| a fundamental reference system of the CCITT comprising:|
the reference apparatus for the determination of transmission performance ratings or ARAEN;
a band-pass filter cutting off at 300 and 3400 Hz;
a device allowing specified electrical background noise to be injected at the input of the receiving system of the ARAEN
NOTE – The SRAEN is described in the CCITT Recommendation P44 from the Volume V of the Yellow Book, 1981.