We have just learned that the pitch of sound depends on the rapidity of the vibrations. This depends on the length of cords and their tightness for the shorter and tighter a string is, the higher is the note which its vibration produces. The vocal cords of women are about one-third shorter than those of men, hence the higher pitch of the notes they produce. In children the vocal cords are shorter than in adults. The cords of tenor singers are also shorter than those of basses and baritones. The muscles within the larynx, of course, play a very important part in altering the tension of the vocal cords.