CMR3 calibrated receiver is designed for measuring the performance of audio hearing loop systems. The audio output is within ±0.25 dB over the frequency range and where used with a suitable audio analyzer such as the Minilyser from Neutrik Ltd, the frequency response and field distribution of the magnetic field from any audio hearing loop system can be plotted. Calibrated to provide 0 dBu output for a field strength of 400 mA/m RMS, in accordance with the international hearing loop standard IEC60118:4. It is an essential tool for anyone wishing to assess loop system performance for analyses or certification.