Unable to ignore but this was in the link: Nixon (Nixon, 1973) used a piston-phone coupled to the subject’s ear via an earmuff to produce levels of 135dB at 18Hz. Six five minute exposures were used with one to two minute rest periods between. TTS was observed in one third of the subjects used, but this recovered after about half an hour. Later work (Burdick et al., 1978) indicated that there may be some permanent threshold shift (PTS) for long term high level exposure. In one experiment, chinchilla were exposed for three days to octave band noise at, 100dB, 110dB and 120dB centred on 63Hz. The highest level led to PTS of up to 40dB at 2kHz in the chinchilla. When human subjects were exposed to the same low frequency noise at 110dB and 120dB for four hours, a TTS of about 15dB resulted, extending from low frequencies up to 2kHz. The frequency used by Burdick et al is higher than in the other experiments and might be expected to have a greater effect. There is an indication that long-term exposure to very high levels may cause permanent hearing loss. My understanding of this is far from complete but the article tells me that the output of a decent sub is perfectly capable of damaging human hearing. ShadyJ's rep was all red until I fixed it not long ago IIRC. I'm going to put it back the way it was. It seems like argument is of higher priority than understanding for him and the row of reds served as warning of that.
