Listening effort among adult cochlear implant users: a protocol for a systematic review and measure-specific meta-analysis

Background Cochlear implants (CIs) are the standard of care for profound deafness, yet clinical success is often measured solely by speech recognition scores. These metrics provide an incomplete picture; they indicate what a patient hears but fail to account for the mental workload required to achieve that performance. Objective The primary goal of this meta-analysis is to quantitatively compare the magnitude of listening effort in post-lingually deafened adults using cochlear implants (CIs) versus normal-hearing controls. Secondary goals are to: (1) evaluate within-group CI contrasts under varying task demands and signal-to-noise ratios; (2) compare the sensitivity and effect sizes of listening effort across subjective, behavioural and physiological measurement domains and (3) conduct planned subgroup analyses to assess the impact of clinical characteristics on listening effort. Methods and analysis This protocol adheres to Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Protocols (PRISMA-P) guidelines. A comprehensive systematic search will be conducted from inception to the present across MEDLINE, Embase, Scopus, CINAHL, PsycInfo and Cochrane Central. The review focuses on post-lingually deafened adults (≥ 12 months device experience and ≥18 years of age). We will employ a measure-specific meta-analytical approach, synthesising data separately across three domains: subjective (eg, self-reported scales), behavioural (eg, dual-task paradigms), and physiological (eg, pupillometry). Pooled effect sizes ( Hedges’ g ) will be calculated using a random-effects model. Statistical heterogeneity will be assessed via I 2 and Χ² statistics, while the certainty of evidence will be evaluated using the GRADE approach. By quantifying the disparity between speech accuracy and mental workload, this review provides an evidence-based framework for clinicians to identify patients at risk of chronic communicative fatigue, regardless of speech perception scores. Furthermore, this synthesis will guide future research by identifying which measurement modalities are most sensitive for monitoring the neurocognitive demands unique to auditory rehabilitation via CIs. Ethics and dissemination As this study involves the secondary analysis of publicly available data, external ethical approval is not required. The findings will be disseminated through a peer-reviewed publication. PROSPERO registration number CRD420261278088