sound properties

[Dave Gumbart]

Well, only of mild interest, perhaps, but I got out my mando last night to play a bit before bedtime. I may not have the best ear, but, geez, right away the sound I heard was not that sharp (and, no, it wasn't my mediocre playing). After playing a few more seconds, I realized the distortion was due to the ceiling fan whirring away directly overhead. Sort of like talking directly into a fan and having your voice "vibrate." I took a few steps away, and everything was back to normal. Interesting that a fan, even at a relatively slow speed, could move the air sufficently to cause a distortion in the sound. If I play under the fan again, I'll just have to learn some garage band tunes and just wail away. At least now I can use an excuse for the mediocre playing "hey, I think the air's moving too fast around here."

[John Flynn]

I don't think what you experienced is due to air movement exactly. You can play in the wind and not have that problem. My instructor pointed out the ceiling fan problem to me about a year ago. He and I are not acoustic experts, but he convinced me that the cause is the sound boucing off the fan blades as they turn. It causes an effect similar to that of a "leslie" device on a Hammond electric organ. It sounds cool on an organ, but not on a mando.

[Dave Gumbart]

Thanks for the reply Mando Johnny. That makes good sense, since even a few feet away, without the sound distortion, there is probably a similar amount of air moving - just nothing to bounce off of. And you are right - it does not sound cool, even if the fan is. Cheers.

[250sc]

The room your in and where you stand in it can make a big differance in the sound of your instrument. Try standing in a corner of a room or stand about a foot from a wall (facing it) and you should notice differances in the sound.

Last weekend I was playing my guitar in a barn and found that if I stood directly in the center of the area the bass notes got huge. I stayed there since there wasn't a bass player at the time.

[mort]

When ceiling fans were in the performance area, I usually ask for them to be turned off. I find it very difficult to tune when you get the reflected sound off of them it sounds like you are out of tune. They give that vibrating kinda sound. I always find it slightly amazing that on stages built for bluegrass you will see those ceiling fans installed. Some blowers WAY back from center are much better.

[sunburst]

Some years ago I was having a particularly hard time trying to get in tune at a jam session, and concluded it was the ceiling fan that was cousing the trouble.

Here's what I think happens: (pure speculation) The sound is echoing off of the fan blades. The blades are moving, so, some of them are coming toward you, and some of them are going away from you. The Doppler effect causes you to get different pitches echoed back to you. It's like a train whistle or a car horn that seems to change pitch as it goes by, but it's happening continuously when the fan is running. Make sense?

[TonyP]

Yes! That's it John! I agree with MJ about the blades but the dopler effect is the missing piece. Brilliant.... We're out here in the badlands of CA where it seems like you can't live without a fan but it is so annoying when trying to get in tune we'd rather sweat.

[Lee]

Sound waves propagate using air as the vibrating medium. They move much faster than wind so this would have little affect. Also, wind isn't moving in a cyclic or oscillating pattern as is sound. My personal opinion is that the reflection off the blades is certainly a factor but since a fast moving fan oscillates the air it might cause wave interference, and I wouldn't discount this affect from the larger equation.