SOUND Trial

Both the intervention and control arms receive bilateral hearing aid fitting, allowing the trial to isolate the net effect of the behavioural adherence component. The trial targets 150 participants aged 60–85 years with concurrent hearing loss and MCI, with a sample size inflated from 64 per arm to 75 per arm to accommodate a 15% dropout rate. The SOUND trial is a two-arm, single-blinded, parallel-group RCT conducted at Peking University First Hospital in Beijing, China. SOUND is described as the first RCT worldwide to examine the effect of a family-supported, theory-driven HAU behaviour intervention on cognitive outcomes in older adults with concurrent hearing loss and high dementia risk. The primary analysis follows the intent-to-treat principle using last observation carried forward for missing data, with a difference-in-difference approach for comparing cognitive function change. Participant blinding is not feasible given the nature of the control condition, introducing potential performance bias. The 4-month follow-up may be insufficient to detect cognitive change, as some evidence suggests longer periods are needed.