Effects of Listening Effort on Sentence Processing and Memory (Study 1)
Condition: Sentence Stimulus; Auditory Noise
Study type: Interventional

Summary: 
      Sensorineural hearing loss (SNHL) is among the most prevalent chronic conditions in aging and
      has a profoundly negative effect on speech comprehension, leading to increased social
      isolation, reduced quality of life, and increased risk for the development of dementia in
      older adulthood. Typical audiological tests and interventions, which focus on measuring and
      restoring audibility, do not explain the full range of cognitive difficulties that adults
      with hearing loss experience in speech comprehension. For example, adults with SNHL have to
      work disproportionally harder to decode acoustically degraded speech. That additional effort
      is thought to diminish shared executive and attentional resources for higher-level language
      processes, impacting subsequent comprehension and memory, even when speech is completely
      intelligible. This phenomenon has been referred to as listening effort (LE). There is a
      growing understanding that these cognitive factors are a critical and often "hidden effect"
      of hearing loss. At the same time, the effects of LE on the neural mechanisms of language
      processing and memory in SNHL are currently not well understood. In order to develop
      evidence-based assessments and interventions to improve comprehension and memory in SNHL, it
      is critical that we elucidate the cognitive and neural mechanisms of LE and its consequences
      for speech comprehension. In this project, we adopt a multi-method approach, combining
      methods from clinical audiology, psycholinguistics, and cognitive neuroscience to address
      this gap of knowledge. Specifically, we adopt a novel and innovative method of co-registering
      pupillometry (a reliable physiological measure of LE) and language-related event-related
      brain potential (ERP) measures during real-time speech processing to characterize the effects
      of acoustic challenge and LE on high-level language processes (e.g., semantic retrieval,
      syntactic integration) and subsequent speech memory in older adults with SNHL. This
      innovative work addresses a time-sensitive gap in the literature regarding the identification
      of objective and reliable markers of specific neurocognitive processes impacted by acoustic
      challenge and LE in age-related SNHL.
    

Detailed description: 
      This experiment is a BESH (Basic Experimental Study with Humans) Trial. All participants are
      exposed to all experimental conditions (i.e., "interventions") in a complete factorial 2 x 3
      within-subjects experimental design. Participants will consist of 80 older adults between the
      ages of 60 - 90 who will be recruited from the Salt Lake metro community. Participants will
      be recruited through the Utah Senior Ears database, the Utah Center on Aging, through flyers
      placed throughout the community (e.g., bulletin boards, waiting area in the ENT clinic at the
      University of Utah), through on-line advertisements (e.g., Facebook) and via word-of-mouth.
      Participants will be compensated with financial incentives. The investigators will recruit
      for an approximately equal number of participants into two hearing groups based on their
      pure-tone average (PTA) thresholds: normal hearing (PTA of < 25 dBHL, 1-4kHz) and
      clinically-relevant hearing loss (PTA of > 25 dBHL 1-4kHz). While the investigators adopt
      this dichotomous grouping for recruitment, hearing level will be treated as as continuous to
      increase statistical power.

      The investigators will follow all APA guidelines with respect to the treatment of human
      subjects. All participants will provide informed consent after study procedures are explained
      to them and the voluntary nature of participation will be emphasized. No identifying
      information (e.g., names) will be obtained from participants and the only information
      connected to their data files will be a unique, arbitrary code.

      Study procedures will be conducted within a single session, lasting between 3-4 hours.
      Following informed consent, participants will complete a standardized hearing assessment,
      neuropsychological assessment, audibility control assessment, and then participant in the
      EEG/pupillometry experiment, each of which is described below. All data will be stored on
      password-protected computers in the PI's laboratory. All material from participants will be
      collected specifically for research purposes. The only identifying information that is
      collected about subjects is their names, which will be used to recruit and compensate
      participants, but will not be linked to their data in any way. The materials presented in
      these studies have no known potential to stress, embarrass, stigmatize, or incriminate
      experimental participants.

      Prior to the beginning of the experiment, two audiometric tests will be conducted via an
      MA-41 audiometer via RadioEar IP-30 insert air-conduction earphones. First, pure-tone
      thresholds will be measured using the modified Hughson- Westlake at octave frequencies from
      250 to 8000 Hz for each ear. Second, speech recognition thresholds (SRTs) will be measured
      using a recorded Central Institute for the Deaf (CID) W-1 spondee word list Near visual
      acuity was also tested for both the right and left eye using the Rosenbaum visual acuity
      test.

      Participants will then complete a brief battery of cognitive assessments. (a) the Montreal
      Cognitive Assessment (MoCA). Although the appropriate cut-off score for cognitive impairment
      in the MoCA is variable across samples, individuals scoring below 20 are generally considered
      to be at increased risk for MCI. Participants will also complete the F-A-S phonemic fluency
      task as a measure of verbal fluency, via the short- form computerized version of the reading
      span task as a measure of verbal working memory, and the extended range vocabulary tests from
      the ETS Kit of Factor Referenced Cognitive Tests, as a measure of verbal ability.
      Participants will then complete an audibility control task. For this task, the same native
      speaker of American English will be used to record the stimuli at the same +3dB. Participants
      will hear nine different test sentences (e.g., "Don't touch the wet paint) and will be tasked
      with "shadowing" each sentence by repeating out loud each word as it was heard. The immediate
      repetition is done to reduce the contribution of any memory components to task performance.

      Following the audiological and neuropsychological testing, the primary experiment will begin.
      Electrophysiological data (EEG), pupil dilation measurements (pupillometry), and behavioral
      recordings will be made from participants. EEG will be recorded from 64 silver-silver
      chloride electrodes embedded in an EasyCap (Electro-Cap, Inc), following a 10-20 montage. In
      addition, an electrode will placed on the left infraorbital ridge to monitor for vertical eye
      movements and blinks, and a virtual bipolar horizontal electrooculogram channel will be
      created offline for monitoring horizontal eye movements by calculating a difference between
      two fronto-temporal electrodes FT10-FT9 that sit posterior to the outer canthus of each eye.
      The continuous EEG will be amplified with a BrainAmp DC amplifier (Brain-Vision, LLC,
      Morrisville, NC) (bandwidth filtered: 0.02-250 Hz) and recorded to hard disk at a sampling
      rate of 1000 Hz. Electrode impedances will be kept below 5 kOhms. During the listening task,
      pupil size measurements will be continuously recorded from the right eye using an Eyelink
      1000 Plus desktop mounted infrared eye tracker camera distributed by SR Research (SR Research
      Ltd., Ottawa, ON, Canada).

      Participants will be tested in a quiet sound-attenuated testing room. Participants will be
      seated 85 cm from a 24-in high- performance LCD monitor that will be used to present
      instructions and cues to the participant (e.g., when to take a break). Speech stimuli will be
      presented through the sound card of the stimulus presentation computer and routed to a MAICO
      MA-41 audiometer via the auxiliary channel, allowing for direct control of stimulus
      intensity. The audiometer will route the speech to the participant via RadioEar IP-30 insert
      air-conduction earphones. Stimuli will be presented presented at 65 dB HL for all
      participants to their better hearing ear (based on PTA thresholds between 1-4 kHz). All
      hardware is calibrated to standard in our testing room by a NASED certified technician.

      There will be 360 trials. On each trial, participants will listen to a sentence that contains
      a single target word that will either be a normal plausible continuation, a semantic
      violation, or a syntactic violation (see Table 1 in Research Plan). In addition, sentences
      will be presented either in +3dB SNR stationary speech-shaped background noise or will be
      presented in quiet (no background noise), in a 2 x 3 within-subjects factorial design.

      After the end of the 360 sentences, a delayed recognition memory task will be administered.
      Participants will be visually presented with 360 test sentence frames on a tablet computer,
      each with the target word missing. They will be instructed to mark whether or not they
      recognized each sentence as one that they had heard during the experimental task. For the
      sentences they reported as having heard previously, they will be asked to recall the target
      word to the best of their ability by typing their response. There will be no time limit on
      the memory test. 180 of the sentences will be old items that they had heard during the task
      and the other 180 will be semantic foils. This approach has been validated in past studies on
      listening effort and recognition memory.

      Upon completion of the memory assessment, the study procedures will be complete. Participants
      will be debriefed, receive compensation, and will have the opportunity to ask any questions
      of the study team.
    

Intervention name(s): Sentence Stimulus; Auditory Noise
Intervention type(s): Other; Other
Intervention description(s): The sentences are designed such that a specific target word is either (a) Plausible (normal), (b) a semantic pragmatic violation, or (c) a morpho-syntactic violation. Example: e.g., "Every morning at breakfast, the boys would (A: EAT)/ (B.PLANT )/ (C. EATS ) eggs..."; The sentences will be presented either A) in quiet, or B) with speech- shaped stationary background noise presented 3dB below the speech.
Intervention model: Single Group Assignment
Intervention model description: This basic science experiment meets the NIH criteria of a BESH (Basic Experimental Study with Humans) Trial. All participants are exposed to all experimental conditions (i.e., "interventions") in a complete factorial 2 x 3 within-subjects experimental design. "Interventions" involve presenting various speech stimuli to participants.
Masking: None (Open Label)
Primary purpose: Basic Science