Binaural squelch effect in unilateral otosclerosis surgery: comparison of speech intelligibility in noise before-after surgery.

Abstract

We aimed to evaluate the speech intelligibility benefit in noise provided by stapedotomy in the treatment of unilateral otosclerosis. We enrolled adults suffering from unilateral conductive hearing loss and followed them up until 9months after surgery. The patients underwent a free field speech hearing evaluation using the French Matrix test before and after stapedotomy. Speech material was sent to the front of the patients (S0) and noise was presented either at the front (N0), or at the operated ear (N-90) or at the non-operated ear (N + 90). The speech intelligibility benefit in noise was assessed by comparing Squelch effect (SE), Head shadow effect (HS) and Binaural redundancy (BR) before and after surgery. SE was measured as the difference in speech reception thresholds (SRT) between S0N + 90 situations before and after surgery, HS as the difference in SRT between S0N + 90 and S0N-90 situations, and BR as the difference in SRT between S0N0 situations before and after surgery. In addition, two quality of life's questionnaires were completed by patients to evaluate their discomfort. Among 25 patients, 19 were followed up during 9months, 4 were excluded and 2 were lost for the following-up. Stapedotomy provided a restoration of SE of 3.7dB SNR (p < 0.001) and a BR gain of 1.8dB SNR (p < 0.001). HS did not show any statistical variation after surgery (p = 0.077). Finally, the questionnaires showed a residual hearing discomfort. Stapedotomy provided a binaural benefit with the restoration of the SE and BR but which remained lower than in the normal-hearing population. The 07/02/2018 on Clinical.Trial.Gouv: NCT03587792.