THE VOCAL MECHANISM65

Amplitude is the physical term for the size of the sound vibrations, measured objectively. Loudness is the psychological term for the strength of the tones heard. A subjective judgment. Timbre is the physical term describing the vibration form of the sound waves, in terms of the relative strength of the partials present.

Quality is the psychological term for that characteristic of a tone which distinguishes it from another tone having the same pitch, loudness and duration. The physical phenomena - frequency, amplitude, and vibration form -can be measured with reasonable accuracy with modern-day equipment. The psychological phenomena are difficult to measure accurately since they are sensations in the brain and vary in complex ways.

Pitch66

Pitch is the audible quality of a musical tone which reveals its position in the musical scale. In singing it is determined by the double vibrations per second of the vocal cords - the larger the number the higher the pitch, the smaller the number the lower the pitch. Generally speaking, the vocal cords are more like wedges8,7and can vib¬rate in three dimensions - depth, width, and length. It is through their proper adjustments into at least three registers, that the full pitch range and good intonation of the singing voice can be established.

The pattern of the register adjustments68

a low voice of an octave, a middle voice of a fifth, and a high voice of a fourth, with an additional third or more for the coloratura register, would seem to follow a natural law of vocal production in relation to pitch. Although the extent of the first register, beginning with the average pitch of the normal speaking voice, is quite de¬finite , the extent of the second register is a variable depending on the vowel sound that is sung. The ah vowel sound fits the pattern of a fifth, since it is the last vowel sound that needs to change to the high register.

The register theory would seem to bear some relationship to the over¬tone theory, at least within the overall range of the singing voice from low bass to coloratura soprano. According to the overtone theory, all musical tones are complex. They are made up of a fundamental, which is the tone that has the lowest frequency, and tones above the fundamental which are called overtones.

The fundamental is the first part of the complex tone and is called the first partial; the second part is called the second partial or the first overtone; the third is called the third partial and the second overtone, and so on. These partial tones make up what is called a harmonic series which follows a definite pattern above the fundamental, of an octave, a fifth, a fourth, a third, and on upward above the range of the human voice. The result is a complex combination of many partials which are difficult to pick out but are heard in the overall effect.

Loudness 69
Basically, loudness in singing is dependent upon the amplitude of the sound vibrations, which are dependent upon the pressure flow of the breath and the ability of the vocal cords to control this pressure flow.