Hearing thresholds

Audiogram The report produced by an audiometry test, showing measured hearing threshold levels at frequencies of 500, 1000, 2000, 3000, 4000, and 6000 Hz. 

Temporary threshold shift (TTS) A temporary shift in hearing threshold level that goes away after the person has been in a quiet environment for a few hours. It is confirmed by an audiogram retest following a suspected standard threshold shift (STS) after at least 14 hours away from high levels of noise. 

Suggestive evidence of a lead-related decrease in hearing acuity in children has been reported by Robinson et al. (1985) and Schwartz and Otto (1987, 1991). Hearing thresholds at 2,000 Hertz increased linearly with maximum blood lead levels, indicating that lead adversely affects auditory function. The PbB levels in 75 asymptomatic black children, 3-7 years old, ranged from 6 to 59 tg/dL (mean,... 

Hearing thresholds in children may be affected adversely by lead exposure at low blood lead levels (Robinson et al. 1985 Schwartz and Otto 1987, 1991). Robinson et al. (1985) reported that hearing thresholds increased linearly with maximum historical PbB levels of 6.2-56.0 pg/dL. In the analyses by Schwartz and Otto (1987, 1991), the probability of lead levels studied (NHANES II and HHANES data, respectively), from <4 to >50 pg/dL, with no apparent threshold. There is also some evidence suggesting that lead exposure may cause postural disequilibrium in children (Bhattacharya et al. 1993). The children evaluated in that study had a geometric mean PbB for the first 5 years of life of 11.9 pg/dL, the range was 5.1 to 28.2 pg/dL. 

Schwartz J, Otto DA. 1987. Blood lead, hearing thresholds, and neurobehavioral development in children and youth. Arch Environ Health 42 153-160. 

An absolute sound scale (in dBA for absolute decibels) is defined by establishing an intensity reference. For convenience, the hearing threshold is set at 0 dBA. Table 3-7 contains dBA levels for a variety of common activities. 

Threshold of good hearing Threshold of excellent youthful hearing... 

Fig. 5. Observed hearing threshold shift (dB) at 1, 2 and 4 kHz versus measured unbound (upper panel) and total plasma quinine concentration in a subject who received a computer-controlled quinine infusion. The reduced sigmoid Fmax model has been applied and is shown as the solid line. Note that the y axis is hy definition a log scale. (From Karlsson KK, Beminger E, Gustafsson LL, Al-van G. Pronounced quinine-induced cochlear hearing loss. A mechanistic study in one volunteer at multiple stable plasma concentrations. J Audiol Med 1995 4 12-24, with permission.)...

Fig. 6. Counterclockwise hysteresis appearing between hearing threshold shift and quinine plasma concentration in a subject who received two identical oral doses (dotted and solid lines) and an infusion (dashed line) of quinine. (From Paintaud G, Alvan G, Beminger E et al. The concentration-effect relationship of quinine-induced hearing impairment. Clin Pharmacol Ther 1994 55 317-23, with permission from MOSBY Inc.)...

Table 6.1 Hearing thresholds, descriptive terms, and probable handicaps (after Goodman, 1965)...

In a prospective multicenter study in 152 children with peritoneal dialysis-associated peritonitis one patient with vancomycin intoxication had a 20-30 dB increase in hearing threshold (35). 

Nakagawara VB, Montgomery RW, Dillard A, McLin L, and Connor CW (2003) The effects of laser illumination on operational and visual performance of pilots conducting terminal operations. DOT/FAA/AM-03/12. Niskar A, Kieszak S, Holmes A, et al. (2002) Estimated prevalence of noise-induced hearing threshold shifts among children 6 to 19 years of age The Third National Health and Nutrition Examination Survey 1988-1994. Pediatrics 109 987-988. 

As discussed in Section 13.3 concurrent exposure to noise and some organic solvents and solvent mixtures is ototoxic. Styrene is an example of an ototoxic compound, with exposures to it causing permanent hearing threshold shifts and outer hair cell damage. Ethanol alone does not affect auditory sensitivity, yet, when combined with styrene it induces hearing and outer hair cell losses in test animals in levels greater than those caused by styrene alone. The potentiation of the ototoxicity of styrene by ethanol is ascribed to the altering of styrene metabolism by ethanol. 15 ... 

The toxicity of gentamycin to the ear may be detected by histopathology or more easily by the Preyer reflex test which measures hearing thresholds for particular sound frequencies. 

CHRONIC HEALTH RISKS weight loss weakness anemia neurological symptoms blood pressure effects affects hearing threshold and growth in children interference with vitamin D metabolism severe depression of sperm counts decrease function of the prostate impaired mental development decease IQ scores in children spontaneous abortion low birth weight. 

Degree of Hearing Loss Hearing Threshold Range (dB)... 

Audiometric Testing— Measures the hearing threshold of employees. 

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