The universal rule — treat primary reflection points first
The primary reflection points are the walls that reflect sound directly from the source (speaker or speaker) to the listening position. In a mixing room, this is the two side walls at the reflection points of the front speakers. In a home theatre, same. In a boardroom, this is where the speakers on the video call microphone are pointing.
Test with the mirror trick: sit in the listening position, have someone slide a mirror along the wall at seated head height. Anywhere in the mirror you can see the sound source is a primary reflection point. Panel there.
By room type — home theatre
Side walls at primary reflection points: absorber panels (50 mm foam or fabric-wrap).
Ceiling above the seating position: cloud panel with air gap.
Front wall (behind speakers): heavy absorption or gripper-fabric infill.
Rear wall: diffusion (broken-up surface, not absorption) to preserve envelopment.
Corners: bass traps floor-to-ceiling.
By room type — office / boardroom
Ceiling: PET clouds or baffles above the meeting table. Biggest single win.
Rear wall (opposite the display): absorber panels.
Side walls at head height: absorber panels behind seating.
Corners and floor: usually untreated in offices; carpet does the floor work.
By room type — restaurant / hospitality
Ceiling: PET clouds or baffles above the dining area. 40–50% ceiling coverage typical.
Walls behind banquette seating: absorber panels (helps guests hear their table-mates).
Feature wall as design element: gripper-fabric wall or wood-wool board with printed pattern.
Floor: acoustic carpet or heavy rug in dining zone (helps chair-drag and footfall noise).
The corners rule — never skip them
For any room where bass response matters (home theatre, studio, cinema), corner bass traps are non-negotiable. Skip them and no amount of wall treatment saves your low-end.
For offices and restaurants, corner treatment matters less — but if you have room for it, corner treatment is always a modest bonus.