The three problems a booth solves
External noise: traffic, HVAC, and household sound bleeding into the mic. Solved with mass and sealing.
Reflections: mid and high frequencies bouncing off the four close walls and colouring the vocal. Solved with heavy absorption on every surface.
Modal problems: standing waves at frequencies determined by room dimensions. Solved by keeping the booth small enough that mode frequencies fall above the fundamental voice range.
Construction — the isolation shell
Standard construction: 100 mm timber stud frame with MLV bonded to the exterior face of the drywall, poly wadding in the cavity, standard drywall on the interior. Ceiling built same way; door is the weakest point — use a solid-core door with acoustic seals on all four edges.
Add HVAC — a small fan-forced vent with duct silencers on both intake and exhaust. Skip HVAC and you'll suffocate; add unsilenced HVAC and it'll be the noise floor of every recording.
This construction delivers STC 45–50, which drops external noise to broadcast-friendly levels for most residential settings.
Treatment — kill everything above 300 Hz
Standard booth treatment: 50 mm wedge foam on all four walls and ceiling. Cover 80% of the wall area; leave 20% for the door and any window.
Wedge foam absorbs deep into the mids; pyramid foam is second choice. Fabric-wrapped rockwool panels are the premium option and last longer than foam.
The floor stays hard (wood or vinyl over concrete) — you need something acoustically bright for standing/sitting comfort during long sessions.
Lighting, ventilation, and monitoring
LED lighting — never fluorescent. Fluorescent lights buzz at frequencies that show up on recordings.
Silent HVAC — as above. A room without ventilation isn't a recording space, it's a suffocation chamber.
Talkback and headphone monitoring — hardwired, not wireless. Wireless introduces latency that kills singer performance.