Acoustics 1

[kammy]

When we take the following
1. sound transmission loss in dB ...does higher number mean higher loss
2. for loudness in sones GF when we measure value inside car does higher value of sones mean it is louder. also inside a vehicle we do we use sonesGF or sonesGD

 

[Hatch]

A higher transmission loss number means a higher loss. A higher sone level is also a higher sound level or louder sound.

Sones GF is the loudness index measured in a free field and sones GD is measured in a diffuse field.

I am not familiar with car measurements. I can only say that except for high frequency sound, the interior cannot be classified as free field or diffuse. High frequency sound has a very small wavelength which could approximate a point source and be considered in a free field. The same goes for a diffuse field. However the frequencies would have to be 1000 Hertz or higher. C. Hugh (

http://www.Hatch.ca)

 

[GregLocock]

The company I work for in Australia, use sonesGD for windnoise measurements in cars. There's about 1.5 sones difference between GF and GD.

There are a few point sources in windnoise eg the door mirrors and leaks, but once you have them sorted (which is a must) then you have line and area sources.

As to which you SHOULD use, well, ask your customer which he wants.

Cheers

Greg Locock