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Can you hear the wind blow?
September 7, 2012 6:42 AM   Subscribe

Can wind affect sound waves?

I was sitting on my deck one night when both my SO and I heard the local college marching band practicing about a mile or two away. She said something to the effect that the wind must be carrying the sound. I laughed it off and said that wind does not affect sound. She persisted that it does. I end up Google searching and have found several different takes on the question.

So I ask any metafile auditory-climatologist out there; if wind is blowing away from me, does the sound of the marching band decrease vs. increase in volume if its blowing toward me?
posted by amazingstill to Science & Nature (8 answers total) 3 users marked this as a favorite
 
Just a guess, but considering air is the medium through which the sound waves have to travel, if the wind is blowing away from your (towards the sound), then the sound will have to travel through more air, which would mean it would be less loud, and vice versa.
posted by Grither at 6:52 AM on September 7, 2012


It could -- air movement and temperature have a variety of effects on sound transmission. However, the speed of sound is a lot higher than the speed of the wind (I would hope), so movement of the medium probably doesn't have a lot of effect on transmission speed or distance. Temperature refraction is probably it, causing sound to "bend" through different temperatured air, sort of like a mirage or a prism, focusing distant sound around obstacles and to your ears. But, remember wind is caused by temperature and pressure differences, so it may be a related symptom, not necessarily the cause of the sound distance gains.
posted by AzraelBrown at 6:52 AM on September 7, 2012 [1 favorite]


"away from you" skip that 'r' in there.
posted by Grither at 6:52 AM on September 7, 2012


Yes.

Not that the sound is wafted along on a zephyr to remote locations, but that the humidity and windspeed can affect how well or not sound travels.
posted by gjc at 7:42 AM on September 7, 2012


Can wind affect sound waves?

Yes. Yes yes yes yes yes yes yes. I haven't got any "SCIENCE!" links at the moment to back it up, but I've been doing live sound for close to twenty years, so literally hundreds of gigs outside in varying wind conditions, and in general your hypothesis is correct - if the wind is blowing from the band towards you it will seem louder than if the wind is blowing away from you towards the band.

Temperature & humidity can also affect how far sound travels.

However, "a mile or two away" is a bit far to be explained solely by wind, I think. I strongly suspect there's some additional factors in play - most likely some kind of reflection off buildings between your deck and the campus that is essentially "focusing" the sound in your direction and/or the possibility that the sound waves are "bouncing off" a layer of air above you that is a different temperature and density.
posted by soundguy99 at 7:49 AM on September 7, 2012 [2 favorites]


As I understand it, windspeed refraction plays a major part. (That's probably not the right term.) Near the ground, the wind is moving slower, so sound travels at a different speed in that layer. The difference is small, but the effect is much like a change in refractive index (positive or negative depending on whether you're going against the wind), and over a longish distance this can duct sound down or up.
posted by hattifattener at 11:19 AM on September 7, 2012


As a kid, I used to love singing or talking into an electric fan because of the way it would change the sound of my voice. I suspect that the wind can have significant effects on how sound travels.
posted by surenoproblem at 2:11 PM on September 7, 2012


Most definitely. There is a major highway @ 2km from my house, directly visible. Under normal conditions (highway is upwind) it's audible as dull white noise, but when the wind shifts & blows toward the highway the neighborhood is noticeably quieter. Evidently the reason is not that the sound 'carries' better downwind, but that the turbulence of the upwind motion disrupts the air as an effective transmission medium. See this and this.
posted by TDIpod at 6:41 PM on September 7, 2012


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