Why do open holes in air instruments act as pressure nodes?

  • #1
200
3
Just out of curiousity, why is this?

I'm reading this page right here:
http://newt.phys.unsw.edu.au/jw/fluteacoustics.html#registerhole

A dark hole on the flute means the button is closed, and each white hole means the button is open (open to atmospheric pressure).

You can see from the diagram that for every open hole, a node is formed in the corresponding wave. What about this exposure to atmospheric pressure makes this happen?

Thanks.
 

Answers and Replies

  • #2
907
88
I don't interpret it that way. It mentions in the article that opening the holes is effectively making the instrument shorter, so essentially moving the node to this end point.
 
Last edited:
  • #3
olivermsun
Science Advisor
1,244
118
The "shortening" interpretation is consistent with the "node" interpretation. After all, what's significant about the "end" of the instrument, except that it's the place where the oscillating air column is open to the atmosphere? At that location, the pressure is essentially equal to ambient, or "zero," pressure.
 

Related Threads on Why do open holes in air instruments act as pressure nodes?

Replies
10
Views
906
Replies
1
Views
1K
Replies
13
Views
43K
Replies
4
Views
2K
Replies
1
Views
806
Replies
1
Views
900
  • Last Post
Replies
7
Views
4K
Replies
7
Views
920
  • Last Post
2
Replies
35
Views
9K
Top