Announcements:

1
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 730 St. Frances House Helen (viola)
Saturday 230 St Frances House Gayle (piano)
winner Beethoven Piano Competition
D-minor Sonata Op. 31 2 330 Sun Morphy Greg,
Daniel (Tuba) Tuba and Euphonium Ensemble 2 pm
Sat. Mills Concert Band 2
pm Sunday Mills Friday 730 Music Hall acapella
concert Elise (Bassoon) Saturday May 4 at 1 pm
St. Frances House Andrea? Others?
2
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

3
oboe, bassoon, clarinet
who can bring bassoon?
4
profiles of reed instruments (vert scale enlarged
3-times)
5
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
6
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)

7
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)
8
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
• -gt lower freq cutoff
• large tone holes of Sax
• loud! strong low partials
• Oboe has
• small opening angle, small bell
• -gt high freq cutoff
• small tone holes
• soft,

B3b
A3b
Soprano Sax
9
Saxophone instrument designed (rather than
evolution)
10
Construction of a violin
11
cross section of violin
12
see papers by Carleen Hutchins
is there a detectable difference between Strads
and other violins?
13
Strads
other old Italian masters
Tuning of the lowest resonances of different
violins
14
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