IEEE 661:1979 (R2008)

New IEEE Standard - Inactive-Reserved.
To describe a practical and reproducible method of determining the loudness ratings of telephone connections. Loudness ratings may be measured directly using appropriate test instruments and facilities, as specified in this standard, or may be computed using the amplitude-frequency characteristic of the connection measured in accordance with IEEE Std 269-1971. .

The procedures given in this standard may be used for determining the loudness rating of partial and complete telephone connections. For complete telephone connections, comprising overall and sidetone transmission paths, the procedures involve measurement of acoustic input and output pressures. For partial telephone connectiond comprising transmitting, receiving, or connection paths, the procedures involve measurement of acoustics pressures and electric voltages.
The purpose of this standard is to describe a practical and reproducible method of determining the loudness ratings of telephone connections. Loudness rating may be measured directly using appropriate test instruments and facilities, as specified in this standard, or may be computed using amplitude-frequency characteristics of the connection measured in accordance with IEEE Std 269-1971.