Abstract
Older adults often experience increased difficulties understanding speech in the presence of background noise, even in the absence of hearing impairment. This talk examines whether age-related declines in subcortical auditory processing can in part explain these speech in noise difficulties.
Recent animal work has suggested that ageing may lead to neural degeneration even in the absence of a permanent elevation in audiometric thresholds. This is often referred to as auditory neuropathy or hidden hearing loss. Auditory neuropathy is typically assessed non-invasively by measuring click-evoked auditory brainstem responses (ABR). It has been hypothesised that age-related neural degeneration may in part contribute to the increased speech in noise difficulties typically experienced by older adults. Furthermore, recent research has suggested an important role for neural coding at the level of the brainstem of more complex auditory stimuli such as speech, as measured by the frequency following response (FFR), for successful speech in noise perception.
Our data show that ageing is indeed associated with declines in subcortical auditory processing, as indicated by degradations of the ABR and FFR. Despite these declines, however, speech perception in steady-state and amplitude-modulated noise for our group of normal hearing older adults was not impaired. Moreover, declines in subcortical auditory processing could not explain the difficulties experienced by the older listeners in understanding speech in the presence of two-talker babble. Taken together these results show that declines in subcortical auditory processing do not necessarily lead to increased difficulties in the perception of speech in noise.