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Announcements: Homework 9: only one third (!) turned it in. EXTENDED to next Tuesday Note: to find frequencies of tones needed in to answer the asignment, either look it up on p. 153 of Backus, or calculate relative to the nearest A (440, 220 Hz etc) using the tempered semitone ratio (1.05946) Paper outline due Third exam is canceled (but will provide exam if anybody requests it) Recitals: Beatriz (trombone) Friday 7:30 St. Frances House Helen (viola) Saturday 2:30 St Frances House Gayle (piano) winner Beethoven Piano Competition D-minor Sonata Op. 31 #2 3:30 Sun Morphy Greg, Daniel (Tuba): Tuba and Euphonium Ensemble 2 pm Sat. Mills Concert Band 2 pm Sunday Mills Friday 7:30 Music Hall acapella concert Elise (Bassoon) Saturday May 4 at 1 pm St. Frances House Andrea? Others?
Physics 371 April 25, 2002 Acoustics for Musicians • Reed Instrum. (summary) • difference cylindrical/conical • what partials in tone? • importance of cutoff frequency • Bowed String Instruments • construction • rocking motion • plate resonances • “breathing” mode
oboe, bassoon, clarinet who can bring bassoon?
lowest total bell note length diam Clarinet: D3 67 cm 6 cm Soprano Sax: A3b69 cm 6 cm Oboe: D3 64 cm 4 cm profiles of reed instruments (vert scale enlarged 3-times)
Difference between cylindrical bore and conical bore (same L) 1. cylindrical bore (Clarinet) lower by nearly an octave than conical bore (Oboe) of same length 2. Clarinet overblows to the twelvth, Oboe to the octave thus Clarinet needs 7 more tone holes
If Clarinet is a cylindrical closed pipe, simple theory says there should be only odd partials...... • explanation: • clarinet differs from simple closed pipe: • has tone holes • has tapered mouth piece • has bell • higher modes are shifted • and broad - see next slide.... for all instruments the spectrum changes as we ascend the scale (high tones - fewer partials)
The dots mark all multiples ofthe fundamental frequency even if higher modes are shifted, the partials are still exact multiples since excitation is periodic Clarinet resonance curve (all tone holes closed) 3 8 6 5 2 4 7 frequency (Hz)
Timbre depends on profile of instrument. • example: • Oboe and Sax are both conical • reed instruments but • Sax has : (see picture next slide) • large opening angle, large bell • -> lower freq cutoff • large tone holes of Sax • loud! strong low partials • Oboe has: • small opening angle, small bell • -> high freq cutoff • small tone holes • soft, B3b A3b Soprano Sax
Saxophone instrument designed (rather than evolution)
see papers by Carleen Hutchins is there a detectable difference between Strads and other violins?
Strads other old Italian masters Tuning of the lowest resonances of different violins