The screen wall — where fibreglass wins
Behind the acoustically-transparent screen sits the front speaker array. That wall needs the deepest absorption in the room — NRC 0.95+ at 50 mm thickness. Fibreglass boards at 64 kg/m³ or 96 kg/m³ density are the standard specification.
Boards install inside gripper-fabric frames with a 10 mm air gap between the board and the fabric. The gap improves low-frequency absorption; the fabric absorbs any direct reflections that would otherwise interfere with the speaker system.
Inter-hall isolation — STC 60+
Multiplex cinemas need STC 60+ between adjacent halls. Standard construction: staggered-stud walls with 5 MM MLV inside, poly wadding in the cavity, double drywall on each side.
The trick: seal every penetration. HVAC ducts through inter-hall walls are the most common failure point. Duct silencers on both sides and MLV wrap around the duct penetration.
Auditorium treatment — controlled but not dead
Cinema RT60 target: 0.3–0.4 s at 500 Hz. Long enough for the audio track to sound natural; short enough for dialog to be intelligible.
Side walls: fabric-wrap gripper panels with 50 mm poly wadding or 25 mm rockwool infill. 60% coverage typical.
Rear wall: diffusion (broken-up surface, not absorption). Preserves envelopment for surround effects.
Ceiling: baffle system or fabric-wrap panels with poly wadding infill.
Lobby, corridor, and stairwell isolation
Lobby noise is public — chatter, phones, and food-service noise. Absorbers on ceiling and walls to prevent bleed to auditoriums during between-show periods.
Corridor noise: PET or fabric-wrap panels on walls plus acoustic carpet on the floor. Prevents guest-perceived noise from other halls.
Stairwell isolation: often overlooked. Stairwells transmit sound between floors like giant vertical ducts. MLV inside stairwell walls plus door seals on each floor.
HVAC — the invisible acoustic challenge
Cinema HVAC has to deliver comfort without becoming audible. Duct silencers on both intake and exhaust. Fan-coil units isolated on rubber mounts. Air velocity kept low enough that no whistle occurs at supply grilles.
This is often the single most expensive part of a cinema build — but skip it and the entire acoustic investment underperforms.