Effects of context on time-compressed speech intelligibility in older adults

Abstract

The purpose of this study was to assess the effects of context on sentence intelligibility at high compression rates in older adults. A group of older participants listened to time-compressed low-predictability sentences from the SPIN-R test and high-context sentences from the Connected Speech Test (CST). Many studies have shown that speech intelligibility declines significantly at a 60% compression rate especially for older adults. An algorithm called the Synchronized Overlap Add (SOLA) has been shown to produce intelligibility scores above 80% on the CST for adults aged 65–75 years at 60% compression. This method uses an autocorrelation function to combine common elements in overlapping sequential frames of the speech signal, producing highly intelligible speech at high rates of compression. An apparently similar algorithm used in another study of older adults produced intelligibility scores around 50% for the low-predictability sentences of the SPIN-R test at a 60% compression rate. The question of whether the varying results of time-compressed speech intelligibility was due to differences in algorithms or to differences in context of the speech materials remains unanswered. The results of the current study are discussed in terms of speaker gender, context, and methods of time-compression.