Part 1. Considering building your own vocal studio.
The vocal booth is an integral part of the audio recording business. If you are planning to build a sound booth for yourself, consider first what is the desirable outcome: If you have to work with a low budget, think what you can live with. If you want a studio quality booth, this might take some dough.
The primary purpose of building a vocal booth is to create an acoustically engineered enclosure where the unwanted sounds, either external or internal, can be controlled.
External interference as well as internal echoing is eliminated. This can make crucial difference in your recording. Vocal booths also need to isolate the recording artist and contain the sound rather than risk getting contained by angry neighbors and doing so on a budget can be a real challenge.
Where to Build the Vocal Booth?
Now we are talking home, apartment, backyard, not a warehouse or professional studio space.
What to consider on a planning stage:
1) Will it disturb the neighbors? This actually should be the number one question to consider. If you build your vocal booth adjacent to your neighbors wall, and it is leaking sound the whole affair can turn very ugly very fast and police will be knocking at your door pretty often and pretty soon.
Conclusion: Try to stay away from partition walls. Try not to unnerve the neighbors.
Solution: Select an outer wall, below ground basement, garage. If you have no other options, then soundproof the wall properly. It will be a shame to have redo everything and it will get more expensive.
2) How large of a vocal booth do you need? Besides the obvious capacity, or what can you fit in that booth, there is a consideration of acoustics. Sound behaves differently in small rooms than in large rooms.
3) What is the shape of the room. Again , it is easier to build the square room, but this will create some problems down the line, like reverberation, standing waves etc.
4) How permanent of a structure do you need? Is it going to be the long term room or just a makeshift for a limited term? (like if you are renting for example.)
Once you figure this out you are ready to think of building materials.
The second question is Volume. How large do you want it to be? So the next issue will be:
How to Build the Vocal Booth?
What materials to use etc. Two components of building acoustically designed rooms or sound booths is Soundproofing and Acoustic Performance, which are not exactly the same. To make your vocal booth soundproof, ideally your sound booth should be a totally isolated sound enclosure, lifted off the floor, separated from the walls and ceilings. That is because sound waves/vibrations are transmitted through structural elements, concrete walls, etc. Therefore you need to separate the source of the sound. This will not help you with acoustic quality of the room, but will have everything to do with soundproofing. The size, shape of your structure, and acoustic treatment of the room (once the structure has been built) will have everything to do with the sound quality you can record.