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Scan 23
Harvard Dictionary Of Music(1950), 1950
18 lines. Read by computer on 18 September 2026. No printed page number was found. See the scan on archive.org.
1ACOUSTICS
3is obtained as a differential tone of a 16-foot stop and a 10 2/3-foot stop. According to the acoustic phenomenon of the differential tones [see *Combination tones] the simultaneous sounding of C (produced by the 16-foot) and of G (produced by the 10 2/3-foot) produces the tone C₁ (32-foot). The acoustic bass is frequently used where the great expense of the large 32-foot pipes is prohibitive.
5Acoustics. The science which treats of sounds. From the standpoint of the musician the most important problems of acoustics are: (1) the nature of the musical sound; (2) *intervals; (3) *consonance and dissonance; (4) *resonance; (5) *architectural acoustics. Only the first problem will be treated here; for the others, see the respective entries.
7I. Vibration. The generation of sound is invariably bound up with the vibration of an elastic body, i.e., of a body which, when its equilibrium is disturbed, develops inner forces which try to restore the equilibrium. Such a process does not end at once, since the body upon returning to its initial position still has a certain amount of kinetic energy which causes it to go beyond this position so that a new contrary disturbance results. This leads to a repetition of the whole movement in the reverse direction and, in fact, to a succession of movements back and forth which would continue indefinitely were it not for friction, which causes them to diminish and finally to stop. A tongue of steel fastened at one end may serve as an example [Ex. 1].
9The movement A–B–A (or A–C–A or B–A–C) is called "single vibration" (half-vibration); the movement A–B–A–C–A (or B–A–C–A–B) is called "double vibration" or simply "vibration" or "cycle" (in modern writings usually the double vibration is used as the unit of measurement). The distance B–C is called "amplitude." The number of vibrations made in one second is called "frequency." Example 2 represents a vibration of 3 cycles.
11(In order to understand the relation of this graph to the vibration it is meant to represent, one may imagine the lowest point of the tongue, A, to be made luminous and then photographed. If for this purpose a single exposure of film is used, a horizontal dash (—) will appear. If,
13Ex. 1: Vibration of Elastic Body; O, fixed end; A, position of equilibrium; B, position of initial disturbance; C, reverse position. Ex. 2: Vibration of [address hidden]; a = amplitude; v = (double) vibration; s = single vibration. Ex. 3: Path of Vibrating Tongue. Ex. 4: Vibration of [address hidden] 5: Fading Sound. Ex. 6: Vibrating String; A, B, fastened ends of the string; C, point of plucking.
15however, a quickly moving film is used, this dash will appear drawn out into an oscillating curve [Ex. 3]).
17If the same tongue is plucked with different degrees of force, the ear will notice different intensities of sound, and the vibration curve will show different
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