Listening Effort in Cochlear Implant Users

Inclusion Criteria: To be eligible for this study, a participant must: * Be an adult between the age of 18 to 75 years * Have had normal hearing and speech/language development as a young child * For younger NH listeners: have normal audiometric thresholds below 25 dB HL at frequencies between 250 and 8000 Hz * for cochlear implant listeners: at least 6 months experience with a cochlear implant * For older (55+ years) age-matched listeners with no cochlear implant: normal audiometric thresholds below 25 dB HL at frequencies between 250 and 2000 Hz and thresholds below 35 dB HL (hearing level) between 4000 and 8000 Hz * For cochlear implant listeners: be able to recognize spoken words in English at a rate of at least 50% * Be a competent speaker of north American English * Lack language-learning or other cognitive disabilities * Lack of auditory neuropathy spectrum disorder Exclusion Criteria: * unable to fix gaze position * eye disease preventing typical changes in pupil dilation * lack of perceptual and productive fluency in English