PHYS 341 Lecture Notes - Lecture 25: Brasswind, Pedal Tone, Semitone
Document Summary
Motion of lips in trumpet + trombone embouchures. Controlled by: lip tension: acoustic pressure in instrument. Uses bernoulli effect like air reed, b/ subject to feedback from instrument. High speed movie of transparent mouthpiece by matthias bertsch, Periodic pulses of air coming from lips produces a harmonic series. 1:2:3:4 if enough of these harmonics correspond to tube resonances trumpet will sound. Bottom note of trumpet picks up the modes at 240, 360, 480 hz even though 120 hz mode is missing. 1st valve adds 12% length (2 semitones) 2nd valve adds 6% in length (1 semitone) Pressing both valves add 18% (~3 semitones) Never quite in tune b/c 3 semitone requires 19% Player has to fix by bending note. Three valves trumpet has 3 values: dropping pitch by: whole tone, semitone, three semitones in perfect world pressing values 1,2 would be identical in effect to pressing 3 but not a perfect world.
