ABSTRACT
Not only is instrumental music highly evolved with respect to the instruments which it employs, but it is also characterized by the fact that each instrument is capable of producing notes with exact precision. The human vocal cords can also, if controlled by a highly trained nervous system, produce tones with precision. Under the ordinary conditions of vocalization, however, the vocal cords seldom take on the same degree of tension twice in succession. It requires a long period of arduous practice for a singer to strike a given pitch with precision. It is a wellknown fact that amateurs who try to sound particular notes only approximate the pitches at which they aim.
