the general acoustic tone when not plugged in is dampened and some sustain is lost but when plugged in and amplified you get a bit of a better/punchier tone and the feedback will be greatly reduced,my banjo player packs both resonators on his tenor and 5 string,randomly i think he has some car wash style sponges cut in half with some old t shirts in there! basically enough so there is even pressure applied between the skin and the resonator to dampen the resonance, you should notice instantly the lack of feedback on it.