Abstract

OBJECTIVE: The objective of this study was to evaluate the degree of intelligible speech in workers wearing hearing protective devices and the differences in background noise type.
METHODS
A total 82 shipyard company employees and normal hearing volunteers were recruited as subjects from a company in Ulsan: subjects were classified to the hearing-impaired group or to the control group according to hearing status. They were tested pure tone and speech audiometry in varying test environments including signal-to-noise ratio and background noise type in a headphone and in a free field environment.
RESULTS
For both groups, the attenuation of hearing protective devices was greater at high frequencies. For the hearing-impaired group, speech discrimination scores differences between the unprotected and the protected ear were not significant between background noise type, when speech was presented at 65 dBA. However speech intelligibility in white noise background was lower than in the other background noise types when speech was presented at 75 dBA.
CONCLUSIONS
Workers' speech intelligibility increased with an increasing signal-to-noise ratio. Speech intelligibility was also dependent on background noise type. Workers and their colleagues were trained to pronounce words more loudly and more clearly when they wearing hearing protective devices or other communication methods that do not use sound signal should be considered.

• Keywords: Speech intelligibility;Noise;Hearing protective devices