Self-Adjustment of Upper Electrical Stimulation Levels in CI Programming and the Effect on Auditory Functioning.

Abstract

With current cochlear implants (CIs), CI recipients achieve good speech perception in quiet surroundings. However, in acoustically complex, real-life environments, speech comprehension remains difficult and sound quality often remains poor. It is, therefore, a challenge to program CIs for such environments in a clinic. The CI manufacturer Cochlear Ltd. recently introduced a remote control that enables CI recipients to alter the upper stimulation levels of their user programs themselves. In this concept, called remote assistant fitting (RAF), bass and treble controls can be adjusted by applying a tilt to emphasize either the low- or high-frequency C-levels, respectively. This concept of self-programming may be able to overcome limitations associated with fine-tuning the CI sound processor in a clinic. The aim of this study was to investigate to what extent CI recipients already accustomed to their clinically fitted program would adjust the settings in daily life if able to do so. Additionally, we studied the effects of these changes on auditory functioning in terms of speech intelligibility (in quiet and in noise), noise tolerance, and subjectively perceived speech perception and sound quality. Twenty-two experienced adult CI recipients (implant use >12 months) participated in this prospective clinical study, which used a within-subject repeated measures design. All participants had phoneme scores of ≥70% at 65 dB SPL in quiet conditions, and all used a Cochlear Nucleus CP810 sound processor. Auditory performance was tested by a speech-in-quiet test, a speech-in-noise test, an acceptable noise level test, and a questionnaire about perceived auditory functioning, that is, a speech and sound quality (SSQ-C) questionnaire. The first session consisted of a baseline test in which the participants used their own CI program and were instructed on how to use RAF. After the first session, participants used RAF for 3 weeks at home. After these 3 weeks, the participants returned to the clinic for auditory functioning tests with their self-adjusted programs and completed the SSQ-C. Fifteen participants (68%) adjusted their C-level frequency profile by more than 5 clinical levels for at least one electrode. Seven participants preferred a higher contribution of the high frequencies relative to the low frequencies, while five participants preferred more low-frequency stimulation. One-third of the participants adjusted the high and low frequencies equally, while some participants mainly used the overall volume to change their settings. Several parts of the SSQ-C questionnaire scores showed an improvement in perceived auditory functioning after the subjects used RAF. No significant change was found on the auditory functioning tests for speech-in-quiet, speech-in-noise, or acceptable noise level. In conclusion, the majority of experienced CI users made modest changes in the settings of their programs in various ways and were able to do so with the RAF. After altering the programs, the participants experienced an improvement in speech perception in quiet environments and improved perceived sound quality without compromising auditory performance. Therefore, it can be concluded that self-adjustment of CI settings is a useful and clinically applicable tool that may help CI recipients to improve perceived sound quality in their daily lives.