Re: Drums without a resonant head (open drums?)
For sound insulation, you can also try (if you can find it) large "egg crate" type material that is used in chicken houses. The poultry supply houses are plentiful here in the South, but can be difficult to find in many places (particularly urban areas). Good luck with the sound proofing, but definitely get a de-humidifier ir you are in a humid area. Plus the fan is a good idea.