Effect of a sound processor on listening effort in Cochlear Implantees

Design Overview Cochlear implant recipients aged greater than 18 years will be asked to participate. A single-subject research design (in which each subject serves as his or her own control) is appropriate since it accommodates the heterogeneity that characterizes hearing-impaired populations. The study will use a prospective, sequential enrolment, within-subject design where each subject is his/her own control (repeated-measures). The noise reduction algorithm will be randomly programmed to the sound processor CP1000 in Program 1 or Program 2 by the cochlear implant audiologist. The participant and the investigator conducting the assessment will be blinded to the program allocation Visit One: will take place at participant’s primary programming centre, the University of Auckland Clinics. During this visit the participant will sign the consent form. The participant’s audiologist will provide the Cochlear N7 device (which will be used continuously throughout the 8 weeks of the study) and convert the participant’s CP900 to the CP1000 sound processor programs with the recipient and will randomize the noise reduction algorithm into Program 1 or Program 2 (noise reduction system is designed to attenuate background noise levels in each channel while retaining speech information). Both programs are activated throughout the 8 weeks of the study and the participants are encouraged to select both programs for listening in everyday life using their remote control so that the participant gains listening experience with both programs before being tested. During testing sessions the researcher will select the program to be evaluated one at a time. Participants will be instructed to use both programs (Cochlear N7 device) during the acclimatization period (period of time where there is an improvement of speech perception due to auditory processing changes) but they will not be told which program has the noise reduction, If any problems arise with the device they will still have their own usual device. Visit 2 will be scheduled 2 weeks after Visit 1 at a time convenient for the participant. Visit two: Participants will complete different assessments as described below using the Cochlear N7 device. Cognition is tested at the beginning in visit two only, with the participant wearing their hearing devices set to their preferred settings. After the cognition test the single and dual tasks will be completed with each program activated in turn, in counterbalanced order. During this visit participants will complete a hearing quality questionnaire (SSQ-C) regarding their self-perception of difficulty in various everyday situations. Participants will be scheduled for the third and last session in 2 weeks’ time. Visit three (two weeks after visit 2): During this session participants will be asked to repeat the same assessments and questionnaires as visit 2 (for both programmes). They will also be interviewed briefly to find out how they found the trial and the assessments. After the assessment, the primary audiologist will return to the primary programming using the participant’s current device. Participants will return the Cochlear N7 device and all the parts provided. CI programming and testing will conducted by a senior CI Implant rehabilitationist and audiologist respectively. Each session will have a duration of 2 hrs approximately. Adherence to the use of the device will be measured by checking on the datalog (software function) for example how many hours per day they are wearing the processor and which sound environments they have been in. This information will be obtained by the CI implant rehabilitationist. Evaluation Materials and Test Conditions Cognition assessment WAIS-IV Digit Span: The Digit Span test includes three different digit span tasks (Forward, Backward, and Sequencing). Forward digit span requires the participant to recall number sequences in the same order as they are presented. Backward digit span requires the participant to repeat the number sequences in reverse order. For the sequencing task, participants are instructed to order the presented number sequence from highest to lowest number. Reading Span test: Reading span is a Working Memory test designed to tax memory storage and processing simultaneously. The original reading span test was introduced by Daneman and Carpenter (1980). The participant’s task is to comprehend sentences and to recall either the first or the final words of a presented sequence of sentences. The percentage score of correctly recalled words out of the total number of presented words determines the performance measure. Duration: 15 minutes approximately Prior to data collection during visits two and three, practice will be provided for each task described below until the participant is familiar with the task and has understood the instructions clearly (this will take about 30 minutes in total). Single Task paradigm Speech recognition in noise (Primary task) The primary task will be a sentence-in-noise task presented at a fixed overall speech performance level of 50% correct performance (50% SRT) using the adaptive Australian Sentence Test in Noise (AuSTIN) sentences (Dawson, Hersbach, & Swanson, 2013). Participants are instructed to repeat back the sentences presented from a loudspeaker (single spatial configuration with the signal and noise at 0°; front). Thirty sentences will be used to obtain the 50% speech recognition threshold (SRT) scores. The verbal response times to auditory stimuli (VRT) will be obtained, which is calculated from the offset of the stimulus, as logged by the experimental program, to the onset of the verbal response (Pals, Sarampalis, van Rijn, & Baskent, 2015). Two measures will be obtained using both CI programs Duration: 10 minutes in total approximately (using both programs) Visual reaction time (Secondary task) The visual task was developed based on Sternberg’s (1966) short-term-memory-scanning paradigm. Stimulus presentation and response recording is run on a 17 inch laptop using Inquisit 4 software. Participants are presented with a series of digits (one to six digits long) in white on a black background. Following this the participants are prompted with a target digit (yellow on a black background) and are required to indicate if it was either part of the series or not, using one of two keys on the keyboard. The software calculates reaction time (RT) and accuracy for each response. Each block consisted of 18 trials. paradigm. RTs are displayed on the computer monitor after each trial. Two baseline measures will be obtained, using both CI programs. Duration: 10 minutes in total approximately (using both programs) Dual Task-paradigm After primary- and secondary- single task measures are obtained, the dual-task paradigm will be administered to participants. In the dual task, participants are told that their main task is to repeat the sentences, but they should do the visual task as best they can at the same time. Measures are obtained using both programs. After each dual-task assessment participants complete questionnaires examining listening effort Participants repeat the Secondary visual task at the end of the dual task paradigm test-session to verify that performance is not affected by learning or fatigue. Duration: 10 minutes in total approximately (using both programs) General comments The total duration of the study for the participant will be no more than 8 weeks. The participants will be required to visit their cochlear implant clinic at the University of Auckland three times as part of the study. Recruitment will be through advertisements at The University of Auckland Hearing Clinic. At Visit 1 the participant will be screened and consented and thus enrolled into the study. At this time the participants will be given 2 programmes in the investigation Cochlear N7 device. The participants will be asked to keep diary notes of anything they notice about program 1 and program 2 during the 2-week period between visit 1 and visit 2 Visit 2 will occur approximately 2 weeks after visit 1. At Visit 2 the participant will complete the study assessments: subjective questionnaires, speech testing (primary task), visual reaction test (secondary task) and dual-task paradigm. Visit 3 will occur approximately 2 weeks after visit 2. The same tests will be administered as visit 2.