Tinnitus masker issues associated with use of tinnitus maskers: the "safe" level of continuous sound depends on the duration of the sound. For maskers worn continuously, or most of the day, a safe level is no more than 70db, in accordance with EPA maximum safe exposure level for 24-hour environmental sound. Maskers louder than 45db or so (the ambient background level of an average home living area) may start to interfere with understanding conversation (about 60db). Masking of high frequency tinnitus (>6,000hz) is difficult because of the resonance characteristics of the human ear as well as high frequency limitations of in-ear devices.
Tinnitus masker for hearing loss. Sound generators (masking devices) have received Class II approval from the FDA. However, they are considered to be “experimental, investigational, or unproven” therapies. There is one report of a bone conduction vibration masker that transmits a 60 Hz fundamental with adjustable harmonics up to 1000 Hz. A commercial device based on the phenomenon (Aurex3) was approved by the FDA. A new development in tinnitus management is the use of high audio (10 kHz-20 kHz) or ultrasonic (20-100 kHz) via bone conduction. A 2012 Cochrane Review stated the available studies do not show strong evidence of the efficacy