Classrooms are often filled with deterrents that hamper a child's ability to listen and learn. It is evident that the acoustical environment in classrooms can be one such deterrent. Excessive background noise and reverberation can affect the achievement and educational performance of children with sensorineural hearing loss (SNHL) and children with normal hearing sensitivity who have other auditory learning difficulties, as well as elementary school children with no verbal or hearing disabilities. The purpose of this study was to evaluate the extent of the problem of noise and reverberation in schools. To that end, we measured reverberation times and background noise levels in 32 different unoccupied elementary classrooms in eight public school buildings in central Ohio. The results were compared with the limits recommended in the American National Standards Institute standard for acoustical characteristics of classrooms in the United States (ANSI S12.60-2002). These measurements were also compared to the external and internal criteria variables developed by Crandell, Smaldino, & Flexer (1995) to determine if a simple checklist can accurately predict unwanted classroom background noise levels and reverberation. Results indicated that most classrooms were not in compliance with ANSI noise and reverberation standards. Further, our results suggested that a checklist was not a good predictor of the noisier and more reverberant rooms.

Findings are described from three experiments that were designed to contrast estimates of auditory time and frequency analysis in highly practiced, young adult subjects having sensorineural hearing loss of cochlear origin with subjects having normal hearing. In one experiment, pure-tone detection threshold was measured for two durations of tones. For the hearing-impaired subjects, smaller differences were found between thresholds for the two durations of tones than were found for the normally hearing subjects at test frequencies where the sensitivity loss was greatest. In a subsequent forward masking experiment, masked thresholds were obtained at 3 kHz as a function of masker level at several masker durations. The results indicated that, for the range of values tested, masked probe thresholds changed less as a function of masker duration for the hearing-impaired subjects than for normally hearing subjects. However, forward masking grew as a function of masker level more steeply for the hearing-impaired listeners than for the normally hearing listeners. We believe that this result indicates abnormal temporal processing of sequential sounds. In a third experiment, psychophysical tuning curves were measured in a forward masking procedure for two maskers that differed in duration by approximately an order of magnitude. Again, the hearing-impaired subjects demonstrated less change in forward masking as a function of masker duration than normally hearing subjects. Further, the sharpness of the tuning curves from the hearing-impaired listeners was markedly reduced as compared to normal. It is believed that the results reflect a disruption of the normal temporal and spectral representation of sounds in the hearing-impaired subjects.

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The masking of one tone by a preceding tone (forward masking) was studied as a function of the duration of the masker. In general it was found that forward masking increased with increasing masker duration for the range of durations used (35 to 500 msec). The functions relating masked probe threshold in decibels to the logarithm of masker duration were well described by straight lines. The rate of growth of forward masking as a function of masker duration was greatest for relatively high masker levels and frequencies.

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