It is more plain and easier to understand that the voice has a certain psychological value, that one voice differs from another, and that every voice expresses its psychological value and has its psychological power. Often one feels the personality of the one who is talking at a distance over the telephone. A sensitive person can feel the effect of the voice alone, without seeing the speaker. Many do not depend so much upon the words as upon the voice that is speaking the words. This shows that one's psychological development is expressed in speaking, and more especially in singing.