III | Physical View Formation of Sounds by the Vocal Organ
For the artistic culture of the singing voice the knowledge of the physiological processes during the formation of tones does not suffice. This knowledge brings us acquainted only with the instrument, the artistic treatment of which is to be learned. Having, therefore, in the preceding pages stated the most important points in the formation of tones, physiologically considered, we are now to consider more nearly the physical laws relating to the same, especially as the physical view of the subject, through the latest investigations and discoveries of Prof. Helmholtz, in Heidelberg, has so much importance for music in general. In order, however, to present a clear view of this branch of our subject, in so far as the recent advances of science can be practically applied to the improvement of the art of singing, we must recur to those natural laws which are doubtless well known to most of our readers.
In order to bring the external world to our consciousness, we are provided with various organs of sense; and as the eye is sensible to the light, the ear is sensible to sound, which comes to our consciousness either as noise (Geräusch) or as tone (Klang). The whistling of the wind, the plashing of water, the rattling of a wagon are noises, but musical instruments give us tones. When, however, many untuned instruments sound together, or when all the keys within an octave are struck on the same time, then it is a noise that we hear. Tones are therefore more simple and regular than noises. The ear perceives both by means of the agitation of the air that surrounds us. In the case of noise the agitation of the air is an irregularly changing motion. In musical sounds, on the other hand, there is a movement of the air in a continuously regular manner, which must be caused by a similar movement in the body which gives the sound. These so-called periodical movements of the sound in the body, rising, falling and repeated at equal intervals, are called vibrations. The length of the interval elapsing between one movement and the next succeeding repetition of the same movement is called the duration of vibration (Schwingungsdauer), or period of motion.