Design and Acoustical Approach

To meet Intelligibility, Confidentiality or Concentration needs, Armstrong recommends a 2-Step Design Approach for specifying the correct ceiling for your acoustic comfort & health.

First, consider Passive acoustic solutions to absorb sound within a space, and block sound transmitting between spaces, dividers, or from outside the building.

Sound absorption - the part of incident sound that is not reflected by the tile. The typical expression for Sound absorption when ceiling systems are being tested is NRC (ASTM) or Alpha W (AS/ISO) and the measured value is between 0 to 1. The Sabin is the unit of total sound absorption provided by an object. This is the preferred metric for “space absorbers” such as discontinuous ceiling panels such as canopies or baffles installed within an architectural space.

Sound attenuation - the control of sound transmission between adjacent spaces with a common void above them The expression for Sound attenuation is CAC (ASTM) or Dncw (AS/ISO) and the measured value is typically in quoted in (dB).

Sound reduction - the control of sound generated in the plenum or coming from the floor above. The expression for Sound Reduction is Rw (AS/ISO) and the measured value is typically in quoted in (dB).

Please refer to our Technical Brochures for further information.



To complement your passive acoustics design and enhance Intelligibility, Concentration and Confidentiality, consider using active acoustics to:

  • Reinforce Speech, by increasing the signal-to-noise ratio for improved intelligibility
  • Mask sound to overcome “occupational factors”
  • Provide intelligible public announcements
  • Play music to create the appropriate atmosphere in a shop or waiting area