Acoustic measurements in an anechoic chamber

Acoustic measurements in an anechoic chamber

Anechoic chamber

This acoustic chamber is built in such a way to minimise the level of acoustic background and acoustic waves reflected from the walls and limit the external noise. Sounds from the outside are strongly suppressed due to the walls’ acoustic insulation and the materials used. Internal surfaces are covered in material with strong sound-absorbing properties; the chamber is lined with “porfles” tiles. Lighting and electricity, together with a table allowing set up of the measuring apparatus are located inside the chamber.

Chamber specifications

  • Internal dimensions: 3,8 x 6,8 m, height 2,5 m
  • Usable volume: 73 m3
  • Chamber acoustic background: 20 dB (A)

Norms

  • Determination of sound power levels and sound energy levels of noise sources using sound pressure – survey method using an enveloping measurement surface over a reflecting plane (PN-EN ISO 3746).
  • Determination of sound power levels and sound energy levels of noise sources using sound pressure – engineering methods for an essentially free field over a reflecting plane (PN-EN ISO 3744).
  • other industry norms (manufacturers’ own)

Analyses

  • Frequency analysis (FFT, CPB, FRF and others)
  • Time analysis (time domain)
  • Order analysis
  • Overall
  • Graphs as a function of time, rotational speed, frequency, order, etc.

Measuring apparatus

  • We use DAQ equipment from companies such as: Brüel&Kjaer, OROS.

Converters

  • polarised (200 V) class 1 microphones (Bruel&Kjaer and G.R.A.S.)
  • class ICP 1 microphones (PCB)
 

Measuring apparatus

Document No. Title/Description
PN-EN ISO 3746:2011 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Survey method using an enveloping measurement surface over a reflecting plane
PN-EN ISO 3744 Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Engineering methods for an essentially free field over a reflecting plane