Cochlear Implant Sound Quality

The aims of this exploratory study were (a) to assess common terms used to describe cochlear implant (CI) sound quality by patients fit with conventional CIs and (b) to compare those descriptors to previously obtained acoustic matches to CI sound quality created by single-sided deaf (SSD) patients for their normal-hearing ear.

CI patients fit with Advanced Bionics (AB; n = 89), Cochlear Corporation (n = 86), and MED-EL (n = 80) implants were the participants. The patients filled out a questionnaire about CI sound quality for two time points: For the time near activation (T1) from memory and at the time of filling out the questionnaire (T2). The mean CI experience at T2 for the three groups ranged from 4 to 8 years. The questionnaire was composed of 25 adjectives describing sound quality.

For T1, the most commonly used descriptors were Computer-like, Treble-y, Metallic, and Mickey Mouse-like. A superordinate category of HiPitched (High Pitched) gathered significantly more responses from patients with shorter electrode arrays (AB and Cochlear) than patients with longer arrays (MED-EL). At T2, the most common descriptor was Clear and was chosen by approximately two thirds of the patients. The between-group differences in responses to items in the HiPitched category, present at T1, were absent at T2.

The questionnaire data from conventional CI patients differs from previous sound matching data collected from SSD-CI patients. Alterations to the spectral composition of the signal are less salient to experienced conventional patients than to experienced SSD-CI patients. This is likely due to the absence, for conventional patients, of an exemplar in an NH ear against which to judge CI sound quality.