Audiologic findings in presbycusis.

Presbycusic Ss (N: 64) were studied using tests for cochlear functions (SISI test, Metz test, delta F threshold, remote masking), for retrocochlear involvement (tone-decay test), and for central auditory impairment (tonal binaural MLD, ipsi- vs contralateral acoustic reflex). Recruitment was present in about half the cases; remote masking (supposed a test of stiffness of the cochlear partition) was almost always pathological; tone decay rarely was abnormal; tonal MLD and/or acoustic reflexometry yielded pathologic values in more than half of the Ss. Tonal test patterns demonstrated that in presbycusis there is a frequent alteration of the monaural and binaural analytic processes of intensity, frequency and phase; a constant increase of stiffness in the hydrodynamic system of acoustic energy transmission; and, sometimes, an increase of resistance of neural transmission.