If that which is perceived as voice is in a purely physical sense nothing but the movement of air set in motion because of the activity of muscles, then it is the tensors of the vocal folds, the cricothyroid and arytenoid muscle systems which maintain vocal fold vibratility, that form the very core of the vocal mechanism. Consequently, whatever inhibition of movement takes place as the vocal folds are drawn into tension ensures that all other areas of function will likewise be inhibited. Whether it be a question of range extension, precise intonation, an ability to run scales smoothly and rapidly, sustaining a pure legato line, achieving articulatory freedom, purity of the vowel, an even, expressive and unobtrusive vibrato, or efforts made to enhance resonance characteristics, all of these desirable functions rely for their freedom on the precision with which the tensor mechanisms of the vocal folds interact. Therefore, the attainment, regulation and control over these technical and artistic objectives depends upon an understanding of registrational mechanics.