Speech intelligibility in noise: effects of fluency and hearing protector type

This research investigated the effect of car protectors on the intelligibility of speech in noise. Listeners with normal hearing, high-frequency, and flat loss were tested. Half the subjects in each group were fluent in English and half-poorly conversant. Taped lists of 25 words were presented free field under conditions defined by the speech-to-noise ratio, spectrum of noise background, and presence of ear protection. The results showed that intelligibility decreased with speech-to-noise ratio and was poorer in crowd noise than in white noise. The protector had no effect for the normal listener, but caused a substantial decrement in those with impairment. In all groups nonfluency contributed an additional loss of 10% to 20%. Significant differences in performance were noted for different muff and plug types.