Patrick Dixon;288599 Wrote: > Hmm, I think the onus is on you to prove that it's not.
That was done in 1927 and possibly earlier when the thresholds of human hearing were established. It's been studied many times since then as well (there's a reference from 2004 here): http://en.wikipedia.org/wiki/Hearing_threshold The results are that the minimum audible RMS pressure is about 2E-5 pascal (for this reason that level is usually taken to be 0dB when discussing SPL). That's for a listener in an absolutely silent environment listening to a tone. Of course what we're discussing here - a change in level of a pre-existing loud sound - is much, much harder to hear, and the thresholds are far higher. But I'll be extremely generous to your position and use this number. A sound 144dB above 2E-5 pascal is well above the limit of short-term hearing damage, and according to wiki is louder than a rifle being fired 1m from your ear: http://en.wikipedia.org/wiki/Sound_pressure_level#Examples_of_sound_pressure_and_sound_pressure_levels No home stereo I know of is capable of playing a sound that loud. Therefore signals at -144dB will never be audible from 1m away even at max volume, and I doubt they are audible even with your ear over the tweeter. Let's prove this a different way, using physics. The air pressure variation caused by the Brownian motion of air molecules are at around -23dB relative 2E-5 pascal (and it's a good thing we can't hear that well, or we'd be constantly hearing white noise). Now suppose we have an audio system adjusted so that full-scale music is at very high volume - say 100dB SPL. A signal at -144 dB is then -44dB below 2E-5 pascal. But Brownian motion effects are at about -25dB - so the effects on a speaker cone from a signal component at -144dB, even with volume cranked, are MUCH smaller than the random motions of the cone induced by collisions with individual air molecules. If you can hear that, you're magic. You should quite your job immediately and apply to James Randi for his $1,000,000 challenge. -- opaqueice ------------------------------------------------------------------------ opaqueice's Profile: http://forums.slimdevices.com/member.php?userid=4234 View this thread: http://forums.slimdevices.com/showthread.php?t=45736 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
