Air-Flow and Standing waves?

[bluseminole]

Originally Posted by jeff92k7

But how much of that is caused by the airflow and how much of that is caused by the sound waves hitting the fan blades themselves. I would argue that what you are hearing is the sound of the sax going up and hitting the fan blade one instant, then all the way up to the ceiling the next, and so on. In that case, it's not the movement of air that is causing what you hear. It is the fact that sound waves are reflecting off of a moving object.

You can hear this effect by speaking into the front or back of a box fan, or any other fan with a safety guard on it. (Never, ever get that close to a moving ceiling fan or any fan without a safety guard on it). In this case, you will note that there is only a very minor difference, if any, in sound between speaking into the front of the fan as opposed to the back. For airflow to have a noticeable effect, there would have to be a noticeable difference between the front and the back since sound is moving in opposite directions on each side.

I should have been more clear and noted that in my first post but since the question was about airflow affecting sound waves and not how the fan blades interact with fan blades, I failed to do so. I stand by my original statement that the moving air will have very little effect on the sound waves - standing or otherwise.

I don't know much about acoustics, but with all respect, I would have to agree that airflow does make a difference. When I play piano (a grand), it doesn't matter whether its open or closed, if the ceiling fan at the other end of the room is on, the sound seems to bounce all over the place and have the kind of "wahWAHwahWAH" effect, similar to the one you get when you talk right into an oscillating fan. It's quite noticeable when the fan is on high; turn the fan on low, and the effect disappears.

I don't know