Introduction:
Previous work using speech evoked ABR reported a significant decline in onset and offset responses with advancing age, but no differences for Frequency Following Responses (FFRs). Many researchers report reduced neural synchrony as age advances. The aim of this study was to investigate the effect of aging on FFRs.

Material and methods:
A total of 45 participants were included in the study. They were divided into three groups of 15 individuals: young adults (20–40 years), middle aged adults (41–60 years), and older adults (>60 years). All had normal hearing sensitivity and were free from any otologic or neurologic disorder. FFRs were obtained using a /da/ stimulus of 40 ms and 80 dBnHL containing five formants. To minimize preferential recording of activity from either side, a midline electrode site was used. Data analysis followed Russo et al. [1]. The seven peaks of the response to /da/ (waves V, A, C, D, E, F, O) were identified by two experienced audiologists as onset responses, spectro-temporal responses, fundamental frequency, and harmonics.

Results:
Findings were that the occurrence of waves V and A was 100% in all individuals, but the occurrence of waves C and O was 60% in young adults, 73% in middle age adults, and 53% in older adults.

Conclusions:
These findings suggest that older listeners have a general reduction in synchronous neural firing to speech stimuli. In particular, the ability of neurons in the auditory system to accurately encode important temporal features of speech may in older adults be limited by impaired neural synchrony, slowed neural conduction time, reduced phase locking ability, or other mechanisms.