[Study of the cochlea by evoked otoemissions. Physiological interpretation of results].

Amplitudes and detection thresholds of evoked otacoustic emissions (EOE) were measured in various groups of subjects: 44 normal young adults, 80 patients with presbycusis and 38 patients with acoustic trauma. Relations between these EOE parameters and tonal audiogram were analyzed. Surprisingly, EOE detection threshold at 1 kHz was strongly correlated with auditory threshold at 2 kHz and no other one. This result demonstrates that some EOE parameters are not frequency-specific. A simple model is implemented in which it is assumed that EOE amplitudes are proportional to the global cochlear activity. This model fits very well experimental data and allows a quantitative evaluation of the residual cochlea. The domain of validity of EOE test in clinics has therefore been precised.