Cochlear Implants and Listening Effort: the Interaction of Cognitive and Sensory Constraints

Overview

This study examines how cochlear implant users understand and comprehend speech in realistic communication situations. Through six experiments measuring listening effort via pupillometry and discourse comprehension, we will investigate how linguistic context, cognitive demands, and processing time affect speech understanding in CI users, and in normal-hearing controls) to identify factors underlying communication resilience versus vulnerability and develop improved, ecologically valid assessment and rehabilitation strategies.

Detailed description

This research study examines how adults using cochlear implants (CIs) understand and comprehend speech in realistic communication situations. While current clinical tests focus on how well CI users can recognize single words and simple sentences, this study investigates whether success in recognizing speech sounds actually translates to understanding the meaning and content of longer conversations and discourse.

The study will include six interconnected experiments examining: (1) how CI users use linguistic context (both adaptively and maladaptively) to understand degraded speech; (2) how listening effort affects comprehension when faced with communicative challenges like remembering multiple sentences or narratives; (3) whether giving listeners control over the speed of speech presentation improves comprehension; and (4) a clinically-applicable version of these assessments.

Throughout the experiments, researchers will measure listening effort using pupillometry (tracking pupil dilation as an index of cognitive effort) combined with behavioral measures of speech recognition and comprehension. Comprehension will be assessed using a validated framework that distinguishes between understanding main ideas versus minor details in discourse passages.

The study will include cochlear implant users and normal-hearing adults listening to degraded speech simulations via vocoders. Participants will range in age from 18 to 80 years. A comprehensive baseline battery will assess perceptual abilities (speech recognition, spectral resolution, temporal processing) and cognitive abilities (working memory, processing speed, executive function).

OBJECTIVES:

Primary objectives are to identify mechanisms underlying successful speech comprehension in CI users and to determine factors associated with resilience versus vulnerability to communicative challenges. Secondary objectives include examining relationships between cognitive abilities, listening effort, and discourse comprehension outcomes.

OUTCOMES:

This research is expected to provide more ecologically valid assessment methods for CI users, identify which individuals may benefit from specific communication strategies (such as self-paced speech), and inform development of improved rehabilitation approaches that enhance real-world communication success rather than just word recognition ability.

Interventions

• Behavioral Experiment 1: Syntactic and Semantic Context
  * Recall of meaningful sentences, anomalous word strings, and unstructured word lists * Measurement of syntactic and semantic gain * Pupillometry during auditory and visual presentation
• Behavioral Experiment 2: False Hearing and Context Overuse
  * Two-choice word recognition task with semantic priming/luring in multi-talker babble * Three Signal-to-Noise Ratio (SNR) levels (heavy, medium, light noise) * Confidence ratings for responses * Pupillometry measurement
• Behavioral Experiment 3: Two-Sentence Problem
  * Speech recognition and recall of single sentences vs. paired sentences * Manipulation of inter-sentence semantic predictability (high vs. low) * Four test conditions: 1-sentence, 2-sentences, 2-sentences+pre-prompt, 2-sentences+post-prompt * Pupillometry during task
• Behavioral Experiment 4: Cascading Effects on Discourse Comprehension
  * Recall of 27 narrative passages (67-97 words each) * Propositional analysis scoring (main ideas, mid-level ideas, details) * Measurement of semantic hierarchy effect * Pupillometry during listening
• Behavioral Experiment 5: Self-Paced Discourse Comprehension
  * 24 discourse passages (150 words each): 12 narrative, 12 expository * Continuous presentation vs. self-paced presentation (stops at clause/sentence boundaries) * Measurement of pause times and comprehension recall * Pupillometry during task
• Behavioral Experiment 6: Clinical Application
  * Self-Paced Sentence Comprehension * Sentences with varying syntactic complexity (active-conjoined, subject-relative, object-relative) * Continuous vs. self-paced (with pause at major clause boundary) presentation * True/false comprehension verification statements * Pupillometry measurement

Primary outcome measures

• Percent correct Consonant-Nucleus-Consonant (CNC) words across experiments 1-3 [Time frame: End experiments 1-3 (up to 9 hours)]
• Percent correct AzBio sentences across experiments 1-3 [Time frame: End experiments 1-3 (up to 9 hours)]
• Error rates for word identification tasks across experiments 1-3 [Time frame: End experiments 1-3 (up to 9 hours)]
• Percentage of propositions recalled from narrative passages [Time frame: End of experiment 4 (up to 3 hours)]
• Ratio of main idea recall to detail recall [Time frame: End of experiment 4 (up to 3 hours)]
• Percentage of true/false statements identified [Time frame: End of experiment 6 (up to 3 hours)]
• Percent correct increase from unstructured word lists to anomalous sentences (syntactic gain) [Time frame: End of experiment 1 (up to 3 hours)]
• Percent correct increase from anomalous sentences to meaningful sentences (semantic gain). [Time frame: End of experiment 1 (up to 3 hours)]
• Number semantically-driven misrecognitions in lure conditions [Time frame: End of experiment 2 (up to 3 hours)]
• Frequency of semantically-driven misrecognitions in lure conditions [Time frame: End of experiment 2 (up to 3 hours)]

Eligibility criteria

Inclusion criteria

• Subjects will be otherwise healthy normal-hearing and cochlear implant (CI) adult listeners (between 18 and 80 years old).

Exclusion criteria

• Individuals below 18 years of age.
• Individuals with evidence of neurologic, vascular or psychiatric disease or dementia, and taking medications that might interfere with task performance.
• Individuals with a history of language disorders (besides those associated with hearing loss for the CI users). Individuals who are non-native speakers of American English.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: Yes

Study design

Allocation

Non-randomized

Model

Parallel assignment

Masking

Open label

Primary purpose

Other

Study locations

United States · 2 centers

• Brandeis University — Waltham
• NYU Langone Health — New York

Identifiers

NCT: NCT07279441 · 18-01806 · 2R01DC016834-06A1

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗