How does a trumper/horn work?

[PugwasHDJ80]

have played the trumpet for years, but I have no idea what causes it to amplify the breath out of my lips?

So how does a horn amplify noises? a trumpet has a significantly higher sound pressure than anything I can produce, but as far as I can see, it doesn't add extra energy anywhere?

Its been bugging me for a week or so now, and googling it either gives very simple answers, or hideously complex answers- neither of which seem to help!

Edited by PugwasHDJ80 on Thursday 26th June 13:15

[ewenm]

I don't know but my gut answer is "resonance" - you set up standing waves in the tubing that combine to produce the louder sound.

[Halmyre]

ewenm said:

I don't know but my gut answer is "resonance" - you set up standing waves in the tubing that combine to produce the louder sound.

Resonance, and IIRC the flared mouth 'impedance matching' the resonant energy to the outside world. I'm not sure how the 'impedance matching' bit works with non-flared instruments like a flute or piccolo, though.

[rich83]

http://www.phys.unsw.edu.au/jw/brassacoustics.html

You might have seen that already.