Impact of tinnitus, noise and noise reduction on processing effort: a pupillometry study

Hearing loss affects processing effort, potentially making speech perception in noi-se exhausting. To achieve successful speech understanding, people with hearing impairment need to increase their effort, particularly in listening conditions with low signal-to-noise ratios (SNRs). Research with pupillometry indicated a benefit of noise reduction algorithms for people with hearing-impairment, where a decreased peak pupil dilation (PPD) reflected a reduced effort. Tinnitus may increase the pro-cessing effort further due to the perception of an extra sound stimulus and a general effect of the tinnitus on quality of life. The present study aims to investigate the effect of tinnitus on processing effort while performing a speech recognition task as indicated by the PPD response. Another objective is to examine the benefit of a noise reduction (NR) scheme on effort. For a group of hearing-impaired listeners with tinnitus and a control group of hearing-impaired participants without tinnitus, the PPD response was recorded during sentence recognition, in a design with 2 SNRs (corresponding to the individual 50% and the individual 95% intelligibility level) x 2 algorithm modes (NR active vs. inactive). Furthermore, questionnaires are applied to evaluate perceived fatigue and tinnitus. It is expected that hearing-impaired participants with tinnitus will have an increased PPD compared to control participants. Since tinnitus has been found to have a larger impact in quiet surroundings, it is hypothesized that the tinnitus participants will have less benefit of the NR scheme in the condition corresponding to the individual 95% speech intelligibility level. Ultimately, it is also hypothesized that more severe subjective ratings of tinnitus and fatigue will correlate with increased processing effort in the speech recognition task. The results of the study will be presented and discussed.