HANDBOOK OF ACOUSTICS - online book

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

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70
HAND-BOOK OF ACOUSTICS.
direct the attention to the G in the Treble staff an octave and a fifth above it. This is generally more easily recognised than the preceding, and is usually equally loud. When this has been clearly heard, strike the same note as before, and listen for the C1 in the Treble staff, two octaves above it. More difficulty will perhaps be experienced in detecting this, but by the aid of properly tuned resonators, it will be heard sounding with considerable intensity. The next two sounds are better perceived as the tone is dying away; they are the E1, two octaves and a major third above the sound struck, and the G1 two octaves and a fifth above.
The student should vary this experiment by taking other notes, and listening to their constituent elements. These latter will always be found occurring in the above order : thus if the D in the Bass clef be struck the following sounds may be heard:—
No sound intermediate in pitch between any of these will be detected. Further, these sounds are not aural illusions, but have a real objective existence, for they are capable of exciting corre­sponding sounds in other strings, by resonance. Thus, having softly pressed down any key, say (d), without sounding it, so as to raise the damper from the wires, strike sharply the octave below (d|) and after a second or two, raise the finger from this latter, so as to damp its wires; the note (d) will be plainly heard, the corresponding wires having been set in vibration by resonance. This experiment will be found successful with all the constituent parts given above. For example, press down the on the top line of the Treble
staff, but without sounding it, and strike sharply the two
octaves and a major third below. Raise the finger from the latter after a second or two, and the wires of the former will be heard giving forth the
All the constituent elements of a compound tone given above, are very prominent on an American Organ, and still more so on the Harmonium. They will be found to be in exactly the same order,