Speaking Clearly for Older Adults With Normal Hearing: The Role of Speaking Rate

Purpose: Talkers typically use a slow speaking rate when producing clear speech, a speaking style that has been widely shown to improve intelligibility over conversational speech in difficult communication environments. With training, however, talkers can learn to produce a form of clear speech at normal speaking rates that provides young listeners with normal hearing much of the same intelligibility benefit. The purpose of this study was to determine if older listeners with normal hearing can also obtain an intelligibility benefit from clear speech at normal rates. Method: Eight older listeners (55-68 years of age) with normal hearing were presented with nonsense sentences from 4 talkers in a background of speech-shaped noise (signal-to-noise ratio = 0 dB). Intelligibility (percent correct key words) was evaluated for conversational and clear speech produced at 2 speaking rates (normal and slow), for a total of 4 conditions: cony/normal, cony/slow, clear/normal, and clear/slow. Results: As expected, the clear/slow speaking condition provided a large and robust intelligibility advantage (23 points) over cony/normal speech. The cony/slow condition provided almost as much benefit on average (21 points) but was highly variable across talkers. Notably, the clear/normal speaking condition provided the same size intelligibility advantage (14 points), previously reported for young listeners with normal hearing (Krause & Braida, 2002), thus extending the benefit of clear speech at normal speaking rates to older normal-hearing listeners. Conclusions: Applications based on clear/normal speech (e.g., signal processing approaches for hearing aids) have the potential to provide comparable intelligibility improvements to older and younger listeners alike.