The word "resonate" usually refers to the natural frequency of something. If you stand in a closed room with hard walls (like a small bathroom perhaps) and hum at a bunch of different pitches, you may find that some make the whole space seem alive with that pitch. This is one of the natural resonant frequencies of the space. If an instrument is made of "soft" material that does not "want" to vibrate naturally it is like hanging soft stuff in that hard room: the sound it makes will be muffled or dead. If the materials vibrate with the frequencies the instrument produces, it makes more sound - it sounds "alive." In a voice or a stereo speaker, this term typically refers to the production of a variety of pleasing tones, especially in the lower octaves. If a person has closed sinuses, the larger resonating volumes in the head are not contributing to the range of lower frequencies produced by the voice and the sound is thin or nasal. I am not sure how to compare this to other acoustic qualities... pitch is frequency, volume is how loud... richness might be the quality and quantity of harmonics... resonance typically makes one think of "full" sound.

Resonance is the process of changing (alternately) between two types of energy states. Many objects in nature have this property. Many man -made devices have this property (radio tuner circuit). The energy in a swing set transfers between static(height) and potential (velocity)energy. The occurance of resonance is usually only seen when the process goes on for a relative long time. However, resonance occurs in many systems (things and stuff) . We dont see it because energy is lost as heat or we cannot hear see feel or taste it. No one has a resonate breakfast cereal yet? Believe it