How to determine harmonic number

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Homework Help Overview

The discussion revolves around determining the harmonic numbers and frequencies for a pan flute constructed from pipes of varying lengths. The original poster is unsure about how to find the harmonic numbers necessary for calculating the frequencies of the pipes, which are intended to be used as a percussion instrument.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the concept of harmonic numbers and their relationship to the lengths of the pipes. Some express confusion about whether to assign harmonic numbers based on the length of the pipes, while others suggest that harmonic numbers are simply integers (1, 2, 3, etc.) that can be applied to the formula for frequency.

Discussion Status

There is a mix of uncertainty and clarification regarding the definition of harmonic numbers and their application in the context of the project. Some participants provide guidance on how to compute the fundamental frequency using the formula, while others emphasize the independence of each pipe's length in determining its frequencies.

Contextual Notes

The original poster notes a lack of resources, such as textbooks or class notes, to explain harmonic numbers, which adds to the confusion in the discussion. There is also mention of the teacher's expectation regarding the project, which may limit the scope of questions allowed.

Nickod777
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Homework Statement



I have 8 pipes for a school project taped together to make a pan flute, they are 7, 9, 11, 13, 15, 17, 19, 21 inches... 1 inch diameter each one. I have to find the frequency of each one, but I'm not sure what the Harmonic numbers are. It is an open-ended instrument. I plan to use as a percussion instrument, using my hand, hitting the ends of the pipe to create sound.

Homework Equations



F = Hn * V/2L
F: frequency
Hn: Harmonic number
V: speed of sound traveling through pipe assume 343 m/s
L: length of pipe sound is traveling through

The Attempt at a Solution



I'm not sure how, as I do not know how to find the harmonic number, my teacher just gave us a project to make a pvc pipe instrument and a formula for Open-ended, stringed, and closed instruments. The teacher does not expect questions on anything...

Not sure how to attempt without harmonic numbers...
 
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I am not sure about what you are trying to do, but looking at that formula, I do not see a problem in just plugging integers to compute the frequencies for each pipe. Hn=1,2,3...
 
I just don't know what Harmonic numbers are. I didn't know whether to make the smallest pipe 1 or the longest pipe 1.. I need to use that to figure out the frequency of each pipe so that I can then determine the note.

Sorry I can't really provide much information, but all I was looking for was a good explanation as to what harmonic numbers are. We don't have a textbook or anything in notes and such to explain harmonic numbers.

But I think I get it. longest pipe should be lowest number and smallest pipe longest number. Since the smaller it is, the higher the frequency I believe... (I don't know anything about notes, waves, harmonics, etc.)
 
Last edited:
Nickod777 said:
I just don't know what Harmonic numbers are. I didn't know whether to make the smallest pipe 1 or the longest pipe 1.. I need to use that to figure out the frequency of each pipe so that I can then determine the note.

Sorry I can't really provide much information, but all I was looking for was a good explanation as to what harmonic numbers are. We don't have a textbook or anything in notes and such to explain harmonic numbers.

But I think I get it. longest pipe should be lowest number and smallest pipe longest number. Since the smaller it is, the higher the frequency I believe... (I don't know anything about notes, waves, harmonics, etc.)
The harmonic numbers are 1,2,3... for all pipes they are not determined in any way on the length of the pipe. So you can compute the fundamental frequency i.e Hn=1 for each of the pipes just by using f=v/(2L). If you need the other harmonics just plug Hn=2,3,... For each pipe you get 1 fundamental and a series of harmonics.
 
From each pipe you can get a fundamental note and, potentially, higher harmonics. From the OP, it seems to me that all you care about are the fundamentals, which you can compute from the formula you have, setting Hn=1. The length of each pipe dictates its fundamental and higher harmonics independently of the other pipes.
If you want to learn more about harmonics anyway, try http://www.physicsclassroom.com/Class/sound/u11l5c.cfm.
 

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