Practice booth for garage

[HughBrock]

I am in Vancouver Canada, and wish to build a practice booth in my garage for playing Irish flute and uilleann (Irish) bagpipes. The Irish flute maxes out around 85 dB (C weighted slow), and the pipes at 95 dB. The range of the pipes is from 150 Hz to 1 kHz, , but the octave from ~150-300 is about 85 dB max. So I don't have to worry about low frequency noise. I am in a quiet suburban neighbourhood, where the loud noises are the usual garden equipment (mowers, blowers, trimmers). Given that loudest sound wins, I am unlikely to be bothered by external noise while inside the booth....

My goal is to reduce the audibility so that I can rehearse many hours a day without disturbing the household. If my wife wears industrial hearing protection rated at 23 dB, she says it is audible but acceptable from inside if I play in the garage. I am hoping for 40 dB or more reduction (the neighbours would likely appreciate 50 dB...). I realize the booth is too small to record, so I will be aiming for minimal acoustic treatment in order to conserve maximum interior space.

I have limited space (4'3"x5'6") but can borrow the external wall of the attached garage (see attachment). The garage has a cement floor, a 10 foot ceiling, but the garage door opener limits the heath of the boot to 8', but I could put the silencer boxes up there.

Given the small size of the booth I can use the best materials and still likely come in at about 20% of buying a commercial booth. At this same time, I understand that the system is only as good as its weakest link, and there is no point overbuilding.

From the Viracon website which publishes an exhaustive range of possibilities for double pane windows with laminated glass, it seems that it is possible to get to STC of 50 in test situations with 4" spacing between two lites of unequal thickness. Given the size of the booth,I think it will be claustorphobia-inducing, so I would like a window. Thoughts about window shape and size?

I don't have a good idea of how much TL I can achieve with a door. If the doors were not very wide (24") I could build back to back solid doors. I could also build a door with same construction as the wall, although I don't see that recommended here very often. Or I could build a single thick and heavy door. Thoughts about optimal solution and potential STC?

Similarly, I don't know how to gauge the relative merits of drop down seals vs cammed hinges, door gaskets vs (or in addition to) weather stripped, perhaps using a door with stepped panels so that each edge sees at least two stops and weather stripping.

Given the space premium, I am willing to use commercial sound damping drywall. I realize it is expensive, but it's not as expensive as annoying my wife by having the booth too big....Otherwise I was thinking of 2 layers of 5/8" wall board and green glue. If there was a benefit, would be happy to use layers of different thickness, or have cement board, MDF layers, but I don't see being able to build a window and door that can match. Thoughts?

In trying to design this, the first problem is using the exterior wall. As shown in the pdf, there is an 18" high cement wall that is about 2" proud to the drywall on the inside. The diagram on the left shows one possibility, namely adding pdf and green glue to add mass, and a uniform surface. On the right is another idea , namely leaving the exterior wall as is, and adding an inside out layer so that there is at least some interior treatment. Thoughts or alternative suggestions?

I am very glad I came across this forum! Not only will it save me a lot of money from not buying a commercial booth, it gives me an interesting project to do. I am amazed and impressed by the wealth of expertise here, and the quality of the contributions. I would have made SO many mistakes......

Thanks in advance,
Hugh

You can't make things idiot proof, only idiot resistant....