Reflection of sound. Changes to its properties.

In summary, the conversation discusses the potential changes in frequency, intensity, wavelength, and velocity of a pure tone when it is reflected off a flat wall. It is mentioned that if the wall is moving, the Doppler effect may be observed. However, if the wall is stationary, the only change that may occur is a decrease in intensity, unless the sound is measured very close to the wall where it may be enhanced. This phenomenon is used in pressure zone microphones to increase sensitivity.
  • #1
buggsndirk
2
0
Hi guys and girls,

Just had a question I have been thinking about for a while.

Suppose you have a sound maker than makes a pure tone at a particular frequency. You play this tone for an instant directed directly at a flat wall (not absorbent at all). If you could measure the reflected tone would there be any change in frequency, intensity, wavelength or velocity?

My gut feeling is that the intensity will lower somewhat, but nothing else will change, but I have a feeling I'm missing something super obvious like a doppler effect or something.

Any and all thoughts are appreciated.

Thanks
 
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  • #2
Is this wall moving?
If it is moving away, then each wavelength will be reflected a little bit later, which is the Doppler effect (called red shift).
If it is moving toward you, the each wavelength will be reflected a little bit earlier, also the Doppler effect (blue shift).
 
  • #3
Everything is stationary.

so nothing will change?
 
  • #4
At longer distances from the reflecting surface, the only difference you will measure is some decrease in intensity, as you said in your Opening Post (OP). But, measure the sound intensity very close to the reflecting surface...expect a surprise!

“Sound intensity near a hard surface is enhanced because the reflected wave adds to the incident wave, giving a pressure amplitude that is twice as great in a thin "pressure zone" near the surface. This is used in pressure zone microphones to increase sensitivity. The doubling of pressure gives a 6 decibel increase in the signal picked up by the microphone.”
http://hyperphysics.phy-astr.gsu.edu/hbase/sound/reflec.html
 
  • #5
for your question! Reflection of sound is a fascinating topic and there are definitely some interesting properties to consider when it comes to changes in frequency, intensity, wavelength, and velocity.

First, let's talk about the reflection of sound waves. When a sound wave hits a flat wall, it will bounce off and travel back in the opposite direction. This is known as reflection. The angle at which the sound wave hits the wall is called the incidence angle, and the angle at which it bounces off is called the reflection angle. The incidence angle and the reflection angle are always equal.

Now, to address your question about changes in frequency, intensity, wavelength, and velocity. The short answer is that all of these properties will remain the same after the sound wave is reflected off the wall. This is because the sound wave is simply bouncing off the wall and not interacting with any other medium that could cause changes in its properties.

However, there are a few factors that could potentially affect the reflected sound wave. One is the shape and texture of the wall. If the wall is not completely flat and smooth, it could cause some scattering of the sound wave, leading to changes in intensity and possibly frequency. Additionally, if the wall is made of a different material than the medium through which the sound wave is traveling, there could be some absorption of the sound wave, leading to a decrease in intensity.

Another factor to consider is the distance between the sound source and the wall. As the sound wave travels back and forth between the source and the wall, there could be some interference patterns that could affect the intensity and possibly the frequency of the reflected wave.

Overall, the changes in properties of a reflected sound wave will be minimal and likely not noticeable to the human ear. However, as a scientist, it is important to consider all factors and variables when studying sound and its interactions with different mediums. I hope this helps clarify some of your thoughts and please let me know if you have any further questions.
 

Related to Reflection of sound. Changes to its properties.

1. What is reflection of sound?

Reflection of sound is the phenomenon where sound waves bounce off a surface and change direction, without passing through the surface.

2. How does reflection affect the properties of sound?

Reflection of sound can affect the properties of sound in several ways. It can change the loudness, direction, and quality of the sound. It can also cause echoes and reverberation.

3. What are some factors that can affect sound reflection?

The type of surface, shape of the surface, and distance between the sound source and the reflecting surface can all affect sound reflection. The material of the surface, temperature, and humidity can also play a role.

4. Why is sound reflection important?

Sound reflection is important for various reasons. It helps us to hear and understand sounds from different directions. It also plays a crucial role in creating a sense of depth and space in music and other audio productions.

5. Can sound reflection be controlled?

Yes, sound reflection can be controlled through the use of sound-absorbing materials, such as acoustic panels, to reduce echoes and reverberation. The shape and design of a room or space can also be optimized to control sound reflection.

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