Type 4720

Echo Speech Source

Echo Speech Source quickly and easily performs speech intelligibility measurements in accordance with IEC 60268-16. 

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Echo Speech Sound Source outputs calibrated signals for measuring a range of speech intelligibility parameters in conjunction with DIRAC 6. The received signal is picked up by a microphone and analyzed in DIRAC, which calculates an accurate qualification of the speech intelligibility through various parameters such as the Speech Transmission Index (STI). 


  • Speech intelligibility measurements with DIRAC
  • Measurements including background noise
With a calibrated speech source there is no need for external 

equalizers or speech level adjustment. The signal can be set at an elevated level, making STI measurements possible - even if the background noise is significant. DIRAC 6 recognizes the output level and corrects calculations appropriately.

For STI measurements, it contains pink MLS signals. The MLS is far less intrusive than an e-sweep signal. In addition Echo Speech Source can be used to set the volume of PA systems using a male speech signal with a standard level of 60 dB(A) at 1 meter.


  • Wireless sound source for DIRAC 6
  • Fully calibrated sound levels and spectra
  • Mouth directivity

  • Five built-in stimulus signals
  • Intermittent stimulus accounting for background noise
  • External input and output
  • Compact and lightweight (10x10x17 cm, 1 kg)
  • Mounts on standard tripods
  • Battery powered
  • External power supply included