2. misc-audio
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Perception and Watts: Doubling of power

There's a curious rule of thumb, which to my ears seems mostly true:

  • To double the perceived volume, you must output 10x more power.

10x power = 10 dB by the way.  We've read this as we were buying amps and trying to decide between 100w/channel and 150w/channel.  We are told, repeatedly that 50 W difference isn't really that much.

On more than one occasion I've tested this and found it's pretty much spot on.  Here's my question:

How can any of us really tell what half as loud, or twice as loud is?

I mean, think about this for a bit.  I cannot tell half as bright, or twice as bright, but it seems I actually CAN tell what half as loud is.  How does this even begin to work in the ear/brain mechanism?? 😁

erik_squires

Showing 1 response by gregm

gregm
3,396 posts
 

I really did just want to ask, how can we tell what twice as loud is? I mean, I think I can, and it happens to match 10 dB.

Hi Erik, twice the volume, i.e. twice as much sound pressure level, is 6dB(spl). And this requires 4x the power in watts.

It seems that 10dB is what most of us perceive as double sound intensity, i.e. from a psychoacoustic point of view.

And even then, our perception is affected by the frequency. The lower the frequency, the lower our sensitivity, so +10dB may not be enough in the bass, for example... Interesting stuff!

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