Characterizing individual differences: Audiometric phenotypes of age-related hearing loss
Metabolic presbyacusis, or the degeneration of the cochlear lateral wall and decline of the endocochlear potential, largely accounts for age-related threshold elevations observed in laboratory animals raised in quiet and may underlie the characteristic audiogram of older humans. The “audiometric phenotype” associated with metabolic presbyacusis differs from audiograms associated with sensory losses resulting from ototoxic drug and noise exposures. Evidence supporting metabolic and sensory phenotypes in audiograms from older adults can be derived from demographic information (age, gender), environmental exposures (noise and ototoxic drug histories), and stability or changes in audiometric phenotypes as individuals age. When confirmed with biological markers and longitudinal analyses, well-defined audiometric phenotypes of human age-related hearing loss can contribute to explanations of individual differences in auditory function for older adults.
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