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Biomedical subjects

W G Thomas

Publications and source records attributed to W G Thomas.

At least 73 records · Page 4Linked to original sources
PubMed1980

Recommended criteria for evaluating the effectiveness of hearing conservation programs.

Hearing level data from several North Carolina industrial populations is analyzed. The analysis considered several different test retest criteria as well as changes in hearing levels with time at different testing frequencies. The findings demonstrate the necessity fo subdividing the populations by race and sex. A characteristic of programs that are classified as acceptable is a significant improvement over the first four to six years of testing in the mean hearing levels (the learning curve) at 3, 4 and 6 kHz with respect to the baseline hearing test. A significant correlation is established between the change in the mean hearing level at 4 kHz and a test retest criterion defined as a shift in mean hearing level equal to or greater than 15 dB at any frequency tested in either ear.

Adult↗
PubMed1980

Age effect hearing levels for a black nonindustrial noise exposed population (NINEP).

A nonindustrial noise exposed population (NINEP) that describes the age effects for a black male and female population has been established. The mean hearing threshold levels for the black NINEP are significantly lower (better hearing) than the previously established mean HTLs for a white NINEP when compared by sex. The availability of the black NINEP now makes it possible to more accurately evaluate a typical industrial noise exposed population (INEP).

Adolescent↗
PubMed1980

Representative hearing levels by race and sex in North Carolina industry.

An extensive sample of North Carolina industrial audiometric test data has been compiled. The sample includes data from several different types of industrial environments, with the size of the industries represented ranging from less than fifty to over eight thousand employees. The total population considered is in excess of 14000 employees. The data are examined using analytical techniques developed over the past six years while investigating the effectiveness of industrial hearing conservation programs. One of the findings is significant differences in the initial hearing threshold levels by race and sex. A second observation is differences by race and sex in the change in haring levels with time It is concluded that the hearing levels of industrial employees differ significantly by race and sex. The differences are of such magnitude that meaningful evaluations of industrial audiometric data bases are not possible unless the race and sex compositions of the population are considered.

Adolescent↗
PubMed1979

Age effect hearing levels for a white nonindustrial noise exposed population (ninep) and their use in evaluating industrial hearing conservation programs.

A nonindustrial noise exposed population (NINEP) describing age effects for white males and females has been established that can be used as a reference in evaluating an industrial noise exposed population (INEP) data base. In making this comparison, it is desirable to match the two populations properly with respect to sex, race and age characteristics. Since there presently does not exist an equivalent black NINEP, it is necessary to first isolate the data representing the black population from the industrial sample. A definite learning curve exists in industrial audiometric data bases, with the degree of learning dependent upon the effectiveness of the hearing conservation program. Therefore, this variation must be considered when attempting to compare the industrial audiometric test data with the white NINEP data base presented herein.

Adolescent↗
PubMed1978

Presumed noise-induced permanent threshold shift resulting from exposure to an A-weighted Leq of 89 dB.

The noise-induced permanent threshold shift (NIPTS) resultings form up to ten years of exposure to an average A-weighted sound level Leq of 89 dB was investigated. Prior occupational noise exposure was controlled for by eliminating subjects with previous high-noise-level jobs or uncertain exposure histories. The final population consisted of 42 males and 58 females working a steady-state broadband noise environments. No attempt was made to screen subjects for any auditory pathology. A 222-subject control group from the same geographic area as the exposed subjects was selected such that none of its constituents had any effective industrial noise exposure. Presumed NIPTS was calculated by correcting each individual audiogram of the exposed subjects according to the aging curves developed from the control population hearing levels. The results indicated a considerable male-female difference in NIPTS, even though both groups were exposed to the same Leq. Averaging the results for all 100 subjects, in order to make comparisons to other available data, yielded results in close agreement to predictions based upon the work of Burns and Robinson, Baughn. NIOSH, and Passchier--Vermeer, indicating that 10 years of exposure to a daily Leq of 89 dB causes measurable hearing loss at 4 kHz.

Adult↗
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↗
PubMed1976

Inner ear decompression sickness.

With recent increases in commercial, military, and sport diving to deeper depths, inner ear injuries during such exposures have been encountered more frequently and noted during several phases of diving: during compression, at stable deep depths, with excessive noise exposure in diving, and during decompression. The pathophysiology of these injuries differs, depending upon the phase of diving in which the injuries occur. In this report, 23 cases of hearing loss, tinnitus, and/or vertigo occurring during or shortly after decompression are presented. Thirteen of these cases occurred in helium-oxygen dives involving a change to air during the latter stages of decompression. A significant correlation is present between prompt recompression treatment, relief of symptoms, and lack of residual deficits. Current knowledge indicates that the management of otologic decompression sickness should include: 1. prompt recompression to at least 99 feet deeper than the symptom onset depth; 2. recompression using the previous helium-oxygen mixture when the injuries occur during or shortly after a switch from helium-oxygen to air during the latter stages of decompression; 3. the use of parenteral diazepam for symptom relief and cyclic inhalations of oxygen enriched treatment gases; and 4. the avoidance of further diving by divers who exhibit permanent inner ear injuries after the acute symptoms have subsided.

Adult↗
PubMedDate not supplied

Practice effects in industrial hearing screening.

Two samples of employees were drawn at random from the total population of approximately 12,000 employees in one large company. The base-line audiograms and two subsequent annual retests were studies on a sample of 118 employees to determine whether the mean threshold values improved with subsequent years of testing. In addition, the audiometric earphones were reversed so that the right ear was tested first on an automatic audiometer, followed by the left ear on a different sample of 400 employees in an effort to determine whether there is a significant difference between the first and second ear tested. Results indicate that subsequent retests do not show significant improvements. It is possible, however, the small improvements of 1 or 2 dB reported by other investigators over several years of testing may not be seen when mean values are used on populations of this size. Of more importance, however, was the fact that a consistent and significant difference was seen between the first and second ear tested, with the first ear tested showing the poorer threshold. When earphones were reversed, the left or previously poorer ear, showed better thresholds than the right in the low- and midfrequencies. The right ear continued to show better thresholds in the high frequencies, regardless of which ear was tested first.

Audiometry↗