The honest answer is: sometimes — and the outcome depends heavily on what "work" means to you, how consistently you use the app, and whether your expectations match what the research actually measures. Apps do not cure tinnitus. But the evidence suggests they may meaningfully reduce distress for a proportion of users — if used consistently.
Medical disclaimer: This is general information, not medical advice. If you have new, sudden, one-sided, or worsening tinnitus, consult a qualified healthcare professional.
