db(spl) and power - my brain won't work

That is of course assuming the distance remains constant eg 86db(spl) @

dB = 10*log10(P2/P1) ...Jim Thompson

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SPL = 20log(10)(pressure(measured)/pressure(ref)), where pressure(ref)= 20e-6Pa (power is pressure squared)

However, since you are already measuring two values of power, it's easier to look at this through the back door. You're putting in 10 times the power, so you should get out ten times the power, right? SPL2-SPL1 = 10*log10(Power(in2)/Power(in1))

"David Eather"

Pressure is analogous to voltage, an ideal speaker produces a pressure wave in air the same as the voltage wave being fed into it. So to double the pressure, one doubles the drive voltage level.

However, the relationship between dBs and power is always the same.

... Phil

That's for sound power level Lw, normalized at 0 dB = 1 picowatt, yes?

Sound pressure level Lp is dB = 20*log10(P2/P1), where 0 dB = 20 micro Pascals (The P1 figure)

That about right?

--Winston

dB's are always ratiometric. But I'm trying to remember SPL's... haven't designed a hearing aid for probably 30 years ;-) ...Jim Thompson

"Jim Thompson"

.... Phil

Thanks all!

its 96dB SPL

senior moment averted.