Can I use a 4mm glass for a studio booth of 5 by 4 feet... How many mm glass is used normally for a vocal booth urgent answer please.

No idea. But you can check here for studio equipment https://www.nairaland.com/3799144/come-here-all-musical-studio

NnamdiN:
No idea. But you can check here for studio equipment https://www.nairaland.com/3799144/come-here-all-musical-studio

Studio or Voice booth?

BushDoctor123:
Studio or Voice booth?

voice booth

Princemanuel58:
voice booth

Why not use voice reflector, that is what is in vogue now except you intend building a voice booth that can take as many people at a time. if you have the cash go for the booth type. (my opinion anyway).

Princemanuel58:
Can I use a 4mm glass for a studio booth of 5 by 4 feet... How many mm glass is used normally for a vocal booth urgent answer please.

Better you use 12 mm double glazed with proper sealing (or even vacuumed space between the glass) but that would be a waste if you don't ensure the soundproofing of other likely leak spots i.e. get a soundproof door too.

If cash is an issue for this, take @BushDoctor123's advise and use an mic isolation shield and it can be DIYed by the way. Just use headphones and record...