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.
Body part as an object aphasics have been put forward since then, including intellectual degradation, and the inability to carry out pretended actions. Denny-Brown takes a more holistic approach and suggested ideational apraxia results from diffuse brain damage. Body part as object is a relatively new concept in scientific literature. Past studies have suggested that BPO pantomimes may allow aphasics to avoid an impaired cognitive function. By not having to reproduce a movement outside of the usual context, they can have a more vivid experience of acting on an object. What is known as BPO pantomiming in children was first discussed in Goodglass and Kaplan’s