Sound waves affected by wind/sound waves in materials

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SUMMARY

Sound waves in air are significantly affected by wind, as the motion of the medium (air) adds to the sound's motion vector. The speed of sound in brass is 6 to 16 times faster than in air, depending on the brass's grain. When sound travels through materials like rail, it is more efficient than in air, but transferring sound from the rail to the air presents challenges due to energy reflection at the steel-air boundary. To accurately measure sound speed in a rail, placing an ear against it is recommended for optimal hearing of the sound wave.

PREREQUISITES
  • Understanding of sound wave propagation in different media
  • Knowledge of the speed of sound in air and solids
  • Familiarity with wave behavior at material boundaries
  • Basic principles of sound energy transfer
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  • Research the speed of sound in various materials, including metals and gases
  • Explore the effects of wind on sound propagation in air
  • Study wave behavior at boundaries, focusing on energy reflection and transmission
  • Learn about experimental methods for measuring sound speed in solids
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Acoustics researchers, physics students, engineers working with sound transmission, and anyone interested in the principles of sound wave behavior in different media.

aspodkfpo
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Homework Statement
Are sound waves affected by wind?
Sound waves in materials, listen by ear?
Relevant Equations
n/a
Are sound waves in air affected by wind? If the medium of the air propagation travels forward, does the sound also travel faster or is the sound simply vibrations in positions of space which disregard the movement of its medium.
Would a transverse wave similarly move faster?

If I was to attempt to record the speed of a wave (e.g. smashing the metal with a hammer) traveling in a metal over a distance of 1km. Would I have to press my ear against the metal to hear it, or would I hear it while standing as well?
If I stand would I hear both the wave in air and the metal, or only the air?
 
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Sound waves are affected by wind.
The speed of sound is a speed within the media (air).
So if the media is moving, that motion vector is added to the motion vector of the sound.

The speed of sound through brass will be 6 to 16 times as high as it is in air - depending on the grain of the brass.

It you strike a bell, you are hearing sound in the bell transferred to the air and then to your ear.
 
Last edited:
.Scott said:
Sound waves are affected by wind.
The speed of sound is a speed within the media (air).
So if the media is moving, that motion vector is added to the motion vector of the sound.

The speed of sound through brass will be 6 to 16 times as high as it is in air - depending on the grain of the brass.

It you strike a bell, you are hearing sound in the bell transferred to the air and then to your ear.
If I strike the train tracks, and put my ear against it, do I hear the speed of transmission through the material?
 
.Scott said:
It you strike a bell, you are hearing sound in the bell transferred to the air and then to your ear.
Yes, but in the scenario in this thread you have the option of also hearing sound which has covered most of the distance by rail. That will arrive at a different time.
(I'm assuming @aspodkfpo means that you are listening next to the rail some distance from where it was struck.)
 
haruspex said:
Yes, but in the scenario in this thread you have the option of also hearing sound which has covered most of the distance by rail. That will arrive at a different time.
(I'm assuming @aspodkfpo means that you are listening next to the rail some distance from where it was struck.)

So the sound travels through the rails while also spreading to nearby air, and when it is close to you, you hear the sound via air?
 
aspodkfpo said:
So the sound travels through the rails while also spreading to nearby air, and when it is close to you, you hear the sound via air?
When what is close to you, the original impact or the rail?
The sound will travel better along the rail than in air, partly because it is not getting spread out over a sphere. By the same token, it doesn't travel well from the rail into the air, so you can be a long way from the impact by rail, but then need to be close to the rail to hear it.
 
haruspex said:
When what is close to you, the original impact or the rail?
The sound will travel better along the rail than in air, partly because it is not getting spread out over a sphere. By the same token, it doesn't travel well from the rail into the air, so you can be a long way from the impact by rail, but then need to be close to the rail to hear it.
when the rail is close
 
aspodkfpo said:
when the rail is close
Ok
 
haruspex said:
Ok
so I am right about that?
 
  • #10
aspodkfpo said:
so I am right about that?
Unless you lay your head on the rail you can only hear the sound by air as the last hop. And the sound always starts in the rail, so there are always the two stages.
If you are close to where the rail is hit, there's a lot of sound energy in the rail, so despite the hurdle of transferring it to air you hear it well. But it doesn't carry as well in air as it does along the rail, so you can be a long way from the strike point as long as you are close to the rail.
 
  • #11
haruspex said:
Unless you lay your head on the rail you can only hear the sound by air as the last hop. And the sound always starts in the rail, so there are always the two stages.
If you are close to where the rail is hit, there's a lot of sound energy in the rail, so despite the hurdle of transferring it to air you hear it well. But it doesn't carry as well in air as it does along the rail, so you can be a long way from the strike point as long as you are close to the rail.

So I suppose laying your head on the rail is much more accurate for trying to experiment for the speed of a sound through the rail?

Why is there a hurdle of transferring it to air? Doesn't the rail just vibrate, and the surrounding air particles vibrate around it?
 
  • #12
aspodkfpo said:
So I suppose laying your head on the rail is much more accurate for trying to experiment for the speed of a sound through the rail?

Why is there a hurdle of transferring it to air? Doesn't the rail just vibrate, and the surrounding air particles vibrate around it?
Change of medium is always a bit of a barrier for a wave, including light. The bigger the change, the greater the barrier.
Consider a wave front radiating out from the centre of a solid cylinder (rail) and reaching the outer surface. Most of the energy will be reflected back in, and only a small proportion transferred to the air. That's why the rail continues to ring, and why the sound can go a long way along the rail with only modest attenuation.
 
  • #13
haruspex said:
Change of medium is always a bit of a barrier for a wave, including light. The bigger the change, the greater the barrier.
Consider a wave front radiating out from the centre of a solid cylinder (rail) and reaching the outer surface. Most of the energy will be reflected back in, and only a small proportion transferred to the air. That's why the rail continues to ring, and why the sound can go a long way along the rail with only modest attenuation.

How is most energy reflected? is there some boundary, what causes this boundary?
 

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