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Biomedical subjects

J D Royster

Publications and source records attributed to J D Royster.

5 recordsLinked to original sources
PubMed1991

Subjective evaluation of a prototype earmuff exhibiting flat and nonlinear attenuation characteristics.

Subjective user responses were obtained for a test earmuff exhibiting approximately flat (uniform) attenuation of about 25 dB from 500 to 8000 Hz for sound pressure levels (SPLs) less than 120 dB. At SPLs above 120 dB, the test earmuff exhibited nonlinear (level-dependent) attenuation characteristics such that noise reduction increased with increasing sound level. The study population consisted of police officers from the Raleigh, North Carolina, Police Department as they were performing arms requalification by executing a series of firing programs during two sequential and identical relays. The study subjects wore either the test earmuff or a comparable conventional earmuff during the first relay, then the alternate protector for the second relay with the order counterbalanced. Results indicated a significant preference for the test earmuff in three comparison areas: comfort, perceived hearing protection, and speech understanding. The study demonstrates that ammunition type and level of noise exposure contributed significantly to a preference in favor of the test earmuff. The subjects who used the quietest of the ammunition types rated the test earmuff significantly better than the remaining subjects with respect to speech understanding.

Adult↗
PubMed1991

Sound exposures and hearing thresholds of symphony orchestra musicians.

To assess the risk of noise-induced hearing loss among musicians in the Chicago Symphony Orchestra, personal dosimeters set to the 3-dB exchange rate were used to obtain 68 noise exposure measurements during rehearsals and concerts. The musicians' Leq values ranged from 79-99 dB A-weighted sound pressure level [dB(A)], with a mean of 89.9 dB(A). Based on 15 h of on-the-job exposure per week, the corresponding 8-h daily Leq (excluding off-the-job practice and playing) ranged from 75-95 dB(A) with a mean of 85.5 dB(A). Mean hearing threshold levels (HTLs) for 59 musicians were better than those for an unscreened nonindustral noise-exposed population (NINEP), and only slightly worse than the 0.50 fractile data for the ISO 7029 (1984) screened presbycusis population. However, 52.5% of individual musicians showed notched audiograms consistent with noise-induced hearing damage. Violinists and violists showed significantly poorer thresholds at 3-6 kHz in the left ear than in the right ear, consistent with the left ear's greater exposure from their instruments. After HTLs were corrected for age and sex, HTLs were found to be significantly better for both ears of musicians playing bass, cello, harp, or piano and for the right ears of violinists and violists than for their left ears or for both ears of other musicians. For 32 musicians for whom both HTLs and Leq were obtained, HTLs at 3-6 kHz were found to be correlated with the Leq measured.

Acoustics↗
PubMed1986

Using audiometric data base analysis.

Audiometric data base analysis (ADBA) offers the most direct means of judging the effectiveness of a hearing conservation program (HCP) in preventing occupational hearing loss. However, numerous factors need to be accounted for if the findings are to be meaningful. This paper discusses several parameters known to influence the interpretation of group data statistics in assessing HCP effectiveness. Testing factors that affect the stability of the data base include audiometric techniques, calibration procedures, testing environment, and the motivation and prior experience of the subject. Pertinent population parameters include age, sex, race, current and prior noise exposures, learning effects, and the types of hearing protectors in use. Two case histories are presented to illustrate the application of ADBA techniques. Specific analysis procedures reviewed include comparisons of mean thresholds for selected industrial and nonindustrial populations, rates of change in mean hearing levels over a period of time, baseline and sequential test-retest comparisons, and different threshold shift criteria. The preliminary results of ADBA research being done by the American National Standards Institute (ANSI) S12.12 Working Group are summarized, including desirable criterion ranges for several statistics established by applying them to control data sets.

Audiometry↗
PubMed1978

Potential hearing compensation cost by race and sex.

A large general industrial population (n = 10,000) is analyzed using different low fences (15 bB HTL to 35 dB HTL) with the high fence held constant at 93 dB HTL. Three different audiometric test frequency combinations are considered: HTL.5,1,2 kHz, HTL.5,1,2,3 kHz and HTL1,2,3 kHz. The data base is analyzed first as a total population and then divided into different subpopulations including male, female, black and whites; and further subdivided into black males, black females, white males and white females. The findings indicate that significant differences exist between the groupings with respect to the potential hearing compensation cost and percent of a population exceeding the different low fence frequency combinations.

Costs and Cost Analysis↗