The effect of a sound-absorbing ceiling is not determined by an NRC number. Slab thickness, perforation rate, back cavity depth, fill material, keel system and mounting method all combine to affect reverberation, echo and speech intelligibility.

1. The difference between NRC and sound insulation

NRC reflects the material's ability to absorb sound, and Rw or STC reflects the partition's ability to prevent sound transmission. The conference room needs to control the reverberation, and the computer room and equipment room also need to pay attention to the sound insulation, and the indicators cannot be mixed.

2. Determine goals by space

Offices, schools, hospitals and stadiums have different sound absorption needs. Open office areas focus on reducing human voice interference, gymnasiums focus on controlling echo and reverberation, and hospitals also focus on cleanliness and moisture-proofing.

3. Structural factors

• Plate thickness and bulk density affect low frequency absorption.
• Perforation rate and pore size affect mid- and high-frequency absorption.
• The deeper the back cavity, the better the low frequency absorption is usually.
• Backed with acoustic cotton and non-woven fabric to improve performance and control fiber shedding.

4. Installation control

The panels should be closely assembled or seams should be left in accordance with the system requirements. Lamps, air vents and inspection openings should not damage the continuous sound-absorbing surface. Large-area suspended ceilings should be controlled in zones to avoid uneven joints and local subsidence.

5. Acceptance Checklist

• Check NRC report for thickness, construction and installation conditions.
• Check whether the sample is consistent with the batch supply.
• Conduct on-site acoustic testing of critical spaces.
• Keep concealed photos and certificates of material qualification.

Sound-absorbing ceilings should start from the acoustic goals, rather than just looking at material parameters. Only by unifying construction, installation and acceptance can we achieve stable and reproducible acoustic effects.