Artificial Robot Ear Design for Sound Direction Estimation

We propose a novel design of artificial robot ear for sound direction estimation using measured two outputs only. The spectral features in head-related transfer functions and in interaural transfer functions (ITFs) are distinctive in the voice frequency band. Thus, these features provide effective sound cues to estimate the sound direction using two measured ear outputs only without input information. Especially, the direction of median source can be estimated by the bilateral asymmetry of microphone positions, whereas many previous studies, which depend on the interaural differences, cannot achieve. We propose a localization method to estimate the lateral and vertical angles simultaneously. The lateral angle is estimated using interaural time delay and Woodworth and Schlosberg's formula, and the front-back discrimination is achieved by the presence of the spectral features in ITF estimated from two measured outputs. The vertical angle of the frontal source is estimated by comparing the spectral features in the estimated ITF with those in the database built in an anechoic chamber.