Acoustics type question on reflection....

[classicswiss]

Homework Statement

acoustics type question on reflection

Relevant Equations

see below

Hi, hopefully someone can help with showing me how I can work this one out as I am new to the topic area and a bit stumped.

A piece of machinery is emitting a sound power level of 100 dB at 40 kHz. Calculate the level of the return signal after reflection from a wall 5 m away using the following:

Reflection coefficient of the wall= 0.6
Air absorption=1.39 dB/m
Directivity angle of the sound emission from the machine= 48 degrees

any thoughts?

 

[berkeman]

Homework Statement:: acoustics type question on reflection
Homework Equations:: see below

Hi, hopefully someone can help with showing me how I can work this one out as I am new to the topic area and a bit stumped.

A piece of machinery is emitting a sound power level of 100 dB at 40 kHz. Calculate the level of the return signal after reflection from a wall 5 m away using the following:

Reflection coefficient of the wall= 0.6
Air absorption=1.39 dB/m
Directivity angle of the sound emission from the machine= 48 degrees

any thoughts?

Welcome to the PF.

We are not allowed to help you until you show your best efforts to work the problem. What are the Relevant Equations for 1) reflections and 2) attenuation of power during propagation?