Hazrat Inayat Khan

"Very few in this world know to what extent phenomena can be produced by the power of the voice. If there is any real trace of miracle, of phenomena, of wonder, it is the voice."
The Voice
The voice is not only indicative of man'a character, but it is the expression of his spirit. The voice is not only audible, but also visible to those who can see it. The voice makes impressions on the etheral sphere, impressions which can be called audible; at the same time they are visible. Those scientists who have made experiements with sound and who have taken impressions of the sound on certain plates -- which impressions appear like forms -- will find one day that the impression of the voice is more living, more deep, and has a greater effect. Sound can be louder than the voice, but sound cannot be more living than the voice.
Knowing this the Hindus of ancient times said that singing is the first art, playing the second art, and dancing the third art which make music. The Hindus who have found that by these three different aspeacts of music one attains to spirituality much sooner than by any other way, have discovered that the shortest way to attain spiritual heights is by singing. Therefore the greatest prophets of the Hindus were singers: Narada and Tumbara. Narada inspired Valmiki who wrote the Ramayana and the Mahabharta, the great Hindue scriptures.
There are three principe kinds of voices: the jelal voice, the jemal voice, and the kemal voice. The jelal voice indicates power; the jemal voice indicates beauty; the kemal voice indicates wisdom.
If you take careful notice in everyday life, you will find that sometimes before a person has finished his sentence you have become annoyed. It is not because of what he has said, but it is his voice. And you will also notice -- perhaps not every day in you life, but sometimes -- that you once heard someone say something that has always remained with you: it gives always a beautiful feeling, it is always soothing, it is healing, it is uplifting, it is inspiring.
A doctor coming to see a patient may, by his voice, frighten the patient and make him more ill if his voice is not harmonious. And another doctor may, by his voice, treat the patient so that before the medicine is brought he is already feeling better. The doctor gives the medicine, but it is the voice with which he comes to the patient that counts.
In the history of the world have not men marched hundreds of miles with strength and vigor, not knowing what they were going to face, on hearing the voice of their commander: 'Quick march!'? It seemed that all fear, all anxiety were taken away, and all vigor and courage were given to them, as they were going to march. And again have you not heard of commanders who said: 'Fire!', and the soldiers turned back and fired at them? That is the voice too.
The voice, therefore, is a wine. It may be the best wine, and it may be the worst liquor. It may make a person ill, or it may uplift him..