Auditory Hazard Assessment Algorithm for Humans (AHAAH)

Executive Summary of the Development and Validation of AHAAH

G. Richard Price
U.S. Army Research Laboratory,
Human Research and Engineering Directorate
Aberdeen Proving Ground, Maryland 21005-5425

A bit of history. During the 1960s, the Army’s Human Engineering Laboratory had developed MIL STD-1474 as a design standard for the noise of Army materiel. In the early 1970s the Army’s Surgeon General adopted it as health hazard criterion (in the absence of another alternative). It was empirically based, and by the early 1980s, it was apparent that it did not assess the hazard from large caliber weapons properly.

Basic research on the mechanisms operative in intense noise exposures had also begun in the 1960s at the Human Engineering Laboratory. By the 1980s enough work had been done to establish the requirement for and to support the development of a mathematical model of the human ear’s response to intense sound.

Premises in the development of the model:

The primary site of loss is the Organ of Corti, the first site of injury probably being the tip links in the hair bundles on the outer hair cells.
At very high sound pressures (above 130 dB or so, depending on frequency) the loss process becomes fundamentally mechanical in nature and produces damage very rapidly (damage becomes linear in time).
The conductive path is itself resistant to changes; however, by shaping the flow of energy into the cochlea, it plays a major role in hearing loss. It exerts three types of influence.
1. It conducts best in the mid-range of frequencies, attenuating high and low frequencies.
2. The middle ear muscles can contract and attenuate transmission.
3. The annular ligament of the stapes limits middle ear displacements and at very high intensities imposes a peak-clipping non-linearity on the transmission path.
Mammalian cochleas are highly similar; thus the loss processes that operate in one species are likely to operate in another.

Research Strategy

We first sought to establish the loss processes operating at the level of the cochlea. This required noise exposures in experiments with biological ears that produced real losses in hearing. The cat was the animal model for this experimental work, chosen because of its similarity to the human ear as well as the amount that was already known about it.

Because middle ear muscle contractions affect the conductive path, their effects change the energy arriving at the cochlea and confound any effects seen. Anesthetized preparations were used in order to eliminate the confounding influence of middle ear muscle activity.

The conductive path, linear at reasonable intensities (below 130 dB or so), becomes highly non-linear at the intensities found in impulse noise fields around weapons. The basis for this non-linearity is the annular ligament of the stapes, which imposes a limit on displacement of about 20 microns (in cat). By not allowing displacements of 1000 to 2000 microns (if the middle ear were linear at all intensities), the middle ear becomes a peak-clipping device. To focus research on events in the cochlea, exposures need to be chosen to either avoid or to account for this phenomenon.

A Model Required!

In order to predict the complex interactions of the outer, middle, and inner ears just outlined and to provide insight in designing experiments, an electro-acoustic model of the ear was developed. The model was developed to conform with the structure of the ear. It could have been simpler, but the goal of modeling is insight. A solid theoretical base, coupled with the restraint imposed by the known anatomical structure of the ear kept the model properly formed and focused.

Many elements of the model had already been developed by others and had appeared in the literature. However, no one had put all the elements together or focused on predicting the effect of intense sounds on the ear. When connected, the conductive path matched closely the measured transfer functions for the external and middle ears. Additional elements had to be created to allow the analysis of the effect of intense sounds on the ear. These included modeling changes in the flow of energy in the conductive path at high intensities as well as the algorithm for calculating loss within the cochlea. The loss calculation was made at 23 locations evenly spaced along the basilar membrane (roughly 1/3 octave apart). At each location, the upward flexes of the basilar membrane were tracked (upward flex puts the sensitive elements in tension — a common mode for tissue failure), their amplitude in microns was squared and the sum maintained for each location. The units are called auditory hazard units (AHUs).

Development of the model proceeded in parallel with the noise exposure experiments. This allowed the experimental data to guide model development and allowied the model to suggest critical experiments needed for validation of elements and values in the model.

In this process, a dozen different experiments were run. Animals (10 per condition, both ears tested) were anesthetized at the time of the exposure to limit any movement, to eliminate middle ear muscle activity and to permit brain-stem evoked response audiometry just before and just after the exposures. The noise sources were primers, the M-16 rifle in a variety of configurations, and airbag deployments. The impulses ranged in pressure from 135 dB to 171 dB peak and from 1 to 50 impulses. In the end, the correlation between the model’s output and hearing loss measured immediately (about ½ hour post-exposure) had a correlation coefficient of 0.94. This high correlation between the model’s prediction and hearing loss led us to conclude that most of the variance was explained and the model was ready for transmogrification into human form. The equation for loss is:

 CTS = (26.6 * LN AHUs) - 140.1

Where:

CTS: Threshold shift ½ hour post-exposure in dB
AHUs: Auditory hazard units

Creation of the Human Model

Because of the similarity of mammalian ears, the same calculational structure that had worked for the cat was changed into human “form” by the selection of appropriate values for the structures of the ear. These values were coefficients in the equations and by selection of one set or the other, the model could be cat or human.

The values for the conductive paths of both the cat and human are reasonably well understood; however for obvious reasons there are essentially no data for the patterns of activity on the human basilar membrane in a live cochlea. Therefore, as a reasonable first estimate, the stapes displacement to basilar membrane displacement ratio was set the same for the mid-range human cochlea as it was for the mid-range cat cochlea. The design was “fixed” in 1997 with the understanding that as human data were tested, the model could be revised to correct any anomalies. Thus far, correspondence between the hearing loss data and the model’s predictions has been quite good; therefore the model has stayed in its original form.

Validation of the Human Model

The model’s values had been adjusted to create a proper conductive path, with the correct impedance for the human ear. And as noted earlier, the stapes displacement-to-basilar membrane displacement ratio had been set to the same value as for the cat. The same equation of loss (relating AHUs to threshold shift) was used for the human cochlea as for the cat cochlea. Up to this point, no human hearing loss data had been used in setting any values in the model.

Human data – protected hearing. As part of meeting the need for an improved DRC for noise, the Army Medical R&D Command had conducted an extensive series of studies with human volunteers, under a contract with EG&G, known as “The Albuquerque Studies”. In this work, groups of 60 subjects were exposed to impulses intended to simulate weapon impulses in the open and in one case, in a reverberant environment. On the test ear they wore an ear muff (in one series of exposures) or an ear muff that had eight holes in its seal. Peak pressures in the free field went from the upper 170 dBs to about 195 dB. In all, 53 conditions were tested. This data set is the largest and most completely documented in existence for such exposures, especially since it included waveforms measured in the free field and under the muff(s).

The goal of the Army’s program is to establish a DRC that will avoid threshold shifts 25 dB or greater (measured just after the exposure) in response to intense impulses in 95% of the exposed population. The presumption is that threshold shifts of 25 dB or less should result in minimal permanent threshold shift. Therefore the model was set to predict threshold shift for the 95th percentile subject and the Albuquerque waveforms were run through the model. In all but three cases its output and the data agreed on the 95th percentile outcome. In the three cases in which there was a disagreement, the model over-predicted the hazard loss for 50 and 100 impulses in the fully protected 5 meter condition at Level 6 and for 3 impulses at Level 6 in the reverbrant condition. In contrast, MIL STD-1474, the current DRC, predicted correctly in 20 instances and over-predicted hazard in the remaining 33 instances. A prediction based on A-weighted energy predicted correctly in 13 instances and over-predicted hazard in the remaining 40 instances.

Human data – unprotected hearing. There are several reasons why there is little usable data from recent studies using human exposures with unprotected hearing. Given the fact that weapon impulses can and do produce permanent losses in hearing, there has been essentially no experimental work with unprotected human ears since the 1960’s. In addition, the model needs a digitized waveform to process and there are few recorded pressure histories from that era. Furthermore, older studies generally ran too few subjects to permit characterization of the 95th percentile response.

However, a few analytical possibilities do exist. Work with impulse noise exposures at the former Human Engineering Laboratory with rifle and rocket impulses and three different exposures conducted by the German Army with rifle impulses provided enough data to allow at least a tentative comparison with the model. One study by the U.S. Army Medical Research Laboratory using spark-gap discharges also provided data that are indicative.

In the experiments with unprotected hearing, AHAAH was correct in its predictions (more than a dozen additional tests). An A-weighted energy measure under-predicted the hazard for two of the rifle impulses.

Acceptance and Potential Use of the Model

The analyses just cited show that AHAAH has been correct in 95% of the tests with protected hearing and 96% of the instances for all tests. MIL STD-1474 has been correct 38% of the time (protected hearing only) and A-weighted energy has been correct 24% of the time for protected hearing and 30% of the time for all tests analyzed.

A significant part of the development of the model has been the investment in making it user-friendly. In its present form, it runs on a PC in essentially real-time and operates in WINDOWS. Algorithms have been included for importing, editing and analyzing waveforms. The only requirement is that the waveforms be written in ASCII, a common format used around the world.

AHAAH is gaining acceptance as a noise analysis method outside the Army. The model has been presented to the automotive industry in this country and Europe (Germany) and the Society of Automotive Engineers committee on Inflatable Restraints is using it in the evaluation of airbag design and safety. A draft ANSI noise standard now being circulated includes the model for use. Weapons developers and designers have also been briefed at Picatinny Arsenal, New Jersey, and have expressed interest in using it. However, until the Surgeon General accepts it as a standard, their interest is essentially academic. See AIBS Peer-Review

Given that the model is theoretically based and structured like the ear, it opens new analytical possibilities for the design and fielding of safer, more effective systems. For instance, under the present standard, all hearing protective devices are rated as equal. Thus, there is no impetus to improve their attenuating characteristics. Alternatively, the weapons themselves could be made safer by options other than reducing the peak pressure (with the attendant limitations on performance). For example, small barriers produce significant sound shadows, but because the peak pressure and B-duration of the impulse is changed little by such devices, under the current standard their beneficial effects are simply ignored.

Relevant Publications/Talks

Kalb, J. T. (2001) “Firing weapons from enclosures: Predicting the hearing hazard”, To be presented at the International Conference on Military Noise, April 2001, Baltimore, MD
Price, G. R. (2001) “New perspective on protecting hearing form intense impulse noise” To be presented at the International Conference on Military Noise, April 2001, Baltimore, MD
Price, G. R. (2000) “ARL Auditory Model Applied to MACS”, invited presentation to MACS Project manager, Picatinny Arsenal, Dover, N.J. (August)
Price, G. R. (1999). “Auditory hazard from airbags: New perspectives”, Invited talk to UBA-Commission on Socioacousis of the Federal Environmental Agency (Germany), March 1999, Berlin
Royster, J. D., Royster, L. H., Price, G. R., McMillan, P. M. and Kileny, P. R. (1999). “Hazard analysis for a bicycle horn which produced acoustic trauma”, 24th Annual NHCA Hearing Conservation Conference Proceedings, Atlanta, GA 25-27 Feb.
Price, G. R. and Kalb J. T. (1999). “Application of AHAAH to impulse noise from MAAWS”,. Briefing to project engineers for MAAWS weapon system, APG, MD 21 Jan 99
Price, G. R. (1999). “Airbag noise as an issue on the highways”, Invited talk to Traffic Noise Committee of the National Transportation Research Board, Washington, D.C. 12 Jan 99
Mattox, D. E., Lou, W., Kalb, J. T. and Price, G. R. (1998). “Histologic changes in the cochlea after automobile airbag deployment”, In preparation.
Price, G. R. and Kalb, J. T. (1998). “A New Approach: The Auditory Hazard Assessment Algorithm (AHAA)” Talk to International Conference on Biological Effects of Noise – Australia, Conference Programme and Abstract Book, p. 127 also Conference Proceedings, 2, 725-728.
Price, G. R. and Kalb, J. T. (1998). “Design and noise measurement guidance for airbag design”, Talks presented to consortium of German automotive engineers at Porsche, Weissach, Germany. 26-27 Oct 98.
Price, G. R. and Kalb, J. T. (1998). “Implications of mathematical model of the human ear for weapons design”, Talk to design engineers, U. S. Army TACOM Armament Research, Development and Engineering Center, Picatinny Arsenal, New Jersey. 7Oct98.
Price G. R. and Kalb, J. T. (1998). “Development and validation of an Auditory Hazard Assessment Algorithm for the Human ear (AHAAH) as a predictor of hearing hazard and as an engineering tool”, In: TNO-report TM-00-I008, Report from NATO Research Study Group RSG.29 (Panel 8 – AC/243) Reconsideration of the effects on impulse noise, 1998 meeting, pp. 6-10. Also presented at TNO, October 1998, Soesterburg, The Netherlands.
Price, G. R. (1998) “Airbag noise hazard: from theory toward validation”, J. Acoust Soc. Am., 104, 1769. Invited presentation, Fall Meeting Acoustical Society of America, Norfolk, VA
Price, G. R. (1998). “Susceptibility to hearing loss: physiological, physical, behavioral and probabilistic factors”, J. Acoust. Soc. Am., 104, 1752. Invited presentation, Fall meeting ASA, Norfolk, VA
Price, G. R. and Kalb, J. T. (1998). “Hearing protectors and hazard from impulse noise: melding method and models”, J. Acoust. Soc. Am.103, 2878. Invited paper ICA/ASA meeting Seattle, WA Also paper in Proceedings ICA/ASA, pp. 1145-1146.
Kalb, J. T. and Price, G. R. (1998). “Modeling the effect of a hearing protector on the waveform of intense impulses”, J. Acoust. Soc. Am. 103, 2878 paper at joint ICA/ASA meeting Seattle, WA Also paper in Proceedings ICA/ASA pp. 1149-1150.
Price, G. R. (1998). “Standard for Damage Risk for Impact/Impulse Noise” in proceedings of 23rd Annual NHCA Hearing Conservation Conference, Albuquerque, NM. 10pp (Invited paper)
Price, G. R. (1998) “Modeling impulse noise susceptibility in marine mammals”, Invited presentation to USNRL workshop on Noise and Marine Mammals, Washington, D.C.
Price, G. R. (1998) “Engineering issues in reducing auditory hazard from airbags”, Presentation to SAE Committee on Airbag Noise, Detroit, MI. (Invited)
Price, G. R. (1998). “Airbags and the ear – a story (of) unfolding”, Invited article in NHCA’s Spectrum
Price, G. R. (1997). Airbag noise hazard examined with mathematical model of the human ear”, J. Acoust. Soc. Am., 102, 3201.
Price, G. R. and Kalb, J. T. (1997). “Progress in the development and validation of the human hazard model”, presented to meeting of the 1997 meeting of NATO RSG 29, Centre for Human Sciences, DERA, Farnborough, UK
Price, G. R. (1997). “Auditory hazard from airbag deployments”, Invited testimony to National Transportation Safety Board Public Forum on Airbags and Child Passenger Safety, Washington, DC.
Price, G. R (1997). “Understanding hazard from intense sounds”, Invited seminar to Audiology Department, University of Maryland Medical School, Baltimore, MD
Price, G. R. (1997). “Noise hazard issues in design standards for airbags” Invited seminar to SAE committee on Airbags, SAE meeting, Detroit, MI.
Price, G. R. (1997). “Noise hazard issues in the design of airbags” invited seminar presented to Ford Motor Company Advanced Engineering Center, Dearborn, MI.
Price, G. R. (1997). “Noise hazard issues in the design of airbags” Invited seminar presented to GM-NAO R&D Center, Warren, MI.
Price, G. R. (1997). “Predicting and ameliorating hearing hazard from the noise of air bag deployment” Invited presentation to meeting of Washington D.C. chapter of the Acoustical Society of America, Baltimore, MD.
Mattox, D.E., Lou, W., Kalb, J. T. and Price, G. R. (1997). “Histologic changes of the cochlea after airbag deployment” In Abstracts of the twentieth midwinter meeting of the Association for Research in Otolaryngology, St. Petersburg, FL, 3797, p. 200.
Price, G. R. (1996). “Auditory hazard from airbag noise”, Invited presentation to Insurance Institute for Highway Safety, 18 Dec 96, Arlington, VA.
Kalb, J. T and Price, G. R. (1996). “Modeling biophysical systems with electroacoustic elements” Presented to meeting of NATO RSG 29, on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Kalb, J. T and Price, G. R. (1996). “Mathematical models of the ear: transfer functions from free field to the cochlea”, Presented to meeting of NATO RSG 29, on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Price, G. R. and Kalb, J. T (1996). “Modeling the hazard from intense sounds: the nonlinear middle ear, energy dissipation within the middle ear, middle ear muscle activity, and intracochlear mechanisms” Presented to meeting of NATO RSG 29, on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Price, G. R. and Kalb, J. T. (1996). “Validation of the model with hearing loss data”, Presented to meeting of NATO RSG 29 on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Price, G. R. and Kalb, J. T. (1996). “Issues in using a model as a DRC: hearing protectors, source azimuth, and random incidence corrections”, Presented to meeting of NATO RSG 29 on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Price, G. R. and Kalb, J. T. (1996). “Extension of the model as an engineering design tool”, Presented to meeting of NATO RSG 29 on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Price, G. R. and Kalb, J. T. (1996). “Practical application of the model to current RSG problems”, Presented to meeting of NATO RSG 29 on Reconsideration of the Effects of Impulse Noise (AC/243, Panel 8), APG, MD.
Price, G. R. and Kalb, J. T. (1996) “Evaluation of hazard from intense sound with a mathematical model of the human ear”, J. Acoust. Soc. Am, 100, 2674 Invited paper at joint meeting of ASA and Acoust Soc. Japan, Honolulu, HA
Price, G. R., Rouhana, S. W., and Kalb, J. T. (1996). “Hearing hazard from the noise of air bag deployment”, J. Acoust. Soc. Am., 99, 2464.
Price, G. R. and Kalb, J. T. (1996). “Modeling auditory hazard from impulses with large low-frequency components”, J. Acoust. Soc. Am., 99, 2464.
Price, G. R. (1996). “Noise hazard from air bags – engineering insights”, Invited seminar presented at Ford Motor Company Advanced Engineering Center, Dearborn, MI .
Mattox, D. E. and Price, G. R. (1995). “Acoustic properties of automobile air bag deployment”, Paper at 18th Midwinter meeting of Assoc for Research in Otolaryngol, St. Petersburg, FL, (p 168 in Proceedings)
Price, G. R. (1995). “Heuristic value of a mathematical model of the effect of intense sound on hearing,” Invited seminar presented at SUNY Buffalo, Buffalo, NY
Price, G. R., Pierson, L. L., Kalb, J. T and Mundis, P. (1995). “Validating a mathematical model of noise hazard with varying numbers of rounds and peak pressures produced by a rifle”, J. Acoust. Soc. Am. 97, 3343
Pierson, L. L., Price, G. R., Kalb, J. T. and Mundis, P. A. (1995). “Comparison of impulse noise effects generated by two rifle muzzles”, J. Acoust. Soc. Am., 97, 3344.
Price, G. R. (1994). “Impulse noise standards, air bag noise and design implications of from a hearing loss model,” Invited presentation to seminar at GM-NAO R&D Center, Warren, MI.
Price, G. R. (1994). “Hazard from impulse noise: Problems and prospects,” J. Acoust. Soc. Am. 95, 2861-2862 (invited paper).
Price, G. R. (1994). “Occasional exposure to impulsive sounds: Significant noise exposure?” Proceedings of 1994 Meeting of National Hearing Conservation Association, Atlanta, GA (invited paper).
Price, G. R. (1993). “Integrated mathematical model of the ear. II. Application and insights,” J. Acoust. Soc Am. 93, 2313.
Price, G. R. (1992) “Sources of variability in the ear’s response to impulse noise”, J. Acoust. Soc. Am. 92, 2408.
Price, G. R. “Importance of Spectrum: Theoretical Basis” in Noise-Induced Hearing Loss edited by Dancer, Henderson, Salvi & Hamernik, (St. Louis: Mosby Year Book, 1992 ) pp 349-360.
Price, G. R. (1991). “Middle ear muscle effects during gunfire exposures,” J. Acoust. Soc Am. 89, 1865.
Price, G. R. and Kalb, J. T. (1991). “Insights into hazard from intense impulses from a mathematical model of the ear”, J. Acoust. Soc. Am. 90, 219-227.
Price, G. R. and Kalb, J. T. (1990). “Rating Hazard from Intense Sounds Through Theoretically Based Non-Linear Mathematical Modeling,” AAAS Annual Meeting Abstracts, p. 178.
Price, G. R. and Kalb, J. T. (1990). “Importance of Spectrum: Theoretical Basis” 4th International Symposium on Noise-Induced Hearing Loss, Beaune, France. (invited paper)
Price, G. R. (1990). “Firing Recoilless Weapons from within Enclosures”, Scand. Audiol. Suppl 34, 39-48.(invited paper) Also HEL TM 20-91.
Price, G. R. and Kalb, J. T. (1990). “A New Approach to a Damage Risk Criterion for Weapons Impulses”, Scand. Audiol. Suppl 34, 21-37.(invited paper) Also HEL TM 19-91.
Kalb, J. T. and Price, G. R. (1989). “Critical insights for impulse noise hazard from mathematical and physiological models,” Invited talk given to annual meeting in French-German Research Institute, Saint-Louis, France.
Price, G. R., Kim, H. N., Lim, D. J. and Dunn, D. (1989). “Hazard from weapons impulses: Histological and electrophysiological evidence,” J. Acoust. Soc. Am. 85, 1245-1254. Also HEL TM 1-89.
Price, G. R. and Wansack, S. (1989). “Hazard from an intense mid-range impulse,” J. Acoust. Soc. Am. 86, 2185-2191.
Price, G. R. (1989) “Growth of threshold shift from intense impulses: Implications for basic loss mechanisms”, J. Acoust. Soc. Am. 85, S47.
Price, G. R. and Kalb, J. T. (1989). “Impulse Noise Model and Its Implications. Presented to meeting of NAS/NRC Committee on Hearing, Bioacoustics and Biomechanics (CHABA), Washington, D.C. (invited paper)
Price, G. R. and Kalb, J. T. (1988). “Weapons design and the inner ear: Critical insights from mathematical and physiological models. Proceedings of Army Science Conference.
Price, G. R. (1988) “Rating auditory hazard in the blast/overpressure environment,” In: Proceedings of the Live Fire Test Crew Casualty Assessment Workshop, held at Groton, CN – Sponsored by (ADDDRE(T&E)/LFT)
NATO RSG6/PANEL8 (1987). “The effects of impulse noise”, Document AC/243/(PANEL8/RSG.6)D/9, NATO, 1110 Brussels, 33pp.
Kalb, J. T. and Price, G. R. Mathematical model of the ear’s response to weapons impulses. In: Proceedings of the Third Conference on Weapon Launch Noise Blast Overpressure, U.S.Army Ballistics Research Lab, Aberdeen Proving Ground, MD 21005-5001, 1987.
Price, G. R. and Kalb, J. T. A mathematical model for hearing loss to intense impulses. Paper presented at Symposium on noise-induced hearing loss at 10th meeting of Association for Research in Otolaryngology, Clearwater Beach, FL, Feb 1987.
Price, G. R. The need for a new DRC for impulse noise,” In: Proceedings of the Third Conference on Weapon Launch Noise Blast Overpressure, U.S.Army Ballistics Research Lab, Aberdeen Proving Ground, MD 21005-5001, 1987
Price, G. R. The place of animal models in impulse noise research. Paper presented to a meeting on Effects of shock and vibration in the military environment, Technical Establishment of Bourges, Bourges, France, June, 1987.
Price, G. R. and Kalb, J. T. Insights in the hazard from intense impulses from a mathematical model of the ear. Paper in proceedings of Inter-Noise 87, meeting in Beijing, China, Sept 1987.
Price, G.R. (1986). Hazard from intense low-frequency acoustic impulses. Journal of the Acoustical Society of America, 80, 1076-1086. (Also USAHEL TM 14-86)
Price, G.R. (1986). Impulse noise hazard as a function of level and spectral distribution. In R.J. Salvi, D. Henderson, R.P. Hamernik, and V. Coletti (Eds.), Basic and Applied Aspects of Noise-Induced Hearing Loss. Plenum Press. pp 379-392. (Also USAHEL TM 3-87)
Price, G.R., & Kalb, J.T. (1986). Mathematical model of the effect of limited stapes displacement on hazard from intense sounds. Journal of the Acoustical Society of America, 80, S123.
Price, G.R., & Wansack, S. (1985). A test of maximum susceptibility to impulse noise. Journal of the Acoustical Society of America, 77, S82.
Price, G.R. (1984). Application of basic research to industrial impulse noise issues. In Proceedings of INTER-NOISE 84 (pp. 261-264).
Price, G.R. (1984). Model for threshold shift following intense exposures. Journal of the Acoustical Society of America, 75, S6.
Price, G.R. (1983). Relative hazard of weapons impulses. Journal of the Acoustical Society of America, 73, 556 566.
Price, G.R., & Lim, D.J. (1983). Susceptibility to intense impulses. Journal of the Acoustical Society of America, 74, S8.
Price, G.R. (1983). A damage-risk criterion for impulse noise based on a spectrally dependent critical level. In Proceedings of the 11th International Congress on Acoustics, 3, 261-264.
Price, G.R. (1983). Mechanisms of loss for intense sound exposures. In R.R. Fay and G. Gourevitch (Eds.), Hearing, and other senses: Presentations in honor of E.G. Wever (pp. 335-346). Groton, CT: Amphora.
Price, G.R. (1982). Relative hazard of weapons impulses as a function of spectrum. Journal of the Acoustical Society of America, 71, S79.
Price, G.R. (1982). “A-weighting and the rating of auditory hazard. Journal of the Acoustical Society of America, 72, S25.
Price, G.R. (1982). Impulse noise measurement: the physiological basis. Journal of the Acoustical Society of America, 72, S52.
Price, G.R. (1982). Rating the hazard from intense sounds: Putting theory into practice. In H.M. Borchgrevink (Ed.), Hearing and hearing prophylaxis, Scandinavian Audiology Supplement 16 (pp. 111-121).
Price, G.R. (1982). Modeling the loss process: Indications for a new risk assessment. In Technical Proceedings of the Blast Overpressure Workshop, (pp. 432-446). Dover, NJ: USAARADCOM.
Price, G.R. (1981). Implications of a critical level in the ear for the assessment of noise hazard at high intensities. Journal of the Acoustical Society of America, 69, 171-177.
Price, G.R. (1981). Assumptions in the measurement of impulse noise. Sound and Vibration, 15, 8-9.
Hodge, D.C., Price, G.R., Dukes, N.L., & Murff, S.J. (1979). Effects of artillery noise on the hearing of protected crew personnel (USAHEL Technical Memorandum 17-79). Aberdeen Proving Ground, MD: U.S. Army Human Engineering Laboratory.
Price, G.R. (1979). Loss of auditory sensitivity following exposure to spectrally narrow impulses. Journal of the Acoustical Society of America, 66, 456-465.
Price, G.R. (1978). Firing from enclosures with 90mm recoilless rifle: Assessment of acoustic hazard (USAHEL Technical Memorandum 11-79). Aberdeen Proving Ground, MD: U.S. Army Human Engineering Laboratory.
Price, G.R. (1974). Transformation function of the external ear in response to impulsive stimulation. Journal of the Acoustical Society of America, 56, 190 194.
Price, G.R. (1974). An upper limit to stapes displacement: Implications for hearing loss. Journal of the Acoustical Society of America, 56, 195-197.
Price, G.R. (1972). Functional changes in the ear produced by high intensity sound. II. 500-Hz stimulation. Journal of the Acoustical Society of America, 51, 552 558.
Price, G.R. (1968). Functional changes in the ear produced by high intensity sound. I. 5.0-kHz stimulation. Journal of the Acoustical Society of America, 44, 1541 1545.