How Meeting Room Finishes Affect Acoustics

Written by: Alex Frew

In general there are a couple of principles that can make for a "good" sounding room or space, dependent on what a person is listening to. One general set of classifications can be:

  • Contemporary Music – the listening experience can be enhanced by echo or reverberation to some degree. However, speakers often need to have good bass response and the reverberation (echo) should be consistent at all frequencies.
  • Classical Music - long reverberation or echo can improve the perceived sound quality to the extent that speaker systems are often not used, and the natural echo or reverberation of a hall or space is preferred. Think of a Church or Classical Recital Hall.
  • Speech - bass response is not important, but high frequencies are critical. High frequencies help us determine critical vowel and consonant sounds. Limiting reverberation (echo) is also key to a good speech sound system.

Of course these are general rules and there are rarely spaces designed these days for one purpose in particular. So there always needs to be some balance and consideration to all the uses of a room or space.

There is an Australian Standard for business meeting rooms, however, which sets an RT60 range of 0.5-0.7s for standard meeting rooms, and slightly less for rooms with Video Conferencing functionality.

There are no general rules to determine if a room will meet these criteria or not. Typically, calculating the reverberation time (echo) requires many variables including room volume, internal surface area, and the absorption efficiency (coefficient) of those surfaces.

However, the simplest reference when planning for these types of rooms is that a typical residential lounge room has similar reverberation time to a standard meeting room. I’ve often found that trying to design the meeting room finishes with an even balance (surface area) of “hard” or “soft” finishes gets the reverberation time pretty close to achieving the standard.

Soft finishes are typically things like:

  • Ceiling tiles
  • Pin board panels
  • Specialist perforated plasterboard or timber panels
  • Carpets and rugs, softer and thick if possible
  • Curtains

Hard finishes are typically things like:

  • Glass & mirrors
  • Concrete, brick, blockwork, or rendered masonry
  • Whiteboard or Metal
  • Polished or Laminated Timber

It is possible to achieve these design standards by using a balance of finishes across the surface areas of a room. If required specialist acoustic panels can be used to offset large areas of hard surfaces. However this solution is likely to be more expensive and be less predictable than evenly distributed soft finishes or acoustic absorption.

On the other hand, Video conferencing spaces or similar highly important communication spaces are more critical in terms of voice listening and intelligibility. Specialist acoustic treatment is often required to achieve the quality and frequency control that is needed for lots of voice communication. These rooms are more likely to require careful acoustic, speaker, and microphone planning and placement to achieve good results. 

These more critical types of spaces normally require the input and advice of an Audio Visual or Acoustic engineer, however the general outline above is still a good starting point and will certainly get you close to design standards.

 

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