There are things that you can do to help with sound isolation, but without bringing in some HVAC vents, you are always going to have the issues with heat and air circulation. I have heard of folks making DIY coolers with fans and ice chests, but if the room is truly sealed air-tight, you fan will burn out quickly, and you will eventually suffocate!

I am going on 2nd hand knowledge here, so excuse me for hi-jacking your thread without true experience, but from what I hear, most of those pre-made booths are not true isolation booths, but certainly cut down on the noise entering/escaping. The other benefit is that you can make the booth acoustically dead, which is *sometimes* beneficial for vocals (not sure if I totally agree personally with that statement...).

Sorry for the hijack, and hopefully you get some better answers from someone who has actually ordered one of these things.

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James
"Never interrupt your enemy when he is making a mistake" ~Napoleon Bonaparte~

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