Are W/m^2 and dB both units of sound intensity? What is the difference between them?

Question

Are W/m^2 and dB both units of sound intensity? What is the difference between them?

1 Answer

Impact of this question

8460 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-03-21T16:31:00

See below.

Explanation:

Human perception of loudness (aka sound intensity) is observed to be proportional to log of the scientifically measured intensity.

So a scientific machine will measure sound intensity as it is defined - as sound power per unit area whose units are $\frac{W a t t s}{m^{2}}$ $(Wat\ts)/m^2$ .

But if the measurements are for human consumption, say the volume switch on a TV, it is better to use a log scale.

So, if we have measured $I_{o}$ $I_o$ as being the standard threshold of hearing intensity, ie what you can just about hear, in $\frac{W a t t s}{m^{2}}$ $(Wat\ts)/m^2$ , we get a more user-friendly metric $I_{d B}$ $I_(dB)$ if we say that:

$I_{d B} = 10 {log}_{10} (\frac{I}{I_{o}}) * d e c i b e l s *$ $I_(dB) = 10 log_(10) (I/(I_o)) **decibels**$

This means, for example, if $I = I_{o}$ $I = I_o$ then $I_{d B} = 0$ $I_(dB) = 0$ .

Science

Math

Humanities

... and beyond

Are W/m^2 and dB both units of sound intensity? What is the difference between them?

1 Answer

Explanation:

Related questions

Impact of this question