Summary Report on the Sixth International Congress on Noise as a Public Health Problem.

Although many of the papers at this congress were reiterations of previous work, or at least variations on the same theme, there were a number of new and exciting findings. Examples of these were the papers on the role of cochlear efferents in noise-induced hearing loss by the French researchers Pujol and Puel, the work of Al-Masri and his colleagues on underwater hearing thresholds, the work of Edworthy on warning signals, the sleep study by Ollerhead, and the Munich Airport study by Hygge et al. One cannot help but notice that the majority of the presentations, especially the most innovative and important ones, were given by non-U.S. researchers. This is also true of the activities in the international standards arena. It is quite clear that the United States has taken a back seat in noise effects research and regulation. Greater involvement and support by ASHA would be useful, but without federal government interest and support, the situation is unlikely to change.

Real-ear attenuation of earmuffs in normal-hearing and hearing-impaired individuals.

Many of the 9 million workers exposed to average noise levels of 85 dB (A) and above are required to wear hearing protection devices, and many of these workers have already developed noise-induced hearing impairments. There is some evidence in the literature that hearing-impaired users may not receive as much attenuation from hearing protectors as normal-hearing users. This study assessed real-ear attenuation at threshold for ten normal-hearing and ten hearing-impaired subjects using a set of David Clark 10A earmuffs. Testing procedures followed the specifications of ANSI S12.6-1984. The results showed that the hearing-impaired subjects received slightly more attenuation than the normal-hearing subjects at all frequencies, but these differences were not statistically significant. These results provide additional support to the finding that hearing protection devices are capable of providing as much attenuation to hearing-impaired users as they do to normal-hearing individuals.

Speech recognition in noise by individuals with mild hearing impairments.

The study was designed to test the validity of the American Academy of Ophthalmology and Otolaryngology's (AAOO) 26-dB average hearing threshold level at 500, 1000, and 2000 Hz as a predictor of hearing handicap. To investigate this criterion the performance of a normal-hearing group was compared with that of two groups, categorized according to the AAOO [Trans. Am. Acad. Ophthal. Otolaryng. 63, 236-238 (1959)] guidelines as having no handicap. The latter groups, however, had significant hearing losses in the frequencies above 2000 Hz. Mean hearing threshold levels for 3000, 4000, and 6000 Hz were 54 dB for group II and 63 dB for group III. Two kinds of speech stimuli were presented at an A-weighted sound level of 60 dB in quiet and in three different levels of noise. The resulting speech recognition scores were significantly lower for the hearing-impaired groups than for the normal-hearing group on both kinds of speech materials and in all three noise conditions. Mean scores for group III were significantly lower than those of the normal-hearing group, even in the quiet condition. Speech recognition scores showed significantly better correlation with hearing levels for frequency combinations including frequencies above 2000 Hz than for the 500-, 1000-, and 2000-Hz combination. On the basis of these results the author recommends that the 26-dB fence should be somewhat lower, and that frequencies above 2000 Hz should be included in any scheme for evaluating hearing handicap.