Speech intelligibility in difficult signal/noise circumstances.
In practice, subjects wearing ear protectors often give contradictory statements about the possible distorting effects of ear protectors. We tried to simulate some difficult background circumstances by arranging five different signal/background noise combinations (five S/N ratios). Speech discrimination tests made in these circumstances with and without ear protectors could reflect the real capacity to understand orders or messages in difficult hearing situations. 52 Finnish speaking conscripts with normal hearing from 18 to 24 years age were selected to participate in the test on a day without any noisy training duties. The test words in the Finnish speech discrimination test in combination with corresponding white noise were produced by equipment consisting of a high quality tape recorder, an audiometer, an amplifier and loud speakers. The test were performed individually in free field in a sound proof room in the Hearing Centre of the University Central Hospital of Oulu. The subjects listened to the test words with all the S/N ratios [S/N = 60/70, 55/70, 65/70, 60/75 and 65/75 dB (A)] with and without ear protectors. At the signal/noise ratios 60/70 and 60/75 dB the words were perceived relatively poorly with and without hearing protectors. At the signal/noise levels of 65/70 and 65/75 dB the protectors turned out to produce highly significantly better word discrimination. At the signal/noise level of 55/70 dB the discrimination is very poor in both cases but significantly better without ear protectors.
Kiukaanniemi
H
H
ENT-Clinic, Military Hospital, Oulu, Finland.
Sorri
M
M
D000328:Adult; D004430:Ear Protective Devices; D006801:Humans; D008297:Male; D008889:Military Personnel; D009622:Noise; D011482:Protective Devices; D013065:Speech Intelligibility