The objective of the acoustic system for the conference room is to control the audio quality to match the standards by designing the room composition e.g. external noise reduction which prevents excessive echo and sound resonating (resonance) etc.

Acoustic measurement for conference room

Generally, a conference room will be in a closed environment consisted of floor, wall, and ceiling. This situation may cause sound resonance, and/or insufficient sound absorption, which may have a negative impact on the sound quality communicated within the room. Thus, the room designer should pay attention to the acoustical properties as listed below:

Reverberation Time 60 (RT60) is the left-over sound when the sound source stops. If the timing is too short, it will cause an unlively sound that cannot convey a good tone of communication. For audio engineers, this type of room is called “dead” room. However, if the timing is too long, it will cause interference with the direct sound which will distort the intelligibility of the sound. This such room is called “live” room. Therefore, a good design of the conference room will have an appropriate RT60 value, suitable for the conference room.

Noise Criteria (NC) is a standardized value that indicates the level of room’s environmental noise. It is a property that is a result of the noise floor measurement in an objective manner. The unit measures the noise level inside a room or building, first established by the acoustics expert ‘Leo Beranek’. The standardized value indicates the degree of combined noises from motorcycle passing by, raining, thunder, walking, talking, and object impact sound, which construct the noises inside the room. This acoustical property, if is excessive, can be controlled through a proper design of acoustic materials and their positioning on the floor, wall, ceiling, and/or roof.

Speech Transmission Index (STI) is the quality of the sound transmission between the source and the receiver of sound. The figure is between 1 (only ideally excellent) to 0 (worst).

Rapid Speech Transmission (RASTI) is the quality of sudden speaking sound transmission. Its principle is similar to the STI, but it only measures two frequency octaves, so the result is a little bit different from STI.

Sound Pressure Level (SPL)
The unit of SPL is dB, used to measure the loudness of the sound in a conference room. The quantification should be done at various spots of the room that the audience will be located to ensure the uniformity of the sound level across the listening pane.

Proper criteria set as the design goal
A room designer should consider these acoustical properties when designing each type conference room. Also, the designer is to set proper values and criteria for designing and managing the acoustic materials by using acoustic simulation and calculation to ensure that the design will comply with the pre-determined acoustic values.

The examples of acoustic values determination.

  • RT60: 1.4-1.9 Sec
  • NC: NC-30-NC-35 or 38-42 dBA
  • STI: Greater than 0.66
  • SPL: Peak SPL greater than 80 dB

Necessary tools for acoustical measurements for conference room
Instrument: TEF25 Analyzer

  • A laptop with SOUND LAB GOLD LINE software
  • Measurement microphone according to the property and type of measurement
  • High-quality cable
  • Audio system

 

Instrument: NTI Audio & Acoustics Measurement Device

  • Sound Level Meter
  • Spectrum Analyzer / Real-Time Analyzer (RTA)
  • STIPA Analyzer
  • Audio Analyzer
  • Digital Audio Analyzer
  • Vibration Meter
  • Projector PRO Software
  • Measurement Microphones
  • Class 1 Sound Calibrator
  • Manufacturer Calibration Certificate
Image: http://www.gold-line.com/tef/t-tefkit.htm

 

Instrument: NTI Audio & Acoustics set

  • Sound Level Meter
  • Spectrum Analyser
  • STIPA Analyser
  • Audio Analyser
  • Digital Audio Analyzer
  • Vibration Meter
  • Projector PRO Software
  • Measurement Microphones
  • Class 1 Sound Calibrator
  • Manufacturer Calibration Certificate

Instrument: Noise Sources for measuring Room & Building Acoustics Set

  • Dodecahedron Speaker Set
  • Power Amplifier.
  • Tapping Machine
Image: https://www.nti-audio.com/
Image: https://www.nti-audio.com/