Noise levels that are tolerable when listening to speech

It is known that speech understanding declines with increased background noise. It is unknown, however, what noise levels are tolerated by individuals when they are listening to speech. A story recorded by a female was played through an earphone at a comfortable level. A noise was added and the subject was asked to set the noise level at the highest level that would not exceed tolerable listening conditions. The interferences were (1) a babble of 12 voices, (2) speech spectrum-shaped noise, (3) traffic noise, (4) music in a Muzak style, and (5) noise from a pneumatic drill. The subjects were (1) young adults with normal hearing, (2) elderly (at least 65 yr of age) with essentially normal hearing, (3) elderly who were successful hearing aid users, and (4) elderly who rejected their hearing aids. The following results will be discussed: (1) differences between young and elderly subjects, (2) differences among noises, and (3) differences between successful and unsuccessful hearing aid users. [Research supported by AARP Andrus Foundation.]