Audiometric results of the Bone Conduction Implant: a comparative study with the Bone Anchored Hearing Aid
Patients suffering from conductive-, sensorineural- or mixed hearing loss that are unable to use conventional air conduction hearing aids, can often be rehabilitated with bone conduction devices (BCDs) . The most widely used BCD is the percutaneous Bone Anchored Hearing Aid (BAHA), which gives excellent sound but has some known complications related to the side effects from the skin penetration. In order to overcome such issues, the development of transcutaneous BCDs has increased. Among them, the Bone Conduction Implant (BCI) is an active BCD developed in Gothenburg, Sweden. It comprises an externally worn audio processor unit which is magnetically attached to an implanted unit to wirelessly drive a transducer in the temporal bone. The device is currently implanted in six patients in the clinical trial phase and the objective with this study is to compare the BCI and BAHA devices.
Audiometric measurements are currently carried out on BCI and BAHA patients matched one by one according to age- and hearing loss-based criteria. In particular, pure tones hearing thresholds, speech recognition threshold (SRT) in quiet and speech recognition score (SRS) in noise are compared as well as signal to noise ratio (SNR). In addition, maximum power output (MPO) and total harmonic distortion (THD) are measured for each device on a skullsimulator in an anechoic chamber. The patients’ satisfaction and general health condition are also evaluated by means of questionnaires.
Results from three patients tested with the BAHA indicate that they generally perform as or slightly worse than matched patients with BCI in all tested audiometric measurements. The self-reported questionnaires show in general similar outcome for both devices, with slightly better results for BCI compared with the BAHA concerning physical benefit and avoidance of negative reactions to unpleasant sounds.
Results from audiometric measurements show a clear improvement over the unaided condition for both devices, and indicate that the BCI is equal or slightly better than the BAHA. As this is a pilot study currently ongoing, the results may change when all six BCI patients have been matched with a BAHA patient.