What Are the Physics Behind Exponential Horns and Air Expansion?

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    Exponential Physics
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SUMMARY

The discussion focuses on the physics of exponential horns, specifically referencing the work of Martin King on horn acoustics. It establishes that the volume velocity at the mouth of the horn exceeds that at the throat, driven by a speaker or buzzer. The conversation highlights the relationship between volume velocity, air expansion, and density reduction, even at subsonic velocities. Participants suggest resources for further understanding, particularly in the context of musical instruments.

PREREQUISITES
  • Understanding of volume velocity in acoustics
  • Familiarity with the principles of air density and expansion
  • Basic knowledge of subsonic and supersonic flow dynamics
  • Access to resources on horn physics, such as "Horn Physics" by Martin King
NEXT STEPS
  • Explore the mathematical relationship between volume velocity and cross-sectional area in exponential horns
  • Research the effects of air density changes on sound propagation
  • Investigate practical experiments to measure volume velocity in horns
  • Study the acoustic properties of brass instruments through the recommended UNSW resource
USEFUL FOR

Acoustics researchers, audio engineers, musicians interested in instrument design, and anyone studying the physics of sound propagation in horns.

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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