What Are the Physics Behind Exponential Horns and Air Expansion?

AI Thread Summary
The discussion focuses on understanding the physics of exponential horns, specifically how volume velocity behaves at the mouth compared to the throat when driven by a speaker. It highlights that as air passes through the horn, its density decreases due to expansion, even at subsonic velocities. The participant seeks affordable methods to validate these concepts, given limited access to literature. A suggested resource for further exploration is a website dedicated to brass acoustics. The conversation emphasizes the relationship between volume velocity, air expansion, and the physics underlying horn design.
HengHY
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I am trying to understand the physics of an exponential horn. I got most of my references online and according to the Horn Physics by Martin King, the volume velocity at the mouth is greater than the applied volume velocity at the throat (the horn is driven by a speaker/buzzer).
This is what i think
Volume velocity = velocity*cross sectional area
If this is true then the air expands when it passes through the horn (the air density decreases). Can this be true even though the velocity is subsonic?
Any possible cheap method to justify that? I have limited books to read.

Cheers
 
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Hi HengHY! :smile:

A good resource for musical instrument science is the australian site http://www.phys.unsw.edu.au/jw/brassacoustics.html" :wink:
 
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