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Active Research
Clinical Applications For Time-compressed Speech Tests
Principal Investigators: Nancy Vaughan, Ph.D.
Objective: To determine whether diabetes-related cognitive deficits are associated with greater difficulty understanding speech in adverse listening conditions and whether an efficient speech recognition test known to be associated with cognitive deficits in older listeners can be used as an indicator of potential hearing aid benefit.
Background: The most common complaint of people with hearing loss is that speech is particularly difficult to understand in background noise, even with a hearing aid. One suggested reason for the reduced benefit of amplification is the limited ability of older listeners to benefit from cognitively demanding complex signal processing algorithms available in modern hearing aids. An efficient method of determining how individual cognitive status might affect potential hearing aid benefit would be an important clinical tool to facilitate appropriate selection of hearing aids. The interaction of working memory and hearing aid compression methods on speech recognition in three types of background competition for older listeners will be examined. The time-compressed speech (TCS) test, along with neurocognitive tests (WAIS-III Letter-Number Sequencing and the Digit Span subtests), two auditory temporal processing tests (the Auditory Fusion Test Revised and Duration Pattern Test), and the Hearing In Noise Test will be used in the three competing conditions for each of three types of amplification: one-channel linear, two-channel with fast time-compression constants and two-channel with slow time compression constants.
Findings: The compression system with fast time constants should improve the moment-to-moment audibility of speech masked by time-varying interference (modulated noise, single talker interference). The temporal distortions introduced by the fast compression system, however, increase the cognitive load on the listener and it is anticipated that only those listeners with relatively high cognitive capacity and good temporal resolution (as indicated by a high TCS test score) will benefit from this form of compression amplification. Listeners with low TCS scores are expected to benefit more from slow compression amplification. Further, for these listeners, the use of fast compression amplification may actually be detrimental to their ability to understand speech masked by time-varying interference.
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