Ceiling Fans and "Leslie" Effect

[Wiggy]

Does this bother anyone else? The sonic flutter makes it nearly impossible to tune my instruments. When playing, it creates a not-so-subtle high-speed wah effect for the uke and the voice. When I seriously want to play and listen, I have to turn it off.

(I have one in every room in the house except the kitchen and basement. Yes, the garage has one, too.)

 

[oldjazznut]

Is it the blades or motor making the sound? Does it happen with all of the fans? May be your sound is refecting off the ceiling and getting chopped up by the fan. Have you ever talked into a box fan or desk fan? It adds a buzz to your voice. Another example is the rotating disks in vibraphone resonators, adding their "wah-wah" effect.

You could try reversing the direction. In the summer they work best pulling cool air up from the floor. Wintertime better blowing warmth down. Either way helps mix the air.

I've got ceiling fans in every room except the bathroom. I've never noticed any effect from them, but I rarely run them above Low.

 

[Joe T]

Hey Wiggy. I too have ceiling fans in most of the rooms. When the room that I generally play in ceiling fan is on medium or higher the flutter is terrible. If I'm in there to actually play, the fan has to go off. This is an 8'x10' room and there is something about the rooms acoustics that creates that warbling sound with the fan on. FWIW, replacing the ceiling fan with a totally different brand didn't change the warble. When the original went bad, I had hoped the new fan with different blades would eliminate it.

 

[kkimura]

A fan with an odd number of blades would break up the resonance.

 

[Kenn2018]

I was going to ask if your fans have 4 or 5 blades? But, what kkimura said.

 

[oldjazznut]

I have 2 five foot, five blade Island Breeze (name?) fans. I have 4 four foot, four bladed Hunters. Don't hear a difference, but the Island motors hum slightly. Maybe from the larger load on them, or just not Hunter's quality.

 

[Ukecaster]

Def get the chopper effect when playing under a ceiling fan, which makes sense, since the sound waves are getting chopped up by the fan blades. I just turn it off, or try to use it as a metronome, and jam with it.

 

[Wiggy]

Is it the blades or motor making the sound?... May be your sound is refecting off the ceiling and getting chopped up by the fan.

It is not motor noise. The flutter ("chopper effect," as accurately described by Ukecaster) is caused by sound reflecting off the blades at a moving (sweeping) radial angle. All are 5-blade, except for one 3-blade.

As a metronome... I put a piece of painters tape on the end of 1 blade so I could count revs/second. On slow, a guess-timate was 2 rev/sec x 5 blades resulting in about 10 flutter "thumps" per second. That could produce a beat frequency (probably not an accurate term, but close) depending on how you mentally divide it up.

Oh, the things we perceive and fixate on. Good thing I can turn it off.

Consider the top "twin" horn on a Leslie.

Understanding The Leslie Effect

The Leslie speaker effect can be heard on countless hit records. But how does it work, and why do we like hearing it so much? Joe Albano explains all.

ask.audio

 

[dancephoto]

FWIW I play a free-reed wind blown instrument (accordina) and overhead fans cause the same problem.

 

[Jerryc41]

Does this bother anyone else? The sonic flutter makes it nearly impossible to tune my instruments. When playing, it creates a not-so-subtle high-speed wah effect for the uke and the voice. When I seriously want to play and listen, I have to turn it off.

(I have one in every room in the house except the kitchen and basement. Yes, the garage has one, too.)

Wait for winter to play your uke.

Yes, I have experienced strange effects involving fans and sound, although I don't have ceiling fans.

 

[Mfturner]

Lol, I hadn’t noticed it before, and now I cannot unhear it.

I do notice it more strongly when I play more loudly, my guess is that you hear more reflected room sound when you play loudly, whereas the sound is more nearfield when played softly.

 

[Wiggy]

Lol, I hadn’t noticed it before, and now I cannot unhear it.

Sorry...

 

[Joe T]

A fan with an odd number of blades would break up the resonance.

I was going to ask if your fans have 4 or 5 blades? But, what kkimura said.

All my fans have 5 blades.

 

[Wiggy]

I sort of get what kkimura said about 4 blades, as 2 blades will always be reflecting but at opposite angles. Maybe?
It's kind of like the old 70s Bose 901 or 301 diagrams showing direct vs reflected sound, except the reflection is moving (rotation).

A poor man's Phaser? Do I need a foot switch for the fan? Hmm...

 

[kkimura]

A poor man's Phaser? Do I need a foot switch for the fan? Hmm...

You may have something there. Try a second ceiling fan identical to the first only rotating in the opposite direction. The two fans will cancel each other out.

 

[Wiggy]

The true Leslie effect:

A friend of mine in MO has this rig in his LR, and man can he wail!
Hammond B3, with a Leslie cabinet on top of a Dynacord 18" sub that is powered by an Ampeg 500 Bass guitar amp (that's it, way on top.)

He will only play in his original "pointy" cowboy boots, gotta be able to accurately all hit those bass pedals.

 

[Yukio]

It is not motor noise. The flutter ("chopper effect," as accurately described by Ukecaster) is caused by sound reflecting off the blades at a moving (sweeping) radial angle. All are 5-blade, except for one 3-blade.

As a metronome... I put a piece of painters tape on the end of 1 blade so I could count revs/second. On slow, a guess-timate was 2 rev/sec x 5 blades resulting in about 10 flutter "thumps" per second. That could produce a beat frequency (probably not an accurate term, but close) depending on how you mentally divide it up.

Oh, the things we perceive and fixate on. Good thing I can turn it off.

Consider the top "twin" horn on a Leslie.

Understanding The Leslie Effect

The Leslie speaker effect can be heard on countless hit records. But how does it work, and why do we like hearing it so much? Joe Albano explains all.

ask.audio

Cool info!

 

[Wiggy]

In your younger days, did you ever speak in front of a fan just to hear the funny chopped sound?
Only the frequency PPS (paddles per second) and proximity have changed.