Bimodal success.

Rationale:

Since the 1990s, cochlear implantation (CI) has been the standard practice to restore hearing in severely hearing-impaired and deaf patients by providing multi-channel electrical stimulation to the auditory nerve. Current reimbursement regulations in the Netherlands only allow standard unilateral implantation. However, there is a growing interest in bilateral cochlear implantation and in the benefits of binaural hearing (hearing with two ears) in general. One way of providing binaural cues to unilateral CI recipients is to wear an acoustic hearing aid in the contralateral non-implanted ear, known as bimodal hearing.
The benefits of bimodal input (e. g. speech perception in noise, localisation, listening effort) can objectively be demonstrated in clinical research settings. However, in daily practice there are often patients who choose not to wear their hearing aid (anymore) after receiving a CI in the other ear. Why this is and how this can be improved is still an unanswered but very relevant question in fitting and advising these patients in clinical practice.



Objective:

This research project has 2 main goals and can therefore be divided into 2 parts:
The aim of part (A) is to qualitatively and quantitatively assess the daily-life experiences of CI-patients who do or do not wear a contralateral hearing aid. Assessing the subjective experiences of these patients is a research area that hasn’t been covered in literature yet.

The aim of part (B) is to identify the key contributors to successful bimodal fitting. There is still little known about the reasons why patients may or may not experience benefit from wearing a contralateral hearing aid.

After the assessment of these key contributors to bimodal success, a protocol will be developed that may result in a faster and better bimodal fitting. In future research these new insights may lead to clinical tools to create more successful bimodal users with improved hearing performance. Moreover, the results from this study will probably broaden the inclusion criteria for CI in combination with HA, making it available for a larger population of patients.



Study population:

This study focuses on severely hearing impaired adults who use a unilateral cochlear implant with or without a contralateral hearing aid (total n=70).



Study design:

In the first part of this study (A), unilateral CI-users will be asked to fill out a set of relevant daily-life questionnaires in the field of hearing experiences, sound quality and general quality of life. In this way their subjective experiences with wearing or not wearing a hearing aid in the contralateral ear will be reviewed.

In the second part of this study (B), the subset of bimodal users will be asked to partake in objective testing. The aim of this part is to investigate correlations between the benefit of their bimodal fitting (e.g. speech-in-noise and listening effort) and influencing factors (e.g. residual hearing, device fitting, spectral- and temporal resolution and overlap, loudness balance and cognitive skills).



Nature and extent of the burden and risks associated with participation, benefit and group relatedness:

Subjects participating in this study will be asked to fill out a set of questionnaires (A) and/or perform audiological-specific tests (B). Study associated risks are thought of as non-existent since this is an observational study with non-invasive or low impact tests and no direct interventions. Participation however takes time and effort from subjects.

The aim of the study is to identify key contributors to bimodal success. One may expect that based on these results the clinical practice of unilateral CI patients can be improved, both on an individual and on a group basis. The clinical goal is to enable patients to successfully use CI and HA together, receiving optimal benefit from their residual auditory abilities.

One way of providing binaural cues to unilateral CI recipients is to wear an acoustic hearing aid in the contralateral non-implanted ear, known as bimodal hearing.

The benefits of bimodal input (e. g. speech perception in noise, localisation, listening effort) can objectively be demonstrated in clinical research settings. However, in daily practice there are often patients who choose not to wear their hearing aid (anymore) after receiving a CI in the other ear. Why this is and how this can be improved is still an unanswered but very relevant question in fitting and advising these patients in clinical practice.

The hypothesis of this study is that more insight into the subjective experiences of these patients and the factors underlying bimodal benefit will help in developing bimodal fitting guidelines.

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