Reverberation Time Measurements

Sound Level Meter for Room Acoustics | Model 831-RT

831 Sound Level Meter

Whether for performance venues, architectural measurements or work-place acoustics, reverberation time is a key parameter for characterizing a room. A long reverberation time can make speech less intelligible and music can become garbled. Too short a reverberation time can muffle speech and make a room sound "thin". The 831-RT firmware option adds reverberation measurement and calculation functionality to the Model 831 sound level meter.

831-RT firmware was designed with simplicity in mind yet complies with the latest ISO 3382-2 and ASTM E2235-04 measurement standards. It supports both the Integrated Impulse Response and Interrupted Noise excitation methods and includes an automated trigger to easily control the measurement. The on-board signal generator provides a pink or white noise source for optional amplifiers and omni-directional or façade speakers via the AC/DC output connector on the Model 831.

The user can display an individual RT spectrum and discard those with erroneous data. The spectra from multiple positions are ensemble averaged to display an overall RT60 calculation.

A full battery of quality indicators supports the validation of measurements. Additionally, grading of the measurement according to ISO 3382-2 indicates whether sufficient positions (microphone-source combinations) have been acquired to obtain the expected grade: survey, engineering or precision.


  • Automatic RT-60 computation
  • Integrated impulse response and Interrupt noise methods
  • ISO 3382-2 and ASTM E2235 compliant
  • Onboard quality indicators
  • Include/Exclude measurement
  • Built-in pink and white noise source
  • Automatic triggering
  • 1/1 and 1/3 octave filters supported
  • T20 & T30 reported
  • DNA support for full building acoustics suite


  • Architectural acoustics
  • Room Acoustics
  • Materials testing
  • Reverberation time