Introduction to the concept of the sound
The first thing we perceive (consciously or even unconsciously) when we hear a voice singing, is always its sound. And it is a matter of taste and of other conscious or again unconscious factors, whether we're gonna like it or not. Regardless of all that, there are in fact some objective and undisputed elements, that constitute a beautiful voice.

Terminology such as tone of the voice, timbre, homogeneity of sound, range and volume are very well known and prove the great importance of the phrase " beautiful voice".
 
How can someone combine all the above elements, successfully?

Τo what extent can someone improve his/her vocal tone (timbre)?

A well known and acknowledged otolaryngologist, Alfred Tomatis has proven (in his book "The ear and the voice"), that each person produces the kind of sound, that his/her ear perceives. In other words, according to Tomatis, the ear is responsible for the kind of sound we produce with our voice, when we talk or when we sing.

Despite all those things, the quality of musical experience, stimuli and environment, where the body is free from any stressful factors, can boost the voice's most natural and free sound and help it produce its greatest possible range and volume.

And finally, become a powerful vocal instrument (making the best of all its range, volume and tone), which will allow the singer to acquire all the musical, expressive and improvisational skills, in order to be able to perform with musicality, self-confidence, freedom and pure joy.

After all...jazz singing means to be able to use your voice as a musical instrument.