An across-frequency processing deficit in listeners with hearing impairment is supported by acoustic correlation

It has been recently suggested that listeners having a sensorineural hearing impairment (HI) may possess a deficit in their ability to integrate speech information across different frequencies. When presented with a task that required across-frequency integration of speech patterns, listeners with HI performed more poorly than their normal-hearing (NH) counterparts (E. W. Healy & S. P. Bacon, 2002; C. W. Turner, S.-L. Chi, & S. Flock, 1999). E. W. Healy and S. P. Bacon (2002) also showed that performance of the listeners with HI fell more steeply when increasing amounts of temporal asynchrony were introduced to the pair of widely separated patterns. In the current study, the correlations between the fluctuating envelopes of the acoustic stimuli were calculated, both when the patterns were aligned and at various between-band asynchronies. It was found that the rate at which acoustic correlation fell as a function of asynchrony closely matched the rate at which intelligibility fell for the NH listeners. However, the intelligibility scores produced by the listeners with HI fell more steeply than the acoustic analysis would suggest. Thus, these data provide additional support for the hypothesis that individuals having sensorineural HI may have a deficit in their ability to integrate speech information present at different frequencies.