Effects of hearing loss and language proficiency on speech intelligibility over radio transmission with tactical communication devices

Objective: Study the effects of hearing loss and language proficiency in a speech task over radio transmission. Design: Four TCAPS device conditions (2 models x 2 talk-through modes) were investigated with the Modified Rhyme Test (MRT) conducted in talker-listener pairs immersed in 85-dBA noise. Speech quality ratings and preferred radio volume levels were also collected. Study sample: Thirty-six participants divided into three groups (control, non-fluent, hearing-impaired) took part in the experiment. Participants acted as talkers and listeners when paired with a unique standard individual (fluent and normal hearing) of the same gender. Results: MRT scores were significantly lower in many device conditions when the non-fluent group of participants acted as listeners and talkers and when the hearing-impaired participants acted as listeners, compared to the control group. MRT results were also consistently poorer with one device configured for bone-conducted voice pick-up in the occluded ear compared to another one equipped with an external mouth microphone. Talk-through settings had little effect. MRT results were reflected in the subjective quality ratings. Participants with hearing loss used higher radio volume levels. Conclusions: Language proficiency, hearing loss and method of sensing the talker's voice are key issues to consider with TCAPS devices.