摘要:

A critical bibliography of published articles concerning the effects of noise exposure on hearing has been compiled for the NIH. The review concentrated on articles published over the last 14 years; however, historical highlights of the past 50 years or so were included for continuity. This paper attempts to summarize in tutorial fashion the results of that review with regard to auditory physiology in general and explores some of the current issues with specific reference to acoustic injury. To date, most of the effort toward understanding acoustic injury has been focused on the auditory periphery; the emphasis is clear simply from the number of papers published in that area. On the other hand, the response of the central nervous system to noise exposure or to any type of damage in the periphery is essentially unknown. It would seem that it is now time to assume a more balanced approach and recognize the importance of the CNS with regard to understanding the overall consequences of acoustic injury.

ISSN:0001-4966    

DOI:10.1121/1.391446

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The interaction of noise with a variety of other agents and with some physical characteristics of the individual to produce noise‐induced hearing loss is reviewed critically. The review is restricted, for the most part, to publications since 1970. Other agents interacting with steady‐state noise that are reviewed here include: (1) ototoxic drugs (kanamycin, neomycin, ethacrynic acid, furosemide, and salicylates), (2) impulse noise, and (3) whole‐body vibration. Physical characteristics of the individual that are reviewed are: (1) age, (2) presence of previous hearing loss from prior noise exposure, (3) eye color, and (4) race. Suggestions for future research in this general area are also made. Some of these suggestions are as follows: (1) to extend studies of the interaction of steady‐state noise with impulse noise, salicylates, and whole‐body vibration to encompass a broader range of exposure conditions, including exposure conditions typically encountered by the worker, (2) to develop an animal model of presbycusis to explore the interactions of noise‐induced hearing loss and presbycusis, and (3) to explore the potential interactions resulting from concurrent exposure to multiple agents, such as impulse noise and ototoxic drugs, in younger, more susceptible animals.

ISSN:0001-4966    

DOI:10.1121/1.391447

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Amino acid solutions have absorptions which are generally small compared to those for proteins. Proteolytic enzyme treatment of proteins in solution reduces their absorption. These observations suggest that absorption increases with molecular weight. However, measurements of sugars, polysaccharides, amino acids, and proteins yield no correlations of absorption with molecular weight within these groups. Therefore, it is concluded that absorption increases in these molecules with increasing molecular weight only in a threshold sense, with absorption increasing significantly only in a restricted molecular weight range. This range may approximate that observed for polyethylene glycol and dextran, viz., 1 to 100 monomer units. However, there is some indication that the transition range may be narrower than a factor of 100 in molecular weight.

ISSN:0001-4966    

DOI:10.1121/1.391448

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Measurements and theoretical calculations of timpani modal frequencies and decay times are made for the cases of no kettle enclosure and kettle enclosures of varying volume. For the calculations, the timpani membrane is assumed to be ideal and the kettle is assumed to be a rigid cylinder which is volume equivalent to the actual kettle. A Green function method is used for calculating the effects of air loading. The calculated modal frequencies and decay times are generally in good agreement with the experimental measurements. In particular, for typical kettle enclosures, the frequency ratiosf11 : f21 : f31 ; f41are found to be close to the harmonic ratios 2 : 3 : 4 : 5 over the normal playing range 100 Hz≲f11≲175 Hz.

ISSN:0001-4966    

DOI:10.1121/1.391449

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

We identified certain assumptions implicit in two divergent approaches to studying vocal affect signaling. The ‘‘covariance’’ model assumes that nonverbal cues function independently of verbal content, and that relevant acoustic parameters covary with the strength of the affect conveyed. The ‘‘configuration’’ model assumes that both verbal and nonverbal cues exhibit categorical linguistic structure, and that different affective messages are conveyed by different configurations of category variables. We tested these assumptions in a series of two judgment experiments in which subjects rated recorded utterances, written transcripts, and three different acoustically masked versions of the utterances. Comparison of the different conditions showed that voice quality andF0 level can convey affective information independently of the verbal context. However, judgments of the unaltered recordings also showed that intonational categories (contour types) conveyed affective information only in interaction with grammatical features of the text. It appears necessary to distinguish between linguistic features of intonation and other (paralinguistic) nonverbal cues and to design research methods appropriate to the type of cues under study.

ISSN:0001-4966    

DOI:10.1121/1.391450

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Performance on tests of pure‐tone thresholds, speech‐recognition thresholds, and speech‐recognition scores for the two ears of each subject were evaluated in two groups of adults with bilateral hearing losses. One group was composed of individuals fitted with binaural hearing aids, and the other group included persons with monaural hearing aids. Performance prior to the use of hearing aids was compared to performance after 4–5 years of hearing aid use in order to determine whether the unaided ear would show effects of auditory deprivation. There were no differences over time for pure‐tone thresholds or speech‐recognition thresholds for both ears of both groups. Nevertheless, the results revealed that the speech‐recognition difference scores of the binaurally fitted subjects remained stable over time whereas they increased for the monaurally fitted subjects. The findings reveal an auditory deprivation effect for the unfitted ears of the subjects with monaural hearing aids.

ISSN:0001-4966    

DOI:10.1121/1.391451

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

Thresholds for 2‐kHz sinusoidal signals were determined in the presence of a notched‐noise masker, for six normal‐hearing listeners and 12 listeners with cochlear hearing losses. Following Patterson and Nimmo Smith [J. Acoust. Soc. Am.67, 229–245 (1980)], conditions were used where the notch was placed both symmetrically and asymmetrically about the signal frequency. The auditory filter shape for both the low‐ and high‐frequency side of the filter was calculated using the rounded‐exponential form of the filter. In six hearing‐impaired listeners, the auditory filter shape showed a shallow low‐frequency skirt indicating pronounced susceptibility to the upward spread of masking. In two hearing‐impaired listeners, the filter shape showed a shallow high‐frequency skirt, indicating pronounced susceptibility to the downward spread of masking. Two other listeners with mild threshold losses had steeper and more symmetric filters than normal, suggesting either a small conductive loss or an attenuation factor of sensorineural origin not associated with a degradation of frequency resolution. In the remaining two listeners, the auditory filter had too little selectivity for its shape to be reliably determined.

ISSN:0001-4966    

DOI:10.1121/1.391452

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

These experiments were designed to assess the importance of different types of information which might be used in detecting intensity changes for pure tones. Thresholds for detecting an intensity change, expressed as 10 log (ΔI/I), were measured over a wide range of frequencies and levels under conditions where one or more sources of information was either present or was removed. Spread of excitation was restricted by using bandstop noise centered at the signal frequency. Information conveyed by dynamic responses to signal onsets and offsets was eliminated by masking onsets and offsets with bursts of bandpass noise. Phase‐locking information was eliminated by using high‐frequency signals (above 5 kHz). Dynamic responses to signal onsets and offsets appear to play little role in intensity discrimination. Phase locking does appear to be important since Weber’s law or a near‐miss to it was observed at low frequencies, whereas at high frequencies performance deteriorated at moderate sound levels, and improved again at high levels. A preliminary experiment, using 225‐ms stimuli revealed only a small midlevel deterioration at high frequencies. However, when 30‐ms stimuli were used a large deterioration was observed, performance being worse when bandstop noise was presented with the tone. Hence at short durations and high frequencies spread of excitation seems to be important: When it is restricted by bandstop noise values of 10 log (ΔI/I) observed at moderate levels it can be as large as 14 dB. The results of the experiments are consistent with a bimodal distribution of thresholds in primary auditory neurons; at intermediate levels neither population will operate effectively. The absence of a level effect at low frequencies can be explained by phase‐locking cues extending the range over which VIIIth‐nerve fibers can signal changes in intensity.

ISSN:0001-4966    

DOI:10.1121/1.391453

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The precedence effect, as investigated by Wallachetal. [Am. J. Psychol.62,324–336 (1949)] was studied in three experiments. Experiment I was a replication of the original work of Wallachetal. Although the first click pair appears to dominate the perception of the position of the lateral image, the effect of the first click pair does not appear to ‘‘offset’’ or ‘‘cancel’’ the effect of the second click pair in terms of producing a lateral image at midline. The data are consistent with Zurek’s [J. Acoust. Soc. Am.67,952–964 (1980)] proposal that the binaural system is less sensitive to the interaural temporal difference of the second click pair. Experiment II indicated that the effect of the first click pair on lateral judgments still dominates that of the second click pair when the images are judged to be off midline. In all of these studies, the variability of the data is quite high. Experiment III showed that the first click pair also led to a larger change in masked thresholds (masking‐level differences, MLDs) than does the second click pair. These data reconfirm the use of two‐click stimuli for demonstrations of the precedence effect and they describe some of the limitations of the procedure and the generalities of the effect.

ISSN:0001-4966    

DOI:10.1121/1.391454

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP

摘要:

The neotropical frogLeptodactylusalbilabrisexhibits the greatest sensitivity to substrate‐borne vibrations (seismic stimuli) reported to date for any terrestrial animal. Nerve fibers from the source of this extraordinary sensitivity in the ear show clear stimulus‐evoked modulations of their resting discharge rates in response to sinusoidal seismic stimuli with peak accelerations less than 0.001 cm/s2(10−6g). Evidence indicates that its source is the saccule, an organ of hearing in fish and of balance in man. We report that single vibration‐sensitive fibers in the white‐lipped frog saturate at (whole animal) displacements of 10 Å peak to peak [Fig. 1(b)]. Assuming a conservative 20‐dB dynamic range for these fibers, theinvivofrog saccule and the mammalian cochlea exhibit roughly equal sensitivities to displacement.

ISSN:0001-4966    

DOI:10.1121/1.391455

出版商:Acoustical Society of America    

年代:1984

数据来源: AIP