A Systematic Review of the Literature Between 2009 and 2019 to Identify and Evaluate Publications on the Effects of Age-Related Hearing Loss on Speech Processing.

Changes in central auditory processing due to aging in normal-hearing elderly patients, as well as age-related hearing loss, are often associated with difficulties in speech processing, especially in unfavorable acoustic environments. Speech processing depends on the perception of temporal and spectral features, and for this reason can be assessed by recordings of phase-locked neural activity when synchronized to transient and periodic sound stimuli frequency-following responses (FFRs). An electronic search of the PubMed and Web of Science databases was carried out in July 2019. Studies that evaluated the effects of age-related hearing loss on components of FFRs were included. Studies that were not in English, studies performed on animals, studies with cochlear implant users, literature reviews, letters to the editor, and case studies were excluded. Our search yielded 6 studies, each of which included 30 to 94 subjects aged between 18 and 80 years. Latency increases and significant amplitude reduction of the onset, offset, and sloop V/A components of FFRs were observed. Latency and amplitude impairment of the fundamental frequency, first formant, and high formants were related to peripheral sensorineural hearing loss in the elderly population. Conclusions: Temporal changes in FFR tracing were related to the aging process. Hearing loss also impacts the envelope fine structure, producing poorer speech comprehension in noisy environments. More research is needed to understand aspects related to hearing loss and cognitive aspects common to the elderly.