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[Phys-L] Acoustics: Does a speaker create a displacement antinode? (amplifier power)

Bernard,

I mean whatever comes out of he speaker that commonly gets measured in
terms of dB - say a mfr will claim that his speaker will "put out" 120 dB I
guess right at the front plane of the speaker enclosure.

So, I would need to know for this case what amplifier power would be
required to drive a speaker at 120 dB vs. at 110 or 100 dB.

Bottom line is that I am trying to add an environmentalism aspect to my
claim that extremely loud, outdoor, band music not only contributes to
sound pollution for a neighborhood, but it also wastes a lot more
electrical energy than one might expect.

Thanks, Bill



On Tue, Apr 8, 2014 at 4:46 PM, Bernard Cleyet <bernard@cleyet.org> wrote:


On 2014, Apr 08, , at 12:55, Bill Norwood <bnorwood111@gmail.com> wrote:

Hi Jeff,
Long shot here, but since you are looking a bit into audio:
If one increases by 10 dB the sound level out of a speaker at a specified
distance, by what factor has the amplifier power requirement increased?
Thanks, Bill Norwood, U of MD at College Park


You mean sound pressure level???? by sound level OR do you mean sound
intensity?

I measured in Watt/m^2
p " " Pa


I proportional ~ to p^2

http://en.wikipedia.org/wiki/Sound_intensity


Sound pressure level (SPL) or sound level is a logarithmic measure of the
effective sound pressure of a sound relative to a reference value. It is
measured in decibels (dB) above a standard reference level. The standard
reference sound pressure in air or other gases is 20 µPa, which is usually
considered the threshold of human hearing (at 1 kHz).

http://en.wikipedia.org/wiki/Sound_pressure


from these and knowing the log manipulation rules "you" can find "your"
answer.


bc lazy


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