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 group with average 7.2 years of formal education) make significantly more BPO errors than the average adult population. It has been found that BPO errors (i.e. use of BPO pantomimes in place of the IO pantomimes dominant in typical adult individuals) are made by patients with schizophrenia. Given that BPO errors are associated with apraxia, and that past research has indicated that schizophrenic patients have apraxia-like symptoms, this is perhaps not a surprising finding. This BPO-schizophrenia association has not been extensively explored to date, and more research is required in order to better understand it. Body part as an object