The Effect of Gel Application on the Transducer in Cartilage Conduction Hearing Aids: A Case Series Study

In ultrasonography, gels are used as conduction media to improve sound transmission and to obtain high-quality images; however, gels are rarely used in hearing devices. The application of gel to couple the transducer to the ear could potentially improve the benefits of hearing aids, particularly cartilage conduction (CC) hearing aids, which deliver sound through vibrating the aural cartilage. This study aimed to investigate the effects of gel application on the performance of CC hearing aids.

Twenty-three patients (30 ears) with aural atresia or severe canal stenosis were treated with CC hearing aids. The aided thresholds, maximum speech recognition scores (SRSs), and hearing levels at which the maximum SRS (dB [Max]) was observed were compared before and after gel application to the transducer of the CC hearing aids.

Thresholds > 1 kHz significantly decreased (improved) when the gel was applied to the transducer (p < 0.05). The threshold improvement at 1 kHz was significantly better than that at 0.5 kHz, and that at 4 kHz was significantly better than at 0.25 and 0.5 kHz. No significant differences were observed in the maximum SRS or dB (Max).

Gel application, which is considered to have minimum risk, showed statistically significant improvements in hearing levels at higher frequencies. Therefore, the application of gel can be considered a beneficial option to enhance the performance of CC hearing aids by improving the coupling conditions.

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