Binaural performance in 155 adults with single-sided or asymmetric profound hearing loss: A STROBE analysis

To estimate the proportion of subjects with single-sided or asymmetric profound hearing loss who achieve normal binaural performance, and to identify their specific demographic and audiological characteristics.

A French nationwide multicenter cross-sectional study included 155 subjects with single-sided or asymmetric profound hearing loss between 2014 and 2018. Speech-in-noise reception was assessed on the FraMatrix test in diotic, dichotic and reverse dichotic conditions to determine the signal-to-noise ratio allowing 50% correct reception. Sound localization was evaluated using a 180° 7-speaker horizontal array around the subject, to measure the root mean square error. The article was written following STROBE guidelines.

Nineteen of the 155 subjects with single-sided (n=104) or asymmetric profound hearing loss (n=51) achieved normal scores for diotic speech reception in noise (i.e., critical signal-to-noise ratio better than -4.8dB), and 9 subjects (7.1%) had normal sound localization (i.e.,<30° error). In the 44 subjects (28.4%) with normal or near-normal diotic signal-to-noise ratio (better than -3dB), had significantly better hearing thresholds in the better ear, and notably for high frequencies between 2 and 4kHz.

In this cross-sectional study, 7.1% to almost 30% of subjects with single-sided or asymmetric profound hearing loss showed normal or near-normal binaural performance. Their main distinguishing audiological feature was better hearing thresholds in the better ear, which suggests compensatory strategies based on monaural spectral cues.