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I know this has been discussed ad nausium but looking back through the forum I beleive that the ceiling fan effect on concertina sound was never fully explained. The explaination is that as the fan rotates it pushes a column of air down away from the fan past both my ears and then past the concertina. The sound waves coming from my concertina then have to travel against that moving column of air up toward my ears. Because the sound waves have to travel against the air flow, the pitch is generally decreased. It is like hearing a train whistle on a train moving away, producing a lower sound. Because the train is moving away, the sound waves are spread out. Likewise the conceritina sound waves are spread out as they are moving through air which is moving away from my ears, pushed by the fan. The speed of the fan would determine the degree of the effect.

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I know this has been discussed ad nausium but looking back through the forum I beleive that the ceiling fan effect on concertina sound was never fully explained.  The explaination is that as the fan rotates it pushes a column of air down away from the fan past both my ears and then past the concertina.  The sound waves coming from my concertina then have to travel against that moving column of air up toward my ears.  Because the sound waves have to travel against the air flow, the pitch is generally decreased.    It is like hearing a train whistle on a train moving away, producing a lower sound.  Because the train is moving away, the sound waves are spread out.  Likewise the conceritina sound waves are spread out as they are moving through air which is moving away from my ears, pushed by the fan.  The speed of the fan would determine the degree of the effect.

Jim

 

Your explanation is true for any musical instrument. However, as far as I understood from previous discussions, the "ceiling fan effect" was only observed with concetina's :huh:

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I'm not convinced by this explanation, I'm afraid. The reason is that if there was a column of air pulsing past my ears and my concertina fast enough to produce this effect, surely I would notice it? When experiencing a draft of air from a fan all I can feel is a continuous stream of air, and the effect is audible whether I am in the airstream or not.

 

Here is a more extreme example. Here at my home we have a conservatory with a ceiling fan. I can sit in the neighbouring room playing with the door open and obtain the effect. I don't even have to be in line of sight of the fan for it to happen. If any moving air at all reaches me and my concertina from the fan then any variation in speed would long ago have been smoothed out.

 

I would tentatively sugest either sound reflected from the moving blades of the fan or sound slowed as it moves the pulsing column of air prior to be reflected back to my ears (and through the air a second time) by the walls. But I can see problems with both of these explanations also. Still, good try!

 

Chris

 

Edited to add PS: the effect does not change regardless of your orientation to the fan. If the effect were due to the air moving past you then your orientation would be significant.

 

PPS I think I will submit this to the Last Word column at New Scientist, and seee what the eggheads make of it.

Edited by Chris Timson
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I'm thinking of adding a new section to the Concertina FAQ, thus:-

 

Concertinas and Fans

 

We know, strange, isn't it? We all wish we knew why it happens, but we don't. It's the same with the strange bell-like effect you get if you swing a concertina round while you're playing. If anyone can crack these phenomena then I for one would love to see them win a Nobel prize!

 

Chris

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.... It's the same with the strange bell-like effect you get if you swing a concertina round while you're playing.

Chris

 

I thought that was just plain Doppler ... :unsure:

 

As for ceiling fans, how about standing waves with a wavelength just the right size for a concertina ... hmmm.... standing waves have more to do with the room dimensions that the length/speed of fan blades. Matbe not then (but has anyone tested this with a range of concertina diameters :D )

 

and finally... just when you're all totally fed up with ceiling fans, when you get the bottom of the page, google greets you with

 

Ceiling Fans

Wide range of Ceiling Fans Quick Free delivery. 10 yr warranty

Ceiling Fan Winter Sale

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Chris J.

Edited by spindizzy
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I've always thought that it was something to do with beat frequencies and concertinas seem more prevalent to these causing interference because of the large range of harmonics that are generated by free reeds, traditional concertina reeds in particular.

 

This is also the main reason for advising that chords are spread across as wide a range as possible to get a better sound.

 

We really need someone to do some research on the specral analysis of concertinas and of ceiling fans and compare the results.

 

Robin Madge

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  • 2 weeks later...

I've submitted the following question to the Last Word column of the New Scientist magazine. Let's see what the boffins make of it.

I play the concertina (think musical threepenny bit), the small six-sided member of the accordion family invented by the Victorian scientist Charles Wheatstone. It is a well-known phenomenon among players that if you play a concertina in the vicinity of a rotating fan you get a strong vibrato effect. There's been a lot of discussion over the years among players as to its cause, most relating back to the Doppler effect in some way, but nobody has ever really come up with a convincing explanation of the phenomenon. Can anyone explain it?

Chris

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It is a well-known phenomenon among players that if you play a concertina in the vicinity of a rotating fan you get a strong vibrato effect. There's been a lot of discussion over the years among players as to its cause, most relating back to the Doppler effect in some way, but nobody has ever really come up with a convincing explanation of the phenomenon. Can anyone explain it?

I hate to criticize a friend, Chris, but I think you've just done a major disservice to the whole subject. What I suspect is that you will get lots of "explanations", but none of them based on actual measurement. However, people will in the future claim (improperly, but so what?) that "New Scientist reported [blah, blah, blah]," and that therefor the matter is settled.

 

What's more, I wouldn't even describe the effect as "vibrato", but more as "rasping".

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Jim, I'd say "rasping" is how it effects me, but "vibrato" is what it is although unpleasantly fast and undulating unevenly.

To me, "vibrato" implies evenness, and I doubt that any violinst or singer could achieve the same effect using the vibrato technique. Do we even know that it's truly a variation in pitch, and not a variation in tone quality or volume, or (as I suspect) a non-smooth distortion (chopping?) of the waveform? Have any of us viewed the resulting soundwaves on an oscilloscope?

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I agree Jim that most of us want to think of vibrato as even and pleasant. The term however is used to discribe what is vibrating, shaking, quivering and in the case of the human voice it is not really a technique but a natural frequency at which individual instruments resonate.

 

Sidebar, but I think it's cool:

Violinists developed a techinque to approximate the vibrato of the human voice starting in the late 1700's. Vocalists developed a techinque to approximate an absence of vibrato, it is conjectured, in response to the sound produced by early bowed instruments in the middle ages.

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Sidebar, but I think it's cool:

Violinists developed a techinque to approximate the vibrato of the human voice starting in the late 1700's.  Vocalists developed a techinque to approximate an absence of vibrato, it is conjectured, in response to the sound produced by early bowed instruments in the middle ages.

I have my doubts. Too many traditional singing styles in too many parts of the world have no vibrato. Ditto with flutes. (I've been specifically told to curtail my own vibrato when playing traditional musics.) My understanding has been that the heavy-vibrato singing style was a specific Italian tradition, until that style became the rage throughout Europe and so became the standard for "classical" music.

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Granted Jim, and I should have stipulated the influence of European musical development you attribute to Italy (I'm sure they would agree gleefully and not without evidence) as to my sidebar.

 

However it is my belief that as many traditional musical cultures around the world are rooted in "vibrato" styles of singing (Tuvan throat singing or a large number of Arabic vocal traditions) as are not.

 

Conscious employment of vibrato or its absence in a singing tradition is an asthetic evolution in each culture. Vibrato as a natural frequencey within the human voice is unequivocal and varies in each adult human as to rate of undulation.

 

In the long run we agree Jim...but Chris was on solid ground in my view to call that horrid sound a concertina produces when in the presence of a fan as (and I will stipulate here) a type of vibrato. :)

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I hate to criticize a friend, Chris, but I think you've just done a major disservice to the whole subject.  What I suspect is that you will get lots of "explanations", but none of them based on actual measurement.  However, people will in the future claim (improperly, but so what?) that "New Scientist reported [blah, blah, blah]," and that therefor the matter is settled.

It may be that you don't or haven't read New Scientist? As you are in Denmark and it is a British magazine this would be a reasonable assumption. The previous track record of the Last Word column (and it has been going for a few years now) is that most of the respondents would likely be professors of accoustics who, if they cannot come up with a ready reason, are likely to take it on as a research project. It's an impressive resource. You do the column and the magazine, and me come to that, a disservice. Give them a chance!

 

Chris

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It may be that you don't or haven't read New Scientist?

I thought I had seen the New Scientist, but perhaps I have it confused with another magazine? (British and American magazines -- among others -- are often available here, on newsstands, as well as in libraries.)

 

...if they cannot come up with a ready reason, are likely to take it on as a research project.

My worry is that they may well "come up with a ready reason", without ever putting their hands on a concertina. I've seen all too many examples of this among serious, and even highly respected scientists. (I won't name names, because this is already on the border of inappropriate, and I'm not quite sure which side of the border I'm on. :unsure:)

 

It's an impressive resource. You do the column and the magazine, and me come to that, a disservice. Give them a chance!

A chance, fair enough. But not the benefit of the doubt. I will continue to doubt until I see the result. Don't want to endanger my SoCC (Society of Confirmed Cynics) membership. :ph34r:

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