Supra-threshold envelope-following responses in the ageing population: An early marker of sensorineural hearing damage

Abstract

Envelope-following-responses (EFRs) evoked by supra-threshold amplitude-modulated sounds are promising markers of age-related or ototoxic-induced cochlear synaptopathy (CS) in research animals. A direct translation of these findings to EFR-based CS-quantification in humans is complicated by possible combinations of CS, inner-, outer-hair-cell damage or central deficits that can also affect EFR markers. To work towards a sensitive CS-marker for use in humans, we focus on an EFR stimulus that—in computational model simulations—is maximally sensitive to CS and investigate how this marker declines in an ageing population with or without OHC damage. 108 subjects participated in this study and were divided into two groups: (i) an ageing group with normal audiograms (i.e., 4-kHz-thresholds <20 dB HL, n = 89, 18–65 years) and (ii) older adults with impaired audiograms (n = 19, 45–75 years). We collected 120-Hz modulated EFRs, along with extended high-frequency audiograms, distortion-product otoacoustic emissions, and speech-reception thresholds (Flemish Matrix test). We calculated the rate of decline of each metric with age and conclude that the EFR marker predicts sensorineural hearing damage approximately 10 years earlier than the standard clinical audiogram. Additional relationships between audiometric, speech-intelligibility, and EFR markers are discussed. [Work supported by ERC 678120 RobSpear and 899858 CochSyn.]