Worldwide experience with sequential phase-shift sound cancellation treatment of predominant tone tinnitus

OBJECTIVE: To report clinical data from six centres in the US, Western Europe and Asia which have used phase-shift sound wave cancellation for treatment of predominant tone tinnitus, from the first treatment in 2000 to 2009. METHOD: Clinical data were obtained from New York City, London, Erie (Pennsylvania, USA), Antwerp, Grottamare (Italy) and Kuala Lumpur, and summarised. RESULTS: A total of 493 patients were treated. A reduction in tinnitus volume (defined as > or =6 dB) was seen in 49-72 per cent of patients.