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This may be out there. Like many places it has been hot so I brought a fan into my practice area. Somehow that makes my concertina sound weird especially the high notes. I even checked that I was still in tune . It is almost like everything is a little tinny. When I turn the fan off it stops.

I think this probably has an acoustical explanation. Just wondering about it

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This is well-known, although a lot of folks misinterpret it and think it has something to do with the doppler effect, which is not right.

 

What’s happening is that the blades of the fan are sending waves of compressed room air in all directions. the frequency of these waves is the inverse of the amount of time it takes each fan blade to travel to where the adjacent one was a moment ago. As each wave of compressed air encounters the concertina it affects the way that the reeds vibrate. The sound that results resembles what your voice would sound like if you shake your fist rapidly while phonating.

 

I demonstrated this to myself by accident a few years ago at Morris Dance practice. It was a hot evening and we had a fan set up. I stood playing with my back to the fan so my body blocked the waves and my playing was unaffected. At one point one of the dancers advanced toward me and at the same time I could feel the wind from the fan bouncing off his chest and the concertina briefly exhibited the effect you describe.

 

It’s called the ceiling fan effect, because it happens most commonly with ceiling fans. I once had to stop a concert at Pinewoods because an unsuspecting concertina player sat down to play right under a ceiling fan in the Camp House. We shut off the fan, and later I showed him what would have happened if he had played under the spinning fan.

Edited by David Barnert
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15 minutes ago, Stephen Chambers said:

There have been other threads about this in the past, like:

 

Never Play Next To A Fan :)

 

Unintended tremolo

 

Doppler Effect

 

15 minutes ago, Stephen Chambers said:

There have been other threads about this in the past, like:

 

Never Play Next To A Fan :)

 

Unintended tremolo

 

Doppler Effect

Thanks. somehow I had missed those posts.

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If you throw a pebble into a still pond, you will see even concentric ripples spreading across the surface.

 

If you throw a pebble into a turbulent sea, the ripples will quickly be broken and lost.

 

(Somehow, I feel the word, "Grasshopper" should appear somewhere in the above.)

 

The sound waves are being broken up and lost in the turbulence caused by the fan,

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I would be much more inclined to attribute the OP's experience to the propagation of the sound after it leaves the concertina than to the behaviour of the reeds inside, for two reasons. One is that the flow of air past the reeds depends on what you do with the bellows and would be affected very little if at all by slow movement of air outside the concertina. The other reason is that a similar effect was discussed very recently on another forum that I frequent, and in that case no free reeds were involved.

See https://www.vintage-radio.net/forum/showthread.php?t=192759

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This is an endless topic. While I encourage thoughtful discussion and anecdotes, please do not get contentious over the physical theory so we don't have to shut down a vociferous debate as in the past. Thanks.

 

Ken

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