Acoustics & Sound For Musicians - Online Book

The Theory Of Sound Which Constitutes The Physical Basis Of The Art Of Music.

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	IL § 29.] LIMITS OF MUSICAL SOUNDS.                59
	cause the Syren-sound to mount the scale until its pitch coincides with that of the note under examina­tion. During coincidence ascertain by the counting-apparatus the number of rotations which are being performed per second. This, multiplied by the number of holes in the disc, gives the number of vibrations per second required. It will be con­venient, for shortness' sake, to call the number of vibrations per second to which any note is due the vibration-number of the note in question. It is clear, from what has gone before, that any assigned degree of pitch can be permanently registered when once its vibration-number has been ascertained. 29. The Syren shows that below a certain rate of vibration no musical sounds are produced. The position of the absolute limit thus placed to the gravity of such sounds cannot be exactly defined, and probably varies somewhat for different ears. The lowest note on the largest modern organs has for its vibration-number, but it is a moot ques­tion whether the musical character of this note can be recognised. In any case we may regard the lower limit of musical sounds as situated in the immediate neigh­bourhood of this degree of pitch. For some distance above the limit the musical character continues very imperfect, and it is not until we reach about 40