Tinnitus Phenotypes and Their Response to the Enriched Acoustic Environment (EAE) Treatment

Background/Objectives: The aim of this study was to apply data-driven clustering techniques for the subtyping of tinnitus severity to a retrospective cross-sectional cohort of 564 subjects. Additionally, the response of the resulting phenotypes to an enriched acoustic environment (EAE) treatment was investigated. Methods: A hierarchical decision cascade was applied to classify the measured audiograms of participants into six hearing loss (HL) patterns. K-clustering techniques were applied to demographic (gender), hearing (average audiometric threshold, HL pattern), tinnitus (tinnitus onset age, duration, severity, lateralisation, type of sound, aetiology) and emotional variables. Subjects received customised EAE stimulus to be listened to for one hour daily over four months. Results: Five phenotypes were found by applying K-clustering techniques to numerical and categorical variables. EAE provided an average tinnitus severity reduction of 24.3 points, which was clinically relevant and statistically significant, in 78% of subjects who completed the four-month treatment. Conclusions: Analysis of the performance of EAE treatment in the different phenotypes afforded clear differences in the composition of excluded, dropped out, and not improved subjects. Absolute mean improvement of both severity and emotional scores was larger in phenotypes PH3 and PH4, as they had higher tinnitus distress and emotional symptoms at baseline. Nevertheless, relative change of severity score was notably smaller in PH4.