Relationships between listening skills and the brainstem response to speech in individuals at-risk for Central Auditory Processing Disorder

People with difficulties in processing auditory information are part of a heterogeneous group with multiple underlying and interconnected deficits. Difficulty processing speech in noise can result from, expressive and receptive language deficits, attention deficits, auditory processing deficits, and sensory integration deficits. Individuals who exhibit these problems are not always identified with typical tests of auditory processing. The speech-evoked, complex Auditory Brainstem Response (cABR), appears to be a promising “non-traditional” method to test this hypothesis because ample research has shown it to be an objective and reliable measure of encoding deficits in quiet and background noise. Additionally, the Auditory Processing Domains Questionnaire (APDQ) has recently been developed and validated to differentiate between populations with underlying problems of processing speech in the background noise. In the current study, we administered these two tests, in addition to standard tests, to 19 individuals who were referred for CAPD assessment. Our results showed that lower APDQ scores were correlated with delayed brainstem response latencies and weaker encoding of the speech fundamental frequency in noise. Individuals who had below average brainstem response measures performed 20-30% worse on Auditory Processing and Language portions of the APDQ than those with above average brainstem responses. Brainstem responses did not differ between CAPD+ and CAPD- groups and APDQ scores were significantly lower in the CAPD+ group, however no difference was observed between CAPD+/- groups on the standard protocol tests. This suggests that a subset of individuals who struggle with auditory information have concurrent deficits encoding speech sounds, especially in noise. People who have these difficulties may be missed by current evaluative methods. The data presented here suggest that electrophysiological tests of neuronal synchrony can assist in understanding the deficit diaspora of an individual at-risk for CAPD