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May 1988

Volume 83, Issue S1, pp. S1-S122

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back to top Session ZZ. Psychological Acoustics VI, Physiological IV, and Noise VI: Effect of Noise on the Auditory System
Contributed Papers
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Objective measures of the annoyance due to automobile passenger compartment noise (A)

John S. Lamancusa

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S114-S114 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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The annoyance attributable to complex noises consisting of multiple pure tones (which may or may not be harmonically related) and substantial broadband noise is not easily quantifiable. It has been shown that dBA is a poor indicator of loudness [Hellman and Zwicker, J. Acoust. Soc. Am. 82, 1700–1705 (1987)], and a number of other measures have been proposed. In this study, the results of subjective preference tests of passenger compartment noise are compared to objective measures of loudness and annoyance. Eight synthesized variations of the noise experienced at full throttle acceleration were ranked by 40 subjects according to their desirability. All samples were normalized to 101‐dB linear. These results are compared to the objective rating methods: AI (articulation index), ISO 532B (Zwicker method), Stevens Mark VII, CRP (Composite Rating of Preference), and PNL (perceived noise level). The CRP offers the best correlation with subjective results. The results of Mark VII, and ISO 532B are markedly improved by the addition of empirically derived corrections.
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Advanced turboprop aircraft flyover noise: Annoyance to counter‐rotating‐propeller configurations (A)

David A. McCurdy

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S114-S114 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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Two experiments were conducted to quantify the annoyance of people to the flyover noise of advanced turboprop aircraft with counter‐rotating propellers (CRP). The objectives were: (1) determine the effects of tonal content on annoyance; and (2) compare annoyance to advanced turboprop aircraft with annoyance to conventional turboprop and jet aircraft. A computer system was used to synthesize realistic, time‐varying simulations of advanced turboprop takeoff noise. For the first and second experiments, respectively, the system generated 27 noises representing CRP configurations with an equal number of blades on each rotor, and 35 noises representing CRP configurations with an unequal number of blades on each rotor. Included in each experiment were five conventional turboprop and five conventional jet takeoffs. Each noise was presented at three levels to subjects who judged the annoyance of each stimulus. Analyses of the judgments examine the effects on annoyance of blade passage frequency, tone‐to‐broadband noise ratio, and aircraft type. The annoyance prediction ability of current noise metrics is also examined.
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Quality assurance in automated monitoring of high‐energy impulsive sounds (A)

George A. Luz, William A. Russell, and Nelson D. Lewis

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S114-S114 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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U.S. Army policy is to measure noise levels whenever the projections of noise contouring computer programs show a noise environment “unacceptable” for residential use extending beyond the Federal installation's boundary. The threshold for “unacceptable” is an A‐weighted day‐night level (DNL) of 75 dB for aircraft and a C‐weighted DNL of 70 dB for high‐energy impulsive sounds. For adequate quality assurance (QA) in monitoring high‐energy impulsive sounds, statistical decision criteria are employed including threshold, duration, number of events per unit time, peak‐to‐SEL differences, and event probability distributions. The strengths and weaknesses of each QA criterion is discussed.
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Annoyance factors for common neighborhood noise (A)

Lynn S. Alvord

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S114-S115 (1988); (2 pages)

Online Publication Date: 13 Aug 2005

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Neighborhood noise is treated separately from aircraft or traffic noise in most local noise ordinances. Annoyance factors for common neighborhood noise were rated by 63 subjects in Salt Lake City, Utah. Subjects were asked to rate on a scale of 1 to 5, the degree to which each factor contributed to total annoyance. Most frequently mentioned annoying noise sources were dogs (38.1%), followed by sirens (12.7%). The following sources were also identified at higher than 3% incidence: garbage trucks, buses, children playing, doors slamming, noisy neighbors, helicopters, and metal stairways. Highest‐rated annoyance factors were: loudness, time of occurrence, frequency of occurrence, sound quality, and interference with sleep. Relative importance of annoyance factors found in this study differ from those of previous studies, which dealt more with aircraft or traffic noise. Fear and interference with conversation and sleep are of less importance for “neighborhood” noise than aircraft and traffic noise [T. J. Schultz, J. Acoust. Soc. Am. 64, 377–405 (1978)]. For neighborhood noise “meaning” the sound portrays is an important factor in certain situations. The importance of “situational factors” found here emphasizes the need for increased use of specific prohibitions in local noise ordinances.
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An overview of occupational noise regulations in Canada (A)

Deirdre A. Benwell

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S115-S115 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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In Canada, there are occupational noise regulations at both provincial and federal levels of government. An overview of present Canadian occupational noise legislation is given. In addition, recent Canadian activities concerning occupational noise exposure standards, guidelines, and other important background documents are described. The various methods used to assess compensation for occupational hearing loss are also summarized. Some recommendations are made for future activities in this area.
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The critical exposure in acoustic trauma (A)

W. Dixon Ward

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S115-S115 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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As one increases the intensity I of a noise exposure of fixed duration t, the resulting damage grows gradually up to a critical point at which the damage increases precipitously. The intensity at which this occurs, however, is not independent of the duration, so it cannot be called a “critical intensity.” Neither is this point dependent only on the total energy of the exposure It: Less energy is required at shorter durations in order to reach the critical point, so even “critical energy” would be a misnomer. Instead, the implication of an extended series of experiments in which chinchillas were given single exposures of a few minutes to 1.5 days at levels up to 120 dB SPL is that the critical exposure appears to be defined by I2t = C, or equivalently, p4t = k, where k is about 1010 Pa4 s for the chinchilla. This value is in agreement with recent results defining critical exposures to impulse noise in the chinchilla reported by Patterson and Hamernik [J. Acoust. Soc. Am. 81, 1118–1129 (1987)]. The meager data in the literature suggest that for man, k may be around 1010 Pa4 s. [Work supported by NINCDS Grant 12125.]
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Influences of temporal spacing of impulse noise on temporary and permanent threshold shifts (A)

Richard W. Danielson, Donald Henderson, and Samuel S. Saunders

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S115-S115 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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Chinchillas were exposed to impulse noise conditions with equal acoustic energy and spectra but with three different temporal patterns and two different amplitude levels (135 and 150 dB SPL, counterbalanced by 15‐dB trade‐offs in number of events). Auditory‐evoked responses were used to measure TTS and PTS. Degree of hearing loss and pattern of recovery were not uniform among the groups, contrary to assumptions related to the equal energy hypothesis. Relative to hearing loss after exposure to one impulse/second: (1) less hearing loss was seen after exposures to bursts of 1 impulse/50 ms and (2) greater hearing loss was seen when high‐level impulses occurred in salvos (pairs of impulses presented at 1‐s intervals, with 50‐ms interpulse interval in each pair). Findings will be compared to reports of a possible “period of vulnerability,” during which hearing loss may be more extreme if the ear is exposed to additional impulse noise while the ear is still recovering. [Work supported by NIOSH and the Department of the Army.]
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Altered susceptibility of the inner ear following repeated noise exposure (A)

Daniel J. Franklin, Barden B. Stagner, Brenda L. Lonsbury‐Martin, and Glen K. Martin

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S115-S115 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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The susceptibility of the inner ear to repeated noise exposure was investigated in the rabbit using tests of behavioral thresholds and distortion‐product emissions (DPEs). Behavioral thresholds, measured by a classical‐conditioning technique, were collected at 11 frequencies representative of the rabbit hearing range. Acoustic distortion products at the 2f1 − f2 frequency were measured as both DPE audiograms, generated by equilevel primaries at 45, 55, and 65 dB SPL, and input‐output functions in 5‐dB steps at nine frequencies. Following acquisition of control measures of DPEs and behavioral thresholds, DPEs were analyzed at regular intervals during both exposure and recovery periods and compared to corresponding behavioral measures. In four animals, following repeated episodes of exposure (octave band of noise centered at 1 kHz at 95 dB SPL) and recovery (3 weeks), both DPE amplitudes and behavioral audiograms revealed an increasing resistance to the effects of noise exposure. Comparison with the amount of amplitude reduction in a 4‐kHz DP caused by a 5‐min exposure during the preexposure periods to a 95‐dB SPL tone at 4.215 kHz (1/2 octave below the geometric mean of the primaries) showed a poor correlation with the lessened susceptibility to repeated noise exposure. The concept describing a dynamic mechanism of repair of sensory elements proposed by a number of investigators to explain recovery from sound exposure may account for the increasing resistance to the effects of repeated noise exposure as detected by both DPEs and behavioral responses. [Work supported by NINCDS.]
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Intracochlear pressures resulting from brief high intensity stimuli (A)

James H. Patterson, Jr., Ben T. Mozo, Karl Buck, and Laurent Decory

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S115-S116 (1988); (2 pages)

Online Publication Date: 13 Aug 2005

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A previous study has shown similar hearing loss and cochlear injury from exposures to impulses differing in peak pressure, but having the same energy and Fourier pressure spectrum. Nonlinear processes in the middle ear or transmission through the external and middle ear may render different stimuli more similar once they reach the cochlea, thus accounting for the equivalent injury observed. In order to explore this possibility, pressures in the basal turn of the cochleas of eight anesthetized chinchillas were measured for impulses presented at levels between 88‐and 147‐dB peak. This included the impulses used in the previous injury study. While nonlinearities were noted at the higher intensities, there was a remarkable preservation of the pressure‐time histories. In addition to these impulse stimuli, intracochlear pressures were measured using brief tone pips whose envelope was Gaussian. Frequencies of 700, 1375, 2000, 2700, and 4100 Hz were chosen to span the frequency response of the speaker. With these stimuli, nonlinearities appeared as both harmonic and subharmonic distortion as the intensities increased.
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Changes in frequency selectivity in the chinchilla following a noise induced permanent threshold shift (A)

Robert I. Davis, William A. Ahroon, and Roger P. Hammernik

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S116-S116 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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Evoked‐potential tuning curves (TC) were obtained on 106 chinchillas before and after acoustic overstimulation in order to assess the effects of the magnitude of hearing loss on frequency selectivity. Pre‐ and postexposure measures of auditory thresholds and masked thresholds (simultaneous tone‐on‐tone paradigm) were obtained in each animal at 0.5, 1, 2, 4, 8, and 11.2 kHz, using the evoked auditory response recorded from the inferior colliculus. Three TC variables (Q‐10 dB, tail‐tip difference, and the high‐frequency slope) and sensory cell losses were compared to the amount of noise‐induced permanent threshold shift (PTS) produced by a variety of noise exposures. Based upon large sample averages, frequencies showing PTS⩾20 dB also showed statistically significant differences between pre‐ and postexposure measures of all three TC variables. For 10 < PTS < 20 dB only the tail‐tip difference showed a statistically significant change, while for PTS ⩽ 10 dB there were no measurable changes in the TC variables. The percentage of outer hair cell loss showed an orderly and systematic increase as PTS increased and as TC variables changed across the entire range of test frequencies. The inner hair cells were essentially unaffected. These results show that there is a systematic change in the TC variables that define the quality of tuning as hearing loss progressively increases and that these changes are clearly related to outer hair cell losses. [Research supported by NIOSH and DOD.]
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“Enhanced” evoked response amplitudes in the chinchilla following acoustic trauma (A)

R. Salvi, S. Saunders, N. Powers, and M. A. Gratton

J. Acoust. Soc. Am. Volume 83, Issue S1, pp. S116-S116 (1988); (1 page)

Online Publication Date: 13 Aug 2005

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The amplitudes of auditory‐evoked responses recorded from chronic electrodes in the inferior colliculus of the chinchilla were measured before and after acoustic trauma. Acoustic trauma was induced using a 2‐kHz continuous tone that resulted in either 30–40 dB of TTS or PTS between 2–8 kHz. The high‐intensity exposures resulted in systematic changes in the input/output functions of the evoked response. The most striking change was an increase in the maximum amplitude (“enhanced”) of the evoked response at frequencies below and at the low‐frequency edge of the hearing loss (0.5 and 2 kHz). By contrast, the maximum amplitude seen at frequencies near the middle of the hearing loss or its high‐frequency border (4 and 8 kHz) was generally depressed. In addition to the change in maximum amplitude, there were also changes in the slope of the evoked response input/output functions. The results will be related to the pattern of hair cell loss as well as to possible underlying neural mechanisms. [Work supported by NIH R01 NS16761 and NS23894.]
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