal hearing, conductive hearing loss, degenerative hearing loss, noise-induced hearing loss, otosclerosis and Menière's disease. The resulting tuning curve data indicate that the frequency resolving power of the four groups mentioned last is greatley reduced but not completely absent, especially in the range of greater hearing loss. The correspondence between the frequency-resolving power measured by the tuning curve method and the result of speech discrimination tests is demonstrated. The measured data indicate that more than 50% of the patients with otosclerosis show reduced frequency selectivity although otosclerosis is commonly regarded as a conductive hearing loss.

Acoustic Stimulation↗
PubMed1977

[Determination of the impaired ear's frequency selectivity using psychoacoustical tuning curves (author's transl)].

An apparatus for clinical use is described by which simplified psychoacoustical tuning curves can be measured near 500 Hz and near 4 kHz. Data produced by four groups (normal hearing, conductive hearing loss, noise induced hearing loss and degenerative hearing loss) are separately averaged and compared. The first mentioned two groups as well as the third in the low frequency range show good frequency resolution, the others, however, show largely decreased frequency resolution.

Audiometry↗
PubMedDate not supplied

Psychoacoustic evaluation of present prostheses.

A battery of psychoacoustic tests, designed to specify auditory discriminations possible with present, single-channel auditory prostheses, was administered successfully to 12 of the 13 subjects. While no subject was able to perform all discriminations required by this battery of tests, there was no discrimination that at least one subject did not perform successfully. The typical subject could 1) discriminate intensity differences within normal limits for frequencies below 1000 Hz; 2) discriminate frequency differences quite normally at 125 and 250 Hz, but not at all at 1000 or 2000 Hz; 3) discriminate differences in signal duration, temporal patterning (rhythm), and spectrum (e.g., tone vs narrow-band noise); and 4) discriminate between pairs of synthesized vowel-like sounds. The results of masking experiments could only be interpreted in terms of intensity discrimination. Several subjects were able to relate stimulus intensity to loudness for low-frequency sounds; and they could relate stimulus frequency to pitch for signals below 25 Hz. The intelligibility of the subjects' speech was found to improve when their prostheses were activated.

Auditory Threshold↗
PubMed1978

Psychoacoustical aspects of synthesized vertical locale cues.

A new method of studying vertical localization is described whereby the high-frequency response of the external ear is synthesized by a computer program incorporating two variable latency delay and add processes. The resulting sounds were evaluated by presentation to subjects via headphones which bypass the external ear. Vertical movement of the sound source was perceived when the latency of one echo was changed dynamically between 100 and 300 microsecond and this effect required the presence of high-frequency signal components (about around 4 kHz). In further experiments, the variation of perceived elevation with echo delay was measured, and it is shown that the vertical locale of the apparent source is a monotonic function of echo latency in the 160-260 microsecond region. It is proposed that locale is decoded by a form of spectral pattern recognition, whereby the locale of the source is represented as a peak on an autocorrelation function. The time-axis values (between 160 and 260 microsecond) corresponding to these peaks are considered to correspond to vertical locale for elevations between roughly, 60 degrees above horizontal and 40 degree below.

Auditory Perception↗
PubMedDate not supplied

Filter effect of earmold venting: comparison of electroacoustic and psychoacoustic methods of evaluation.

The filter effect of venting an earmold was evaluated by measuring the coupler-acoustic and threshold responses to open versus closed earmolds. In the coupler-acoustic technique the effect of venting was determined by measuring the output of the experimental earmolds seated on a modified 2-cc coupler with a specified signal impressed upon the earphone. The real ear threshold technique called for the determination of threshold by five listeners for the same earphone-earmold system. The data indicated that the difference between the coupler and threshold measures were of the same order of magnitude as the difference seen by other investigators reporting coupler and real ear-probe tube microphone measures. It was concluded that the threshold technique provides the same general description of the effects of venting an earmold as does the probe tube technique and should thus provide a useful method for determination of the filter effects produced by the venting of an earmold.

Auditory Threshold↗
PubMedDate not supplied

Problems with earphone calibration using a manikin.

The response of a single TDH-39 receiver mounted in a MX-41/AR and an Auraldome cushion was measured psychoacoustically and electroacoustically using standard couplers and the Zwislocki coupler mounted in KEMAR (Knowles Electronic Manikin for Acoustic Research). Although the psychoacoustic data were similar for both cushions, electroacoustic responses differed across cushions and across couplers. It was concluded that an accurate method for evaluating circumaural earphones has not yet been developed and the manikin, in its present form, is unsuitable for supra-aural or circumaural earphone calibration.

Acoustics↗
PubMed1979

A model describing nonlinearities in hearing by active processes with saturation at 40 dB.

Data from literature related to nonlinearities of the peripheral part of the hearing system are collected and extended by results from measurements of acoustical responses, masking, cubic difference tones and Zwicker tones. The data indicate 40 dB as a significant value for the dynamic range in neurophysiology as well as for the sensation level in psychoacoustics dividing the total level range into two areas of different characteristics. A preliminary model assuming that the outer hair cells act as an amplifier which contains saturation (corresponding to 40 dB) and feed back to sensitize the inner hair cells is used to describe the measured effects at least qualitatively.

Auditory Fatigue↗
PubMed1977

An acoustic-perceptual method for the quantitative evaluation of hypernasality.

A computer implementation is proposed as a method for assessing the quality of an individual's speech from a perceptual and communicative point of view. The input to this procedure is a standardized set of speech samples (vowels and selected consonants) designed to permit an evaluation of the speaker's phonology. The output is a numerical specification of the functional adequacy of the target values of the phonetic segments under analysis. The computer program consists of three parts: a simulated auditory analyzer, the output of which is a spectral representation of each test item; an algorithm that computes a psychoacoustically based measure of distinctiveness or perceptual distance for each pair of test spectra, and a routine for comparing, in terms of this measure, the test items with the corresponding reference items drawn from a population of normal speakers or a recording made before patient intervention.

Acoustics↗
PubMed1977

[Results of the SISI test and Békésy audiometry in pseudohypacusis (author's transl)].

The terminology of pseudohypacusis is used for the syndrome of gaps between possible audiometric response and performance in testing. No etiology in psychological terms is defined for pseudohypacusis, although monetary compensation has been considered as a possible factor. SISI ratings of 0% in most instances (ranging to a maximum of 25%) have been observed. Békésy-audiometry produced Types I, II, IV and V tracings as well as unclassified curves, although the type V tracing is most commonly found. Results of fixed frequency Békésy-audiometry have also shown a shift of curves for continuous and interrupted tones (called "Type VI"). In some cases Type V and Type VI tracings were found in the same ears. The causes and psychoacoustic phenomenon involved remain unexplained.

Audiometry↗
PubMed1978

Clinical rationale for using an overhead speaker in evaluation of hearing aids.

A variable that has received little attention in the psychoacoustic evaluation of the hearing aid is the position of loudspeakers with respect to the listener, particularly the azimuth of the loudspeaker, which is used for presenting the competing message. In the past, a variety of locations have been used, some of which can bias the outcome of the evaluation. For this reason, this article suggests the use of an overhead speaker to deliver the competing signal. The overhead placement provides a neutral location that is highly desirable for making reliable repeated speech performance comparisons. In addition, the overhead speaker can be easily adapted to the testing environment while it produces the effect of surrounding the listener with the competing signal.

Amplifiers, Electronic↗
PubMed1979

[Physiological basis for a cochlear prosthesis (author's transl)].

For the attempt to develop a cochlear prosthesis, which allows some understanding of speech, it seems--at least for the first attempts--to be appropriate to mimic natural conditions as far as possible. The auditory nerve contains about 30,000 afferent fibres. Qualitatively, their behavior is similar but quantitative measures show considerably differences (2.3). Nothing certain can be said at present however about the spiral fibres originating from the outer hair cells. The quantitative differences between single afferents concern tuning, frequency selectivity, thresholds, intensity functions and--of particular interest for electrical stimulation--differences in timing of the activity pattern, brought about by differences in travelling time along the cochlear duct (2.3). The time differences seen in the activity pattern of different fibres are in the order of several ms (2.3.6;2.3.7). Actionpotentials elicited by natural acoustic stimuli show probabilistic behavior, that is they are not strictly determined. It is obvious that with artificial electrical stimulation not every surviving single fibre can be selectively stimulated. An electrode will always stimulate a group of fibres simultaneously. With any conceivable electrical stimulation all fibres in the suprathreshold region of the electrode will be synchronously activated (3.2); a fundamental difference to the natural situation. To estimate the number of channels, necessary to stimulate the auditory nerve with sufficient accuracy to allow speech perception we consider some psychoacoustic data. These have shown that the auditory system possesses the ability to differentiate a great number of different pitches, but on the other hand it is capable of integrating different frequency areas to a so called critical bandwidth. Sound energy falling into one critical bandwidth is integrated to a uniform auditory sensation. If one is to integrate various fibres of the auditory nerve to one channel of stimulation it seems to be adequate to use the critical bandwidth as a measure (3.1). According to this criterion 15 channels would have to be introduced into the speech region of the cochlea. This would allow 1.2 mm of cochlear length for each channel. Perfect electrical separation of the channels is required. Considering the severe distortions in neuronal activity pattern, introduced by electrical stimulation in comparison to the natural conditions it is not clear even whether the number given would be sufficient. On the other hand, current spreading would appear to prohibit any higher electrode density. As far as coding of sound parameters within one channel is concerned it is proposed that full use should be made of frequency analysis according to the place principle. In respect to coding of periodicity and loudness it is proposed to approach natural conditions as far as possible (3.3). Here delay times between the individual channels and a probabilistic character of the stimuli should be introduced to avoid dominance of periodicity pitch...

Action Potentials↗