# Loudspeaker question



## derekleffew (Oct 27, 2008)

From avare:

> A speaker that is 100% efficient is hung in the air so that all sound from the speaker radiates equally in all directions. What would be the SPL at 1 meter from the speaker with a 1 watt input?


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## avkid (Oct 27, 2008)

At what frequency are we measuring?


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## avare (Oct 27, 2008)

My apologies. I suggested the question and forgot a key point with regards to frequency. The speaker is much smaller than the wavelength of the frequency being produced, so it is acting as a point source.

Andre


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## derekleffew (Oct 27, 2008)

Is it even possible for "all sound from a speaker to radiate equally in all directions"? Would this be akin to measuring the output bare light bulb without a reflector where the spherical surface area, 4∏r^2, comes into play?


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## avare (Oct 27, 2008)

derekleffew said:


> Is it even possible for "all sound from a speaker to radiate equally in all directions"? Would this be akin to measuring the output bare light bulb without a reflector where the spherical surface area, 4∏r^2, comes into play?



When the size of the speaker is small (less than 1/4 of the wavelength is one standard used in physics texts) then yes, all sound will radiate equally in all directions. The intent of the question is that the speaker is a point source, so the speaker surface area does not come into play.

That gives an idea for another question in the future. Thanks!

Andre


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