Abstract
The present study focuses on auditory discrimination abilities in older adults aged 65–89 years. We applied the “Leipzig inventory for patient psychoacoustic” (LIPP), a psychoacoustic test battery specifically designed to identify deficits in central auditory processing. These tests quantify the just noticeable differences (JND) for the three basic acoustic parameters (i.e., frequency, intensity, and signal duration). Three different test modes [monaural, dichotic signal/noise (s/n) and interaural] were used, stimulus level was 35 dB sensation level. The tests are designed as three-alternative forced-choice procedure with a maximum-likelihood procedure estimating p = 0.5 correct response value. These procedures have proven to be highly efficient and provide a reliable outcome. The measurements yielded significant age-dependent deteriorations in the ability to discriminate single acoustic features pointing to progressive impairments in central auditory processing. The degree of deterioration was correlated to the different acoustic features and to the test modes. Most prominent, interaural frequency and signal duration discrimination at low test frequencies was elevated which indicates a deterioration of time- and phase-dependent processing at brain stem and cortical levels. LIPP proves to be an effective tool to identify basic pathophysiological mechanisms and the source of a specific impairment in auditory processing of the elderly.
Highlights
It is well documented that hearing sensitivity is decreased in older adults (≥60 years of age; Brant and Fozard, 1990; Gates et al, 1990; Cruickshanks et al, 1998; Mazelová et al, 2003) a condition termed presbycusis (Schuknecht, 1955)
The present study focuses on auditory discrimination abilities in older adults aged 65–89 years.We applied the “Leipzig inventory for patient psychoacoustic” (LIPP), a psychoacoustic test battery designed to identify deficits in central auditory processing
The discrimination of sounds deviating in signal duration, intensity, and frequency is indicative of the status of these integrative processes and can be used for the evaluation of the influence of age and/or hearing loss on central auditory processing
Summary
It is well documented that hearing sensitivity is decreased in older adults (≥60 years of age; Brant and Fozard, 1990; Gates et al, 1990; Cruickshanks et al, 1998; Mazelová et al, 2003) a condition termed presbycusis (Schuknecht, 1955). The central auditory hypothesis is supported by the fact that adult hearing impaired subjects (even when equipped with digital hearing aids) and older people with (age-matched) normal hearing often complain about verbal communication problems, i.e., they suffer from impairments in speech- and especially in speech in noise comprehension (Humes, 1996; Pichora-Fuller and Souza, 2003; Divenyi et al, 2005; Tremblay et al, 2007). This is clear evidence of pathophysiological changes in central auditory processing. A number of studies quantified frequency, intensity, and duration discrimination in older adults which to different degrees covaried with hearing sensitivity (e.g., duration and frequency: Abel et al, 1990; frequency: König, 1957; Turner and Nelson, 1982; Freyman and Nelson, 1991; Buss et al, 2004; He et al, 2007; intensity and frequency: He et al, 1998)
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