Effects of interferer facing orientation on speech perception by normal-hearing and hearing-impaired listeners

There exist perceptible differences between sound emanating from a talker who faces and a talker who does not face a listener: Sound from a non-facing talker is attenuated and acquires a spectral tilt. The present study assessed the role that these facing-orientation cues play for speech perception. Digit identification for a frontal target talker in the presence of two spatially separated interfering talkers was measured for 10 normal-hearing (NH) and 11 hearing-impaired (HI) listeners. Overall-level differences and spectral tilts were reproduced by means of digital filtering and playback via loudspeakers. Both NH and HI listeners performed significantly better when the interfering talkers were simulated not to be facing them. Spectral tilts and level differences across talkers reduced target-interferer confusions. They enabled the NH listeners to sequentially stream the digits. This was not the case for the HI listeners, who showed smaller benefits, irrespective of whether they were aided by their own hearing aids or not. While hearing-aid amplification increased audibility, it may not have aided target-interferer segregation or target selection. The present results suggest that facing orientation cannot be neglected in the exploration of speech perception in multitalker situations.