摘要:

It is found that methods commonly used in medicine for the evaluation of impairment to hearing and the relation of this impairment to noise exposure may lead to significant underestimates of the severity of noise‐induced hearing impairment and overestimations of tolerable limits for exposure to noise. Criteria of acceptable degrees of hearing impairment for speech and a criterion of an acceptable percentage of people to suffer noise‐induced impairment to hearing are suggested. Procedures are derived for calculating Speech Impairment Risk Percent (SIR) which represents damage effect on hearing of a wide variety of noise environments and which can be used for specifying noise exposure limits that would be rated as tolerable for the suggested, or for other, criteria. The proposed procedures appear to be valid, within the state of present knowledge, for daily continuous or intermittent exposures to steady‐state or impulsive noises.

ISSN:0001-4966    

DOI:10.1121/1.1913457

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Reactions offered here (a) urge rethinking on the adequacy of a widely used criterion for defining hearing handicap in view of data referenced in the subject report, (b) criticize the author's evaluations basic to estimating hearing loss risk from known levels of noise exposure and recommending safe limits for hearing, and (c) question the use of proposed complex schemes for rating noise hazards to hearing as derived from presumed relationships between temporary and permanent noise‐induced threshold shifts in hearing.

ISSN:0001-4966    

DOI:10.1121/1.1913458

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Dr. Kryter's arguments and proposals are good in principle but faulty in detail. Confusion could have been avoided by a clear separation of the concept ofimpairment(any change for the worse in structure or function) fromhandicap(a loss of efficiency in social communication). The AAOO rule deals with handicap, not impairment. Also its “high fence” recognizes that “everyday speech” is not only speech at 65 dB SPL but includes some speech that is much louder. The AAOO rule was deliberately simplified to promote its use. The “Social Adequacy Index for Hearing” of 1948 is valid in prinicple but is numerically inaccurate because of poor enunciation of the recorded test material that was employed. For predicting handicap in speech communication the hearing threshold level at 2000 Hz is critical. More studies of speech discrimination in subjects who have typical noise‐induced hearing loss involving this frequency are badly needed.

ISSN:0001-4966    

DOI:10.1121/1.1913459

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

National Institute for Occupational Safety and Health (NIOSH) statistics indicate that a 26‐dB fence of hearing impairment for comparing hearing levels averaged at 0.5, 1, and 2 kHz vs 1, 2, and 3 kHz yield essentially equal risk values for noise‐exposed populations at retirement age. On the other hand, Kryter, using a 16‐dB fence for the averaging at 0.5, 1, and 2 kHz, found risk values comparable to those found using a 26‐dB fence for the averaging at 1, 2, and 3 kHz. The data “baseline” inequality between the “non‐noise”‐exposed and noise‐exposed populations used by Kryter in the development of his SIR table raises questions as to the compatibility of his different populations. If indicated baseline corrections are used, Kryter'sriskvalues compare favorably with NIOSH data.

ISSN:0001-4966    

DOI:10.1121/1.1913460

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

The 55‐dBA8‐h basic damage‐risk criterion proposed by Kryter [J. Acoust. Soc. Am.53, 1211 (1973)] is held to be unrealistically overconservative because it is based on erroneous assumptions and extrapolations from data.

ISSN:0001-4966    

DOI:10.1121/1.1913461

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Critiques by A. Cohen, H. Davis, B. L. Lempert, and W. D. Ward of my paper “Impairment to Hearing from Exposure to Noise” are treated individually. Questions raised by the reviewers are discussed and areas for further discussion are noted.

ISSN:0001-4966    

DOI:10.1121/1.1913462

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

A form of geometrical acoustics approach to high‐frequency noise propagation in acoustically treated corridors is presented. Expressions are given for the attenuation of sound for a variety of cases when one or more walls have either high‐ or low‐absorption coefficients, for the transmission of sound through open doorways, and for noise propagation at corridor junctions and corners. Experimental confirmation of the predictions is given.

ISSN:0001-4966    

DOI:10.1121/1.1913463

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

A high‐intensity acoustic test facility was constructed at the Jet Propulsion Laboratory (JPL) to support the Mariner Mars 1971 project. For ease of construction, the reverberation chamber itself is rectangular, which resulted in very little sacrifice in acoustic performance. Levels as high as 156 dB can be achieved with the chamber empty and test levels of 150 dB have been used with a Mariner Mars spacecraft model (full size) in the chamber. Levels as high as this must be generated using electropneumatic transducers, which modulate gaseous nitrogen to this facility.

ISSN:0001-4966    

DOI:10.1121/1.1913464

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

This paper reports the results of some preliminary two‐interval roving‐level discrimination experiments designed to test certain predictions of the preliminary theory of intensity resolution presented in the first paper of this series [N. I. Durlach and L. D. Braida, J. Acoust. Soc. Am.46, 372–383 (1969)]. Discrimination performance was measured for roving‐level ranges in the interval 0 to 54 dB and intersignal durations in the interval 0 to 9 sec. Although the results, when averaged over levels, are roughly consistent with the theory, there is a substantial dependence of sensitivity on level that is inconsistent with the theory. Much of this dependence appears to be similar to that found previously in one‐interval experiments [L. D. Braida and N. I. Durlach, J. Acoust. Soc. Am.51, 483–502 (1972)], and to be interpretable in terms of deviations from Weber's law and the edge effect (caused by the use of the extreme intensities in the stimulus set as perceptual anchors).

ISSN:0001-4966    

DOI:10.1121/1.1913465

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP

摘要:

Theory and some empirical evidence would predict that humans should exhibit little ability to localize sounds underwater; however, other observations seemed to contradict this position. In order to provide relavant data on the issue, a pilot study was conducted; its results suggested that man can localize sounds underwater—at least to some degree. Accordingly, a major experiment was carried out utilizing 17 divers, who were free to move their heads but not their bodies, in an underwater localization task. In order to allow precision in the experiment, a Diver Auditory Localization System (DALS) was developed; its design is based on previous structures employed in underwater communication research and consists of an open polyvinyl choloride (VPC) framework to which five 3‐m arms and other equipment are attached. The five arms allowed placement—at ear level—of underwater projectors at angles (to the diver) of 0°, 45°, 90°, 270°, and 315°. Subjects responded to four different signals—250‐, 1000‐, and 6000‐Hz sinusoids and thermal noise—at 110 dB SPL (re0.0002 dyn/cm2); this level is approximately 40 dBreunderwater hearing thresholds. Responses to stimuli were accomplished by means of a specially constructed five‐position underwater switch coupled to an IBM key punch at the surface. The obtained scores were substantially above chance and demonstrate that humans are capable of at least some sound localization underwater.

ISSN:0001-4966    

DOI:10.1121/1.1913466

出版商:Acoustical Society of America    

年代:1973

数据来源: AIP