HANDBOOK OF ACOUSTICS - online book

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276                     HAND-BOOK OF ACOUSTICS.
Longitudinal wave.
N = — (See p. 119.)
3700
= ----- = 37
100
(b) Transverse vibrations ; harmonics.
{e) Exciting agent: the wind which cannot excite longitudinal vibrations.
(d)  The beating is due to high partials.
5. («) What is meant by a combination tone ?
(b) How may one be produced so as to be directly audible P
(e)  Give a general explanation of the production of such a tone. Am. (a) See p. 135.
(*) See p. 131.
(e) See pp. 133 and 134.
Afternoon. 2 to 5.
1 (a) What effect will be produced by a rise in temperature on the pitch of the notes given out (1) by stretched strings, (2) by organ pipes ? (b) An organ pipe sounds at 0° O. a note with 256 vibrations per second. What will be the frequency of the note given out by the same pipe at 20° C. ?
Am. (a) 1. See p. 90. 2. See p. 100.
/ 1 + 20 (b) Frequency = 256 V            — (See p. 100.)
Zi to
= 265-2
2.    The velocity of sound through air at 0° C. is 1,100 ft. per second. What will be the velocity of sound through hydrogen at the same temperature ? 1 litre of hydrogen weighs "0896 grms.: 1 litre of air, 1293 grm. at 0Q C. and atmospheric pressure.)
Am.—Velocity in hydrogen
/l 293 = 1100 X V -— (See p. 20.) •0896           r
= 4,179 ft. per second.
3.  (a) Explain, by the aid of carefully drawn diagrams, how beats are produced, and
(b) Show how to find the number of beats per second when the frequencies of the component beats are given. Am.—See p. 145. (*) See p. 153.
4.  (a) Define the terms node and loop.