Postoperatively, superior speech recognition ability in quiet and in noise for disyllabic words was achieved using bimodal stimulation in comparison to performance for either monaural aided condition. Mean improvement in speech recognition in the bimodal condition was significant over performance in the CI-alone condition for disyllabic words in quiet at 70 (p=0.006) and 55 dB SPL (p=0.028), for disyllabic words in noise at +10 dB with speech and noise spatially separated with the noise source closest to the contralateral HA (S0NHA) (p=0.0005) and when the noise source was closest to the CI ear (S0NCI) (p=0.002). When testing word recognition in noise with speech and noise sources coincident in space, word scores were superior in the bimodal condition relative to the CI-alone condition but this improvement was not significant (p=0.07). The advantages of bimodal stimulation included significant effects of binaural summation in quiet and significant binaural squelch effects in both the S0NHA and S0NCI test conditions. All subjects showed superior performance in the binaural situation postoperatively relative to the best-aided condition preoperatively for one or more test situations.

Recently the U.S. Food and Drug Administration approved the use of cochlear implants (CI) in patients with severe-to-profound sensorineural hearing loss with marginal benefit (< 30% speech discrimination) from hearing aids (HA). A multicentre trial was developed to determine whether this approval could be applied to the Spanish population. Nine postlingual adults from 3 centres were selected for the study. The mean preoperative unaided PTA threshold (0.25 to 4 KHz) was 108.6 dB HL for the poorer ear and 99.8 dB HL for the better. In all subjects the poorer ear was implanted with a Mini Nucleus 22 device. A single subject design study was used to compare performance with HA preoperatively and with CI postoperatively, or CI with contralateral HA. PTA measures and Spanish open set speech recognition tests were used. Comparing pre-implant levels with results after 6 months of CI use, all subjects improved significantly on all test measures: i) Mean aided soundfield threshold: 73.6 dB vs 39.8 dB ii) Mean bisyllabic recognition: 20% vs 57% iii) Mean consonant discrimination: 20% vs 49% iv) Mean CID sentences: 22% vs 73%. Five subjects discontinued use of the contralateral HA after implantation, three continued occasionally to use the HA, and one continued to use both on a full-time basis. Patients performed significantly better post-implant on speech recognition compared with their best pre-implant HA scores. Therefore the CI appears an appropriate treatment for Spanish speakers with a severe-to-profound hearing loss and marginal benefits with HA.

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