REsonance and sustain are different things. Resonance is the sympathetic vibration of the wood in relationship to the string's vibration. This actually saps the strenghth of the string's vibration.
Sustain is the maintenance of the strenghth of the strings vibration. This 'maintainence' of the vibration is extended when the difference in the density of the string and the density of whatever the string is attached to is increased. This is why a heaveier body sustains notes longer than a light body.
This reinforcement is the defining point of an acoustic....is the reinforcement/vibration of the top accurate, is the effect balanced across the frequency spectrum, and how strong is the sympathetic reaction. Once in a while you will find a bad acoustic top that creates harmonics that are 'sour'..unrelated to the picked note. Rare, but it happens. Some acoustic tops are uneven in their response....a G note might feedback with strong reaction and be much stronger than any other note on the fretboard. Some
Gibson 'jazz' guitars are 'G sensitive'...sometimes to the detriment of the sonics. This resonance is also what causes hollowbodies to feedback sooner at volume compared to solidbodies...moving air entering the 'box' and cusing the top to resonate to those frequencies in an 'excited' way.
A dense solidbody will have sharp attack, firmer tones, and longer sustain.
A less dense..lighter...solidbody will have a slower attack, less articulation, and less sustain. What one prefers is a personal thing....no good or bad..just different.
These differences in sustain, resonance, and articulation are what drove Les Paul to build the 'Log' that led to the Les Paul. This is also what led LEo Fenderto build the Tele,in addition to the ease of construction compared to a hollowbody guitar, I would think. Players were coming to understand what a solidbody guitar did. Paul Bigsby's guitar that predated the tele also is an example, and was probably more influential regarding Fender than the Log, which was probably known primarily to guitar players.
;D
