Effect of time scale modification of speech on the speech recognition threshold in noise for elderly listeners

The effect of time scale modification of speech on the speech recognition threshold in noise (SRTN) was investigated for a group of 44 elderly subjects, varying in age from 56 to 88 years with sloping mild-to-moderate sensorineural hearing losses. Subjects' pure-tone average thresholds at 500, 1,000 and 2,000 Hz (PTA1) ranged from 3 to 58 dB. The study confirms the well-known fact that speech recognition in noise deteriorates with increasing age. Furthermore, time-compressing speech results in an even greater influence of age on the SRTN. The apparent age effect on SRTN values referenced to SRTN in the control condition is mostly caused indirectly by the significant correlation between age and PTA1, although there was a slight tendency for age to have a greater independent effect on relative SRTN values when the amount of time compression increased. The percentage of explained variance in relative SRTN values by the subject variables in this study was limited, indicating that there are other factors not investigated in this study (e.g. cochlear mechanisms, short-term memory, feature extractors) that significantly influence the effect of time compression on SRTN.