Speech communication in lecture halls and classrooms for hearing-impaired

Abstract

Rooms with good acoustics for normal-hearing listeners might be inadequate for people with hearing impairments. To achieve listening conditions satisfactory for the hearing-impaired listeners, three conditions must be met: (1) Speech should be delivered at higher sound-pressure level than for normal-hearing listeners to compensate for hearing loss; (2) background noise should be at least 15 dB lower than the level of speech; and (3) the reverberation time of the room should be as short as possible. Amplification through public address systems is not practical because hearing-impaired listeners would need levels not tolerated by the general public. Also, because there are limits to reduction in background noise and elimination of sound reflections, listening conditions in lecture halls and in classrooms might be less than ideal for the hearing-impaired. A solution is the use of assistive listening systems. In these systems, sounds which are picked up by microphones located close to the talkers' mouths contain little noise and reverberation. Then the sounds are transmitted on radio or infrared waves throughout a whole room. The sounds are received by individually worn receivers which are equipped with gain controls. The benefits and limitations of assistive listening systems will be discussed. [Work supported by NIH.]