Announcements:Homework 9: only one third (!) turned it in. EXTENDED to next TuesdayNote: 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 dueThird exam is canceled (but will provide exam if anybody requests it)
Recitals: Beatriz (trombone) Friday 7:30 St. Frances HouseHelen (viola) Saturday 2:30 St Frances HouseGayle (piano) winner Beethoven Piano Competition D-minor Sonata Op. 31 #2 3:30 Sun MorphyGreg, Daniel (Tuba): Tuba and Euphonium Ensemble 2 pm Sat. Mills Concert Band 2 pm Sunday MillsFriday 7:30 Music Hall acapella concertElise (Bassoon) Saturday May 4 at 1 pm St. Frances HouseAndrea?Others?
Physics 371 April 25, 2002
• Reed Instrum. (summary)
difference cylindrical/conical
what partials in tone?
importance of cutoff frequency
• Bowed String Instruments
construction
rocking motion
plate resonances
“breathing” mode
lowest total bellnote length diam
Clarinet: D3 67 cm 6 cm
Soprano Sax: A3b
69 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 length2. Clarinet overblows to the twelvth, Oboe to the octave thus Clarinet needs 7 more tone holes
If Clarinet is a cylindrical closed pipe, simple theorysays 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 shiftedand broad - see next slide....
for all instruments the spectrum changes as we ascend the scale(high tones - fewer partials)
Clarinet resonance curve(all tone holes closed)
The dots mark all multiples ofthe fundamentalfrequency even if higher modes are shifted, the partials arestill exact multiples since excitation is periodic
2
3
4 5 76
8
frequency (Hz)
Timbre depends on profile of instrument.
example: Oboe and Sax are both conicalreed 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,
A3b
B3b
Soprano Sax