Re: Theoretical limit for loud music??

From: Guy Macon (http://www.guymacon.com)
Date: 09/04/04 

Date: Sat, 04 Sep 2004 04:10:14 -0700

Kevin Aylward <salesEXTRACT@anasoft.co.uk> says...
>
>Guy Macon wrote:

>>SPL is a function of the
>> velocity and the mass of the medium.
>
>Yes, but technically its the momentum. Light has pressure, but no "rest
>mass".

I thought we were talking about air approaching lightspeed.

>> Unlike the negative limit
>> which is hard clipping at zero pressure (vacuum), approaching
>> the positive limit is a matter of pouring more and more energy
>> into attempting to accelerate the medium, only to have that
>> energy turn into mass rather than velocity at the E=MC2 rate.
>> This additional mass allows higher pressures, and can approach
>> infinity if you pump enough energy in.
>
>That's not quite how it works though. This "mass increase" bit is a bit
>of a misnomer. Mass itself, doesn't actually increase. No professional
>physicist uses the concept at all, well, accept when writing popular
>paperbacks.

News to me - but then again, I am an eclectronicsite, not a Physicsoid...

http://www.google.com/search?q=physics++%22mass+increases%22

>***, now I have to go and think about when what gets applied to what,
>certainly this pops up (quick search) as an example:
>
>http://www.as.utexas.edu/astronomy/education/spring01/lambert/classnotes16.html
>"The Heisenberg Uncertainty Principle also contains the seeds to setting
>a limit on how massive a white dwarf can be. Remember, nothing goes
>faster than light, so the maximum momentum of an electron is set by the
>speed of light and so there is a maximum pressure provided by degenerate
>electrons. This maximum sets the maximum mass that a white dwarf may
>have"
>
>This is one of those things that cropped up in class, now with the
>qualifiers forgotten. I'll have to do some more investigations as to
>when the limit applies...
>
>Kevin Aylward
>salesEXTRACT@anasoft.co.uk
>http://www.anasoft.co.uk
>SuperSpice, a very affordable Mixed-Mode
>Windows Simulator with Schematic Capture,
>Waveform Display, FFT's and Filter Design.
>
>