Effects of number of channels on speech perception with tactile aids

Abstract

Although there is considerable evidence that multichannel tactile aids for the hearing impaired provide more information about the speech signal to the wearer than do single‐channel tactile aids, it has not been determined how many channels are necessary for optimal transmission of speech information. In the present study, the 5‐channel Tactaid V (Audiological Engineering Corporation) and the 16‐channel Queen's University tactile vocoder were evaluated in a series of phoneme identification and connected speech tasks, to determine whether the additional channels present in the 16‐channel design lead to better speech perception performance. Results showed that, in relatively simple tasks, such as minimal pairs phoneme discrimination, subjects performed at similar levels with both devices. However, in more complex tasks, such as integration with lipreading, the 16‐channel device yielded significantly higher levels of performance. In connected discourse tracking, both devices showed significantly higher levels of performance in conjunction with lipreading than were found under lipreading alone conditions. Results are discussed with respect to the benefits provided by a tactile aid relative to the practical limitations of tactile aids that employ a large number of tactile transducers. [Work supported by NIH and NSF.]