Loudness estimation through evoked responses at audiometric frequencies

Abstract

Procedures for evaluating individual loudness functions through tone burst evoked auditory responses - both Tone-Burst Otoacoustic Emissions (TBOAE) and Tone-Burst Auditory Brainstem Responses (TBABR) - have been investigated in the past and have yielded credible results for a limited stimulus frequency range across a wide range of levels. The aim of this work is to investigate this relationship further by expanding the frequency range examined to cover a more full audiometric range and expand the analysis parameters for an objective and thorough analysis process. Evoked-responses (TBOAE and TBABR) were recorded from six normal hearing listeners for 17 different levels and seven frequencies (250, 500, 1000, 2000, 4000, 6000 and 8000 Hz). The recordings were analyzed and the results compared to two psychoacoustic procedures: Cross Modality Matching (CMM) and Magnitude Estimation (ME). Results for TBOAEs show agreement with results from previous studies for 1-kHz and 4-kHz and support the assumption that recorded signals at 500 and 2000 Hz are strong enough for such analysis, while analysis of signals at 250 and 8000 Hz are feasible but suffer from weak OAE response compromising the robustness. Recordings at 4000 and 6000 Hz were too contaminated to produce consistent results due to ear canal resonance. Results for TBABRs also show agreement with results from previous studies for 1-kHz and 4-kHz, and also exhibit consistency throughout the selected frequency range.