No it add's very little resonance dampening to thicker steel, ok on thin sheet and better than nothing but only just.!!

Best way I've found is to use kiln dried sand, the stuff they sell for brushing in top block paving.
Seal ends, (expanding foam works here.!) with plates and put large hole at top & bottom for filling/emptying quite easy and makes big difference to vibrations and resonance coming from machine, plus it won't try walk off when shit it''s fan. . Lol (Those that have built and got it wrong will understand. . )