A theatre is isolated from the foyer, the plant and the neighbours, then absorbed inside.

The auditorium

The auditorium shell — double walls or heavy concrete, a lid independent of the building roof, and usually a paired acoustic door — is what keeps the street and the foyer out of the show. Inside that shell comes absorption: clouds, baffles or a wall lining, to set the reverberation time. Speech wants a shorter tail than music. An internal RT60 is not evidence that the neighbour cannot hear.

• Auditorium doors: a doorset, not a leaf. The frame, the threshold and the drop seal are the leak.
• The control room looks through glass. Observation glass is specified as an isolating element, not as décor.
• The orchestra pit and under-auditorium corridors are flanking paths if they connect to a quieter volume.

Stage and backstage

The fly tower is tall and often light, so rain and wind arrive as impact noise unless the roof is separated. Backstage and dressing rooms need insulation from the auditorium so the house does not hear talk behind the curtain, and insulation from each other. Winches and motors put vibration into the structure; the resilient mount and the break to the frame are drawn with the structural engineer, not after installation.

Plant and quiet

An NR target inside the auditorium dies if one duct runs from the fan room to the house without a silencer. The silencer, the duct velocity and the lined bends are part of the insulation as much as the wall is. A generator or chiller a metre from the house is not treated by an absorbing ceiling in the house.