Acoustics type question on reflection....

In summary, the conversation discusses a question on acoustics and the need for help in solving it. The question involves calculating the level of the return signal after reflection from a wall, given the sound power level of a piece of machinery and other factors such as the reflection coefficient, air absorption, and directivity angle. The person asking the question is new to the topic and is seeking guidance.
  • #1
classicswiss
2
0
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?
 
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  • #2
classicswiss said:
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. :smile:

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?
 

1. What is reflection in acoustics?

In acoustics, reflection refers to the bouncing back of sound waves when they encounter a surface. This phenomenon occurs when the surface is hard and smooth, causing the sound waves to reflect off at an angle equal to the angle at which it hit the surface.

2. How does reflection affect sound waves?

Reflection can affect sound waves in several ways. It can either amplify or decrease the intensity of the sound, change its direction, or cause echoes. Reflection also plays a crucial role in how we perceive sound and can impact the overall quality of sound in a room or space.

3. What is the difference between specular and diffuse reflection?

Specular reflection refers to the reflection of sound waves off a smooth and hard surface, while diffuse reflection occurs when the surface is irregular and rough, causing the sound waves to scatter in different directions. Specular reflection produces clear echoes, while diffuse reflection creates a more dispersed sound.

4. How does the angle of incidence affect reflection in acoustics?

The angle of incidence refers to the angle at which the sound wave hits the surface. In acoustics, the angle of incidence is essential because it determines the angle at which the sound wave will reflect off the surface. The angle of reflection is equal to the angle of incidence, following the law of reflection.

5. How can reflection be controlled in acoustics?

Reflection can be controlled in acoustics through the use of sound-absorbing materials, such as acoustic panels, diffusers, and bass traps. These materials can reduce the amount of sound that reflects off surfaces, improving the overall acoustic quality of a room or space. Proper placement of these materials is crucial in controlling reflection effectively.

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