In search of the best possible outcome for the severe hearing impaired who have regained the ability to hear by means of a cochlear implant (CI), electrical stimulation and the information it carries should match as closely as possible to what the human brain naturally has evolved to cope with and learned to process instead of relying on plasticity to adapt to an induced mismatch. At the moment, however, CI's are fitted with a 'one size fits all' principle. This is known to cause a mismatch between the frequencies presented by the CI electrode array and the frequencies represented at the corresponding natural acoustic location in an individual cochlea. In this study it is hypothesized that an individual imaged based fitting that pursues natural hearing alignment and is implemented from the start of the rehabilitation process, will improve the individual outcomes of electric hearing. The natural fitting strategy is thought to give rise to a steeper learning curve, result in a better performance in challenging listening situations, improve sound quality, complement better with residual acoustic hearing in the contralateral ear and win the preference of CI-recipients.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
30
Mapping of the electrical input of the cochlear implant will be based on an individualized natural frequency alignment as estimated with imaging methods.
MUMC
Maastricht, Limburg, Netherlands
RECRUITINGSpeech understanding in quiet with cochlear implant
Speech understanding with CI in quiet measured with the Dutch Consonant Nucleus Consonant (CNC) test.
Time frame: During the first 12 months of CI rehabilitation
Speech understanding in quiet with cochlear implant
Speech understanding with CI in quiet will be measured with the Dutch Matrix sentence test.
Time frame: During the first 12 months of CI rehabilitation
Speech understanding in noise with cochlear implant
Speech understanding with CI in noise will be measured with the Dutch Matrix sentence test.
Time frame: During the first 12 months of CI rehabilitation
Patient preference
At every fitting session, patients will be asked to rate their satisfaction with either the control or experimental program on a 10-point Visual Analog Sscale (1 dissatisfied - 10 very satisfied).
Time frame: During the first 12 months of CI rehabilitation
Speech understanding with hearing aid
Speech understanding with hearing aid will be measured with the Dutch Consonant Nucleus Consonant (CNC) test.
Time frame: During the first 12 months of CI rehabilitation
Speech understanding with hearing aid
Speech understanding with hearing aid will be measured with the Dutch Matrix sentence test.
Time frame: During the first 12 months of CI rehabilitation
Spatial masking
The Spatial Speech Perception In Noise (SSPIN) test will be used to determine the head shadow and squelch effect \[74\].
Time frame: During the first 12 months of CI rehabilitation
Listening effort
In a listening effort test subjects are asked to rate the effort it takes to listen to speech fragments in noise.The listening effort test is based on subjective ratings for the ease or difficulty involved in listening to speech in the presence of varying amounts of noise. Speech and noise are presented from the same loudspeaker in front of the subject. Three relevant signal-to noise ratios will be tested repeatedly (5 times) and the mean effort level will be calculated. Rating is performed using a vertical scale with 13 discrete points (seven named categories interspersed with an empty category) ranging from no effort (Score 0) to extreme effort (Score 12).
Time frame: During the first 12 months of CI rehabilitation
Spectral resolution (SMRT test)
The ability to spectrally resolve frequency information is known to be related to speech understanding performance (in noise). Frequency selectivity will be monitored to test the ability of the patient to filter out one stimulus from the others on the basis of frequency. This will be done with the Spectral-temporally Modulated Ripple Test (SMRT).
Time frame: During the first 12 months of CI rehabilitation
Loudness scaling (ACALOS test)
To estimate the course of loudness percept between minimal audible level and maximum comfortable level, a procedure is used that automatically adjusts the presentation levels to the subject's individual auditory dynamic range without employing any pre-measurement. The procedure uses repeated measurements and presents levels in randomized order. It has been named "ACALOS" (Adaptive Categorical LOudness Scaling). Results will provide information about the difference in loudness percept between CI and HA and will give input for optimizing the fitting of these hearing devices across the dynamic range.
Time frame: During the first 12 months of CI rehabilitation
Telemetric data
By measuring Evoked Compound Action Potential (ECAP), telemetric data on the function of the implant and the response of the auditory nerve will be collected.
Time frame: During the first 12 months of CI rehabilitation
Quality of life in relation to hearing ability.
Measured with the Speech-Spatial-Qualities (SSQ) questionnaire. A short form of the SSQ (SSQ-12) will be used. The SSQ is designed for use typically as a complement to behavioural or experimental measures of hearing ability and consists of questions on the following domains: speech hearing, spatial hearing, qualities of hearing, and listening effort. Participants will be asked to answer 12 questions on a 10-point Visual Analogue Scale with different units.
Time frame: During the first 12 months of CI rehabilitation
Overall wellbeing
Measured with the ICEpop CAPability measure for adults (ICECAP-A)
Time frame: During the first 12 months of CI rehabilitation
Overall Quality of life
Measured with the Health Utility Index Mark 3 (HUI-3)
Time frame: During the first 12 months of CI rehabilitation
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