Representation of speech in noise in the aging midbrain and cortex: aging may dominate over hearing-loss

ObjectiveTo understand the effect of peripheral hearing loss on the representation of speech in noise in the aging midbrain and cortex.\n\nMethodsSubjects comprised 17 normal-hearing younger adults, 15 normal-hearing older adults and 14 hearing-impaired older adults. The midbrain response, measured with Frequency-Following Responses (FFRs), and the cortical response, measured with magnetoencephalography (MEG) responses, were recorded from subjects listening to speech in quiet and noise at varying signal to noise ratios (SNRs).\n\nResultsBoth groups of older listeners showed both weaker midbrain response amplitudes and overrepresentation of cortical responses compared to younger listeners. However, significant differences between the older groups were found in both midbrain-cortex relationships and in cortical processing durations, suggesting that hearing loss may alter reciprocal connections between lower and higher levels of the auditory pathway.\n\nConclusionsThe paucity of differences in midbrain or cortical responses between the two older groups suggest that age-related temporal processing deficits may contribute to older adults communication difficulties beyond what might be predicted from peripheral hearing loss alone.\n\nSignificanceClinical devices, such as hearing aids, should not ignore age-related temporal processing deficits in the design of algorithms to maximize user benefit.\n\nHIGHLIGHTSO_LIMild sensorineural hearing loss does not appear to significantly exacerbate already appreciable age-related deficits in midbrain speech-in-noise encoding.\nC_LIO_LIMild sensorineural hearing loss also does not appear to significantly exacerbate already appreciable age-related deficits in most measures of cortical speech-in-noise encoding.\nC_LIO_LICentral processing deficits caused by peripheral hearing loss in older adults are seen only in more subtle measures, including altered relationships between midbrain and cortex.\nC_LI