The Relationship between Binaural Hearing and Speech-in-Noise Performance in Middle-Aged Listeners

Binaural hearing supports perceptual segregation of sound sources based on interaural timing cues and is a key contributor to speech-in-noise (SIN) performance. Recent evidence indicates that neural representation of binaural timing cues begins to decline as early as 40-60 years old, suggesting that the parallel emergence of SIN complaints in middle-age may be related to reduced binaural processing. Despite a large literature describing behavioral binaural hearing tests and an increasing awareness that tests of binaural function may be sensitive to changes in temporal acuity that are not identified by the standard audiogram, no widely accepted clinical measure of binaural hearing function is currently available. An objective test of binaural hearing function would offer clinical utility in assessing the nature of SIN deficits as well as verifying and fine-tuning binaural hearing aid and cochlear implant fittings. The broad goals of this research are to 1) develop objective indices of binaural hearing acuity and 2) investigate relationships between these indices and SIN performance. To achieve these goals, we will use a comprehensive test battery including auditory evoked potentials to examine neural processing of binaural timing cues to simple (tones) and complex (speech) stimuli in middle-aged adults. Further, we will relate these measures to SIN perceptual performance on tests requiring binaural hearing. We predict that the strength of neural binaural timing cues to simple and complex stimuli will be positively correlated with SIN performance. This proposal is unique in that the principal investigator has extensive research (Ph.D.) and clinical audiology (Au.D.) training. With help from his mentor (Kraus) and other key personnel, this translational research is poised to make a significant impact on clinical practice.