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Biomedical subjects

T L Wiley

Publications and source records attributed to T L Wiley.

49 records · Page 3Linked to original sources
PubMed1975

Acoustic-reflex response to sustain signals.

Acoustic-reflex activity was observed for 10 normal-hearing young adults using three sustained activating signals: 500-Hz tone, 4000-Hz tone, and broad-band noise. Reflex activity was observed over a period of three to five minutes at activator levels of 5, 10, and 15 dB above individual acoustic-reflex thresholds. General findings were that (1) acoustic-reflex adaptation was present to some degree for all three activating signals, (2) the amount of reflex adaptation varied with the spectrum of activating signals (reflex adaptation was greatest for the 4000-Hz activator, less for the noise activator, and least for the 500-Hz activating signal), (3) the rate of reflex adaptation differed with activator spectrum (reflex-adaptation rate was relatively rapid for the 4000-Hz activator, slower for noise, and much slower for the 500-Hz activating signal), and (4) reflex adaptation did not appear to vary systematically with activating-signal level except for the 500-Hz activator, in which case reflex adaptation appeared to begin earlier in time and to be of greater magnitude as the activating-signal level was increased.

Acoustic Stimulation↗
PubMed1975

Separate roles of sodium ion concentration and fluid volumes in salt-loading hypertension in sheep.

The goal of these studies was to determine whether the hypertension caused by excessive salt loading results from sodium-induced expansion of the extracellular fluid volume or whether the salt increases the pressure in some other way, such as by causing vascular constriction. In one group of sheep, a combination of total nephrectomy and hemodialysis was used to produce and maintain step increases in extracellular fluid volume for 1 wk without a significant change in sodium ion concentration. In a 2nd group, unilateral nephrectomy, dialysis, and DOCA administration were used to cause step increases in sodium ion concentration while the extracellular fluid volume was held as close to normal as possible. The results showed a 41% increase in arterial pressure in the high-volume sheep and only a 4% increase in pressure in the high-sodium sheep. In both instances the total exchangeable sodium increased almost equally--a 21% increase in the high-sodium sheep. The data support the concept that sodium retention causes hypertension almost entirely because of sodium-induced expansion of the extracellular fluid volume.

Animals↗
PubMedDate not supplied

Diphtheria and hearing loss.

OBJECTIVE: To determine if infectious diseases usually experienced in childhood have an effect on hearing ability later in life. METHODS: The Epidemiology of Hearing Loss Study (N = 3,753) is a population-based study of age-related hearing loss in adults aged 48 to 92 years in Beaver Dam, Wisconsin. As part of this study, infectious disease history was obtained and hearing was tested using pure-tone audiometry. Hearing loss was defined as a pure-tone average of thresholds at 500 Hz, 1,000 Hz, 2,000 Hz, and 4,000 Hz greater than 25 decibels hearing level in either ear. RESULTS: After adjusting for confounders, only a history of diphtheria (n = 37) was associated with hearing loss (odds ratio [OR] 2.79; 95% confidence interval [CI] 1.05, 7.36). There was no relationship between hearing loss and history of chickenpox, measles, mumps, pertussis, polio, rheumatic fever, rubella, or scarlet fever. Only two participants with a history of diphtheria and hearing loss reported having a hearing loss before age 20. CONCLUSIONS: Diphtheria in childhood may have consequences for hearing that do not become apparent until later in life. A possible biological mechanism for a diphtheria effect on hearing ability exists: The toxin produced by the Corynebacterium diphtheriae bacteria can cause damage to cranial nerves and therefore may affect the auditory neural pathway. These data may have important implications for areas facing a resurgence of diphtheria cases.

Adult↗
PubMedDate not supplied

Consonant discrimination as a function of presentation level.

This study examined the effect of presentation level (seven levels ranging from 0 to 60 dB re the subject's SRT) on the discrimination of 20 consonants spoken in CV syllables. The subjects were 10 young adults with normal hearing. It was determined that the performance-intensity functions for individual consonants varied widely. Some sounds were not identified correctly 100% of the time even at the highest level tested, whereas other sounds were consistently identified at 10 dB SL. The data were considered with respect to stimulus and response bias and also were subjected to a feature analysis using features of voice, manner and place.

Adult↗
PubMedDate not supplied

Accuracy of self-reported hearing loss.

The purpose of this study was to assess the accuracy, in older adults, of questions assessing hearing loss. Study participants (n=3,556), aged 48-92 years, were examined in a population-based study of age-related hearing loss in Beaver Dam, Wisconsin. Self-report data from the ten-question Hearing Handicap Inventory for the Elderly-screening Version (HHIE-S), and four additional questions were compared with hearing loss as measured by pure-tone air conduction audiometry. The single question, 'Do you feel you have a hearing loss?' was the most sensitive question (sensitivity=71 per cent); its overall and gender-specific prevalence estimates were within 3.2 per cent of prevalence measures derived audiometrically, although age-group specific estimates were not as accurate. Using an HHIE-S total score >8 resulted in low sensitivity (34 per cent) and inaccurate prevalence estimates. These results indicate that, for some applications, one simple question may be sufficient for prevalence surveys of hearing loss among older adults.

Adult↗
PubMedDate not supplied

Association of leisure-time noise exposure and hearing loss.

The purpose of this study was to investigate the association of noisy leisure activities with hearing loss. Participants (n=3571) were examined in a population-based study of age-related hearing loss conducted in Beaver Dam, Wisconsin. Hearing thresholds were determined by audiometry. Hearing loss was defined as the pure-tone average of the frequencies 500, 1,000, 2,000, and 4,000 Hz greater than 25 dB HL in either ear. Information regarding exposure to leisure-time noise was obtained by interview. After adjusting for potential confounders, individuals who engaged in leisure activities with average sound levels greater than 90 dBA were significantly more likely to have a hearing loss than participants who did not engage in noisy leisure activities (OR=1.11, 95 per cent CI=1.01-1.22). Individuals who engaged in woodworking were 30 per cent more likely to have a hearing loss than those who had never done woodworking. There was a 6 per cent increased risk of hearing loss for each 5-year period of participation. Health care professionals should consider counseling their patients who engage in noisy leisure activities about the risk of noise-induced hearing loss.

Aged↗
PubMedDate not supplied

Hearing sensitivity in adults screened for selected risk factors.

As a means of partially distinguishing age effects and other risk factors in presbyacusis, hearing thresholds for 56- to 65-year-old participants screened for exclusion of selected risk factors were compared with thresholds for 48- to 55-year-old participants without the same risk factors. Hearing thresholds for both age groups were also compared with age-appropriate International Standards Organization (ISO) norms. Even after screening participants for exclusion of selected risk factors, differences in hearing sensitivity remained across age groups. Across the male and female groups, thresholds were generally better (lower) for 48 to 55 year olds than for 56 to 65 year olds. ISO norms generally underestimated the degree of hearing loss for participants of comparable age in the present study. The underestimation was small at lower test frequencies, was generally greater for men, and was largest at test frequencies above 2000 Hz.

Age Distribution↗
PubMedDate not supplied

Hearing sensitivity in farmers.

Hearing sensitivity was measured for tones from 1,000 through 8,000 hertz (Hz) in 534 males and 278 females who resided in rural Wisconsin and ranged in age from 16 to 85 years. The hearing sensitivity for all subjects decreased with advancing age and at higher frequencies, but hearing loss over the range most susceptible to excessive noise exposure (3,000-6,000 Hz) was much greater for males than for females at all ages. The hearing loss was greater than could be accounted for by age and was similar whether the subject was a farmer or not. The results suggested that approximately 25 percent of the males had a communication handicap due to hearing loss by age 30, and the proportion rose to 50 percent by age 50. Less than 20 percent of farmers reported consistent use of personal hearing protection in their farm-related duties. Overall, the findings suggest that men who live in rural areas, including farmers, demonstrate a high prevalence of hearing loss and associated communication problems due to excessive noise exposure. This, in turn, clearly indicates a need for intensification of educational hearing conservation programs for the rural population.

Adolescent↗
PubMedDate not supplied

Recovery characteristics of the acoustic reflex.

Acoustic-reflex recovery time was measured as a function of activator intensity level and duration for broad-band noise and a 500-Hz tone in 10 normal-hearing subjects. The activating signals were presented at 5 and 10 dB above individual acoustic reflex thresholds for durations ranging from 0.25 to 100 sec. Reflex-recovery times were similar across both activators and across activator intensity levels. Recovery time was relatively constant for activators of 2 sec or less and increased for longer activator durations. Portions of the results from temporary threshold shift experiments are explained on the basis of acoustic reflex recovery characteristics.

Acoustic Stimulation↗