Audio Engineering

Acoustic Environment 93

WhereS 1 is absorptive then the equation becomes:

Reflected signals relative level 

In the case of substantial transmission loss then

these losses can be added as required.

T.L. 20 log fw- 47 dB

*AssumingS 1 is nonabsorptive, nondiffuse,

and nonfocusing.

Ds Dm

2 DsDm

S 1 *

Image Loudspeaker

source

Microphone

Case No. 1

S 1 *

Dm Dms

Loudspeaker

Microphone

Case No. 2

Image

source

Influence of surface S 1 on measured signal at

microphone equals:

Reflected signals relative level  20 log[] 2 DsDm

Dm

Influence of surface S 1 on measured signal at

microphone equals:

Reflected signals relative level  20 log[]Dm 2 Dms

Dm

20 log[]Dm 2 Dms 10 log (1 α)

Dm

Figure 3.5 : Calculating relative levels of refl ections.