<p>I’m an audiologist and I live with two drummers, my husband and my 15 yo son. Our drums are in the basement so we are very lucky. My husband used to put a blanket in the bottom of his bass drum when he lived at his mother’s house - that’s his tip <g>. However, being an audiologist, when my younger son started to play the drums I insisted that he have a second set of drums - Roland’s electric drums (yeah, I know, they are not cool) -because ear protectors do not necessarily reduce the sound level of the drums below the potential for damage. Yes, Roland’s are expensive - I believe we spent $3000. And, yes, they don’t sound or feel exactly the same - but, they have been very useful for both of them although they prefer the “real drums” for playing out. </g></p>
<p>I recently took a noise course geared to industrial noise and imporving classroom acoustics. I have to agree with the fireman - anything put up to absorb sound has to be rated for fire safety. Plus, it should be rated for it’s sound absorption coefficient - no point putting up something with a low absorption coefficient. If you could construct, it seems that a second wall with air between the two would be a great way to reduce the transmission of sound to the outside. But, you might want to consider some wall boards that go up like paneling or sheetrock - they are made by acoustics companies. I recently looked at some that felt like corduroy. It would be like paneling one wall.</p>
<p>Where are the drums located - you could start by moving them as far away from the wall facing your neighbor as possible and locating the sound out in the opposite direction. Sound decreases fairly quickly by distance, some frequencies more than others, so consider relocation of the instruments. What is in the room - are there a lot of reflective surfaces? Is there carpeting? Carpeting can make a big difference. The more you cover the surface of the offending wall, the greater you will decrease the reverberation and sound transfer. There are many acoustical products outthere, some of which don’t look so bad! I recently looked at wall panels that had a corduroy appearance and very high sound absorption coefficient. There is a formula for calculating the reduction of reverberation or the amount of absorption by looking at the spaces (volume) that have been covered and by what, presuming it has been measured. Basically, covering your largest areas gives you the greatest effect - carpeting on floor and large quilts or full acoustic panels on the walls</p>
<p>That said, people tolerate impulse noise far less well than they tolerate something they can hum. Drums fall into this category. Even if you decrease the transfer of energy by 50% your neighbor may still complain of the offending quality. In this case, you may actually some things on your side. Both the EPA and the WHO (World Health Org) offer standards for sound level, over specific parts of the day. As meaured from yoru neighbor’s propertly line, for example, if the sound falls betow 55dBA during the day or beow 45dBA, it may not be a problem (these are example figures - don’t have my books here). You might want to check your town regulations for noise - most are quite vague. Although you don’t want to anger your neighbor, there are probably times of the day when the noise falls within limits.</p>