gms | German Medical Science

In a study, twenty-five adult patients who had been bimodally fitted were monitored for one year, with both directional hearing and speech understanding in noise being tested. Tests were performed with a hearing aid alone, with a CI alone and with bimodal fitting. For the directional hearing test, 12 loudspeakers were placed in a circle. Speech understanding in noise was tested using the HSM sentence test (SNR+10dB in different conditions).

Bimodal fitting is superior to unilateral cochlear implantation. Although the different devices gave rise to differences in hearing sensation, bimodally fitted individuals were shown to have superior directional hearing. Patients with bimodal fitting also achieved better speech understanding in noise (63,9% vs.46,5%). Comparison with bilaterally fitted patients revealed a similar outcome with regard to speech understanding in quiet after one year (70,8% vs. 62,3%). As these recipients have a long history of preoperative hearing aid experience, the development of speech understanding in noise over the first few months is better in bimodally fitted patients if the speech and the noise came from the same direction (64,3% vs.41,1%). When the speech was separated from noise the bimodal group show similar results in noise as the bilateral group (Squelch: about 15%).

Provided that, in combination, residual hearing and the hearing aid make adequate speech understanding achievable, bimodal fitting is clearly superior to unilateral cochlear implantation. There is a significant difference in speech understanding in quiet and noise between unilateral and bimodal supply.