Using the Callsign Acquisition Test (CAT) to investigate the impact of background noise, gender, and bone vibrator location on the intelligibility of bone-conducted speech

Traditionally, combat operations have relied on air-conducted radio communication to receive and transmit information. Recently, however, there has been the need to find alternatives because headphones used in air conduction are bulky and cover the ears of the listener, thus reducing the listener's awareness of his/her surroundings. Bone-conducted radio communication, however, uses lightweight and inconspicuous transducers which allow radio communication without compromising the listener's awareness of his/her surroundings. This research investigated the intelligibility of bone-conducted speech in white, pink, babble and quiet background environments at the condyle and mastoid locations on the head using the Callsign Acquisition Test (CAT). Data were collected and analyzed from 20 normal hearing participants (10 males and 10 females) between the ages of 19 and 31 years. Significant interaction effect between gender and background noise was found from the results. Post-hoc analysis showed that for both males and females, background noise had a significant impact on speech intelligibility. In babble background, there was a significant difference in speech intelligibility between the male and female listeners (males performed better than females). However, no significant effects were found for the other type of background noises. The results also indicated that there was no statistically significant difference in intelligibility scores between the condyle and mastoid locations. This study investigated the impact of background noise, gender of listener, and location of bone vibrator on the intelligibility of bone-conducted speech. Findings of this study revealed the impact of different background environments and listener's gender on speech intelligibility and will assist in the development of improved bone conduction devices in the future.