Resonance, vibrato, and onset/sustain/release are related; each affects the other. This page shows two examples of how these are related: phonation of the words "hope" and "life" while practicing the song "The Circle of Life" from Disney's The Lion King.
One characterization of Resonance is how full, or how many overtones, are present when singing a note. In the pics below, the main overtones of a note are shown in yellow. This is visually seen in spectrographs as shown below.
Harmonics or overtones?
1. Harmonics are frequencies that are integer multiples of the fundamental frequency. For example, if the fundamental frequency is 100 Hz, the harmonics would include frequencies at 200 Hz (2nd harmonic), 300 Hz (3rd harmonic), and so on.
2. Overtones are a broader term that encompasses both harmonics and additional frequencies that may not be integer multiples of the fundamental. Some use these terms loosely and interchangeably.
In voice resonance, overtones refer to all the frequencies present above the fundamental, including both harmonics and other non-integer multiple frequencies.
Onset/sustain/release refers to how a word is started, sustained, and then finished. This is best seen in audio editing software, i.e., Audition.
Vibrato is a type of vocal effect where a note changes pitch subtly and quickly. There are two body locations where vibrato initiates (types) and a stylistic vibrato:
1. Core or diaphragm vibrato (gut area - first and second chakras) - initiates onset from the core. This is subtle and sounds most natural, mostly used for jazz, Disney's songs, and pop.
2. Throat vibrato (mostly used in rock and some pop) - initiates onset from the throat (pharynx).
Stylistic Musical-theater vibrato - half step down then return, repeat at a fast pace.
The musical-theater vibrato is stylistic and can be applied on top of either core and throat vibrato.
The key to vibrato production is relaxation of the area producing it. For core vibrato, everything above the core area is relaxed, not tight.
From a sound physics point of view, vibrato allows more anchoring. Power (sound volume) is spread over frequencies above and below the main note, allowing a more 'round' and fuller sound (see discussion of the word "Hope" in "The Circle of Life" below).
