Factors constraining the benefit to speech understanding of combining information from low-frequency hearing and a cochlear implant.

In this study we assessed the role of three factors in determining the magnitude of bimodal benefit -- (i) the level of CI-only performance, (ii) the magnitude of the hearing loss in the ear with low-frequency acoustic hearing and (iii) the type of test material. The patients had low-frequency PTAs (average of 125, 250 and 500 Hz) varying over a large range (<30 dB HL to >70 dB HL) in the ear contralateral to the implant. The patients were tested with (i) CNC words presented in quiet (n=105) (ii) AzBio sentences presented in quiet (n=102), (iii) AzBio sentences in noise at +10 dB signal-to-noise ratio (SNR) (n=69), and (iv) AzBio sentences at +5 dB SNR (n=64). We find maximum bimodal benefit when (i) CI scores are less than 60 percent correct, (ii) hearing loss is less than 60 dB HL in low-frequencies and (iii) the test material is sentences presented against a noise background. When these criteria are met, some bimodal patients can gain 40-60 percentage points in performance relative to performance with a CI.
PMID: 25285624 [PubMed - as supplied by publisher]

Source: Hearing Research - October 3, 2014 Category: Audiology Authors: Dorman MF, Cook S, Spahr T, Zhang T, Loiselle L, Schramm D, Whittingham J, Gifford R Tags: Hear Res Source Type: research