I want to study about the phenomenon of reflection of pressure waves as in an open ended organ pipe. Please suggest a suitable resource? I know about the harmonics in a stretched string and I can use the analogue to find the nodes and the antinodes formed when a pressure wave passes through an open organ pipe or a closed organ pipe. However, I read the following question in a book:

A high pressure pulse was sent into a open organ pipe. What will be the nature of the reflected pulse? (high pressure or low pressure?)

And I was stumped, as I could not see physically how reflection should occur.

I searched on this site, and in a Phys.SE question, I found this link.

But I already know this analogue and this is what I primarily use for problem solving, but, I do not know how to solve uniquely for a pressure wave, i.e. without comparing it to a wave in a string.


1 Answer 1


I think The Physics of Musical Instruments (Springer Science & Business Media, 1998) by Fletcher and Rossing would be a good starting point for you.

The general physical description of sound rests on the investigation of the impedance changes on the boundaries. For example: the reflection at the end of the string is caused by the discontinuity between non-zero impedance of the string and the "infinite" (i.e. very high in real systems) impedance of the string ending. (Note: you need to think about the string as the acoustic system, not just one mechanical oscillator.)
The very same principle governs the behavior of the organ pipe, you just need to switch from mechanical impedance to acoustic impedance (or characteristic impedance).

If you are not familiar with these concepts I suggest you to read about them first and then ask a specific question.


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