[linux-audio-dev] scaling jackinput to dbSPL

[Lee Revell]

On Tue, 2006-08-15 at 16:51 +0100, Dan Mills wrote:
> This is dependent on the microphone, preamp and sound
> card in use, or for the output case, the soundcard,
> power amp gain and speaker sensitivity (plus room
> effects). 
> 
> You need to ensure that 120dbSPL at the transducer
> does not clip either hhe mic, preamp or soundcard and
> then find out what sample value this gives with your
> hardware. Calibrate that point as 120dbSPL, then as
> long as all your hardware is linear the rest of the
> thing will just work.  

FWIW, there is some work going on in ALSA to make the drivers use dB
units for the mixer, rather than arbitrary scales.  But of course this
will only work for devices for which the developers have the full
hardware specs.

Lee