Early Deficits in Speech Perception in Carriers of the p.Pro51Ser Variant in the COCH Gene: A Prospective Longitudinal Evaluation of Speech Perception in Quiet and Noise.

Abstract

Background and aim: The primary concern among adults with regard to their hearing is the difficulty in comprehending speech, particularly in noisy environments. The constant need to listen attentively leads to heightened frustration, fatigue, and decreased concentration. According to research, high-frequency hearing loss could have negative implications on speech perception and make it even harder to communicate. In this study, the focus is on patients with DFNA9 as it is one of the most common forms of non-syndromic high-frequency hearing loss. These patients carry the p.Pro51Ser variant in the COCH gene, which leads to progressive decline of hearing and vestibular function. Despite various cross-sectional studies on the natural progression of hearing levels, speech perception in silence and noisy surroundings is largely unexplored in this group of patients.

Method: For the longitudinal analysis of speech perception, 101 heterozygous carriers of the p.Pro51Ser variant in the COCH gene were enrolled. In addition, a control group composed of individuals with normal hearing, who matched the patients with DFNA9 in the study in terms of age and sex, was recruited. All patients underwent pure-tone audiometry, speech perception in quiet (SPIQ), and speech perception in noise (SPIN).

Results: The SPIQ outcomes reveal a mean speech reception threshold (SRT) of 28.18 dB SPL for male carriers and 29.29 dB SPL for female carriers in the youngest age-group (18-29 years). With increasing age, a steep decrease was noticed, and no speech discrimination ability in quiet remained for carriers in their seventh decade. Differences between carriers and control participants seem evident in the third decade of life and become more pronounced in the decades that follow. The SPIN displayed a similar trend, varying from -5 dB SNR in the youngest age-group, to no speech-in-noise thresholds in patients above the age of 60 years. In contrast, the matched group exhibited a SRT range from -5.5 to -3.25 dB SNR for males, and from -6.23 to -4.58 dB SNR for females from the second/third to the seventh decade. This stands in contrast to the DFNA9 population, where male carriers reach values of -5.18 dB SNR and female carriers reach -3.12 dB SNR as early as in the fourth decade.

Conclusion: This study indicates poor performance on speech understanding in quiet and noise in DFNA9 patients in comparison with the group with normal hearing, even at a young age. Therefore, future research should not only investigate pure-tone audiometry, but also speech perception. Moreover, reimbursing hearing aids based on speech-in-noise testing could prove to be more advantageous than based on pure-tone audiometry.