# HANDBOOK OF ACOUSTICS - online book

### A complete view of Acoustical Science & its bearings on music, for musicians & music students.

 EXAMINATION PAPERS. 299 4.  (a) Describe the possible modes of vibration of a stretched string; {b) Draw diagrams showing the forms assumed by the string when the first two of these modes are superposed. Am.—(a) See p. 90 with fig. 46. {b) See No. 4 p. 5.    Describe the most accurate method known to you for determining the vibration frequency of a tuning-fork. Am.—Either the Graphic method, p. 36 and 37, or the Tonometric, pp. 150 and 151. 6.  (a) Explain the production of beats, (b) How many beats will be heard per second when two open organ pipes are sounding together, their frequencies being— (1)  200 and 203. (2)  200 and 403. Am.—(a) See pp. 144, 145, 146. (b) (1) 3 beats per second. (2) 403 — 400 = 3 beats per second. 7.    Give the formula for the rate at which sound travels through a gas, and point out how this rate will be affected by alterations in the temperature and pressure of the gas. Am.- V = ^1-41 Ł (1 + 2^) where P denote pressure of gas, D its density, and t denotes temperature. See also p. 20. ROYAL COLLEGE OF ORGANISTS. Questions 1.    What intervals do the following vibration fractions represent ? 15        8 5 16        5 3 Am.—See p. 51. 2.    Give an acoustical reason why one interval is more discordant than another. Am.—See Chapter XIV. 3.    What is the length of the C C pipe of the Twelfth stop P Am.—Take C = 540, CC = 67Ł, then length of C, pipe 1120 = 4 y 671 = 4 ft. 2 m. approximately. 4.    Why is the sound produced by a stopped Flue pipe an octave lower than that of an open pipe of the same length ? Am.—See pp. 60 and 61. 5.    Describe the constituent parts of (a) a Flue pipe, (b) a Reed Pipe. Am.—(a) See pp. 98 and 99 ; {b) pp. Ill and 112.