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

Sorry all,

The brain is a bit stuck this morning. I want to be able to answer this question:

If an electromechanical speaker outputs sound at 86db(spl) @ 1 watt then it outputs 96db(spl) @ 10 watts (or is it 106db(spl)??)

I'm just stuck in a senior moment that caffeine hasn't been able to fix.

TIA

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

1 watt @ 1 metre etc
Reply to
David Eather

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

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| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

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))

Reply to
krw

"David Eather"

** The term is: "dB SPL ".

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.

+10dB = ten times power.

... Phil

Reply to
Phil Allison

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

Reply to
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

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

"Jim Thompson"

** Wrong.

.... Phil

Reply to
Phil Allison

Thanks all!

its 96dB SPL

senior moment averted.

Reply to
David Eather

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