Room Acoustic Measurements

Room Acoustics

This page provides an overview on the subject of Room Acoustics. We cover the terminology and list the key measurements required to determine the acoustic properties of a room. We also provide links to how each actual measurement is done.

Room Acoustics is distinguishable from Building Acoustics, which essentially deals with the insulation of noise from other rooms or the outside world.

Recommended Solution for Room Acoustics

What do Room Acoustic experts measure?

Room Acoustics is a broad term that describes the acoustic properties of closed spaces. Measuring and controlling this behavior of waves is particularly useful in rooms where the quality of announcement messages and/or music is important, such as in conference halls, classrooms, concert halls, recording studios, airports, and train stations.

There are three main measurements that assist Room Acoustic experts in characterizing the acoustic properties of a room.
(The links will take you to the information about how these measurements are actually done.)

Reverberation RT60 a measure of the time required for reflecting sound to "fade away" in an enclosed area after the source of the sound has stopped
Speech Intelligibility STI a measure of the quality of the transmission of speech
Background noise Noise Curves an indicator of the potentially disturbing influence of ambient noise


Why is it necessary to measure?

Rooms with too many or too few reflective surfaces, or too much or too little background noise can affect people’s moods and psyche.

Think of how cold and loud a conversation sounds in a hospital with tiled, reflective surfaces compared to how warm and soft a conversation sounds in a cinema with cushioned seats and walls (of course the purpose of the location has a significant effect on your mood too).

Think of how your mood changes in your office when a heavy construction machine starts up nearby. It is difficult to relax in such a space. Such unnatural-sounding rooms may also make speech difficult to understand, thereby affecting our ability and desire to communicate.

Every room needs to have the background noise under control to make the room fit-for-purpose.

The room should also respond acoustically with an appropriate amount of reverberation. For example, for good speech intelligibility in a classroom, the reverberation time should be around 1 second or less. A classical music concert hall, on the other hand, needs reverberation times of 2-3 seconds to ensure a rich and warm listening experience.


Which measurement instrument do you need?

In order to carry out room acoustic measurements, you need an acoustic analyzer that can measure RT60, STI, and Noise Curves in compliance with your national and international standards.

With the handheld XL2 Acoustic Analyzer you get all three measurement functions combined in one device. Thanks to the simple operation, you can comfortably switch among the three measurement functions, and produce professional reports. 

5 reasons why the XL2 is the right choice for you

XL2 Acoustic Analyzer for Room Acoustics Measurements
XL2 Acoustic Analyzer for Room Acoustics Measurements

  • the XL2 is easy to use.
  • the XL2 automatically detects the sensitivity of the microphone for indisputable accuracy.
  • all measurement results are stored on the removable SD card as TXT files, which can be further processed externally with a PC or MAC.
  • besides the three Room Acoustic measurements, the XL2 has many other expandable measurement functions. So, if you have other acoustic or audio measurement tasks, it's likely that the XL2 can help you.
  • Together with the Type Approval Option, the XL2 is an approved Sound Level Meter.

DS3 Dodecahedron Speaker Set

The Dodecahedron Speaker Set, comprising of the Dodecahedron Loudspeaker and the Power Amplifier, is the measuring equipment designed for professionals for use in their daily measuring tasks in room acoustics. Optimized design, combined with unique precision, low weight and flexible operation establish this equipment as a reference in the marketplace.

  • Acoustically flat frequency response 
  • Maximum sound power level 120.5 dB 
  • Wireless remote control

DS3 Dodecahedron Speaker Set Product Data

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International Standards

Room Acoustics measurements are defined by international and national standards.

  • STI is measured in accordance with IEC 60268-16: 2011 standard (editions 2, 3, 4), while the procedure for determining privacy and distraction distance in open-plan offices corresponds to the ISO3382-3 standard.
  • RT60 measurement is defined in the ISO 3382-1 standard for performance spaces and the ISO 3382-2 standard for ordinary rooms, as well as the ASTM E2235 standard.
  • Noise Curves are measured in accordance with the ISO 1996: 1971, ANSI S12.2-1995, ANSI S12.2-2008, and ASA 1971 standards.

Where to next?

Here you can dig deeper into each of the actual measurements:

News Articles about Room & Building Acoustics

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