Arnold Krille wrote:
Hi Paul and all (that rhymes :-),
2007/2/27, Paul Winkler <pw_lists@xxxxxxxxxx>:
On Tue, Feb 27, 2007 at 10:40:46PM +0100, Arnold Krille wrote:
> 120dB is the difference between just loud enough to be heard by your
> ear (1dB) and the loudness when the bones in your ear bow to protect
> it. At higher levels (>120dB) your ear aches but it will recover if
> the noise isn't permanent. At least thats the definition I learned...
I got my numbers from http://en.wikipedia.org/wiki/Decibel#Safety but
obviously their numbers represent some sort of typical examples; I
been in a number of discotheques (here in the US we can't pronounce
that so we just say "clubs") that had sound levels far above 100 dB.
The amount of time the ear can be exposed to a given sound pressure
level before sustaining permanent damange clearly varies a lot from
person to person. But government standards are probably a good
guideline to start with, eg. OSHA table G-16:
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=9735
I stand corrected, my numbers where from my physics-book which states
that 120dB is the "Schmerzgrenze" and 0dB is the slightest whisper
human ear can hear. Problem is that these values vary on the frequency
so there is a correction curve standardised(?)
Fletcher-Munson did the first (I believe) curves:
(http://en.wikipedia.org/wiki/Fletcher-Munson_curve
Others have refined.
see more: http://en.wikipedia.org/wiki/Equal-loudness_contours
in some A-something
paper so these corrected values for the human ear are called db(A)...
Yeah... dB doesn't mean a whole lot unless there is a reference.
see also: http://en.wikipedia.org/wiki/A-weighting
The OSHA standards _are_ important, so it's good that you listed them.
--
brad fuller
http://www.Sonaural.com/
+1 (408) 799-6124
