Frequency Following Responses to Tone Glides: Effects of Age and Hearing Loss.

PURPOSE: Speech is characterized by dynamic acoustic cues that must be encoded by the auditory periphery, auditory nerve, and brainstem before they can be represented in the auditory cortex. The fidelity of these cues in the brainstem can be assessed with the frequency-following response (FFR). Data obtained from older adults-with normal or impaired hearing-were compared with previous results obtained from normal-hearing younger adults to evaluate the effects of age and hearing loss on the fidelity of FFRs to tone glides.

METHOD: A signal detection approach was used to model a threshold criterion to distinguish the FFR from baseline neural activity. The response strength and temporal coherence of the FFR to tone glides varying in direction (rising or falling) and extent ([Formula: see text], [Formula: see text], or 1 octave) were assessed by signal-to-noise ratio (SNR) and stimulus-response correlation coefficient (SRCC) in older adults with normal hearing and with hearing loss.

RESULTS: Significant group mean differences in both SNR and SRCC were noted-with poorer responses more frequently observed with increased age and hearing loss-but with considerable response variability among individuals within each group and substantial overlap among group distributions.

CONCLUSION: The overall distribution of FFRs across listeners and stimulus conditions suggests that observed group differences associated with age and hearing loss are influenced by a decreased likelihood of older and hearing-impaired individuals having a detectable FFR response and by lower average FFR fidelity among those older and hearing-impaired individuals who do have a detectable response.