Method for automatically controling volume level for calculating MOS

The present invention relates to a method of automatically controlling the volume level of communication speech for Mean Opinion Score (MOS) measurement, which, before evaluating the quality of communication speech using a MOS measurement method, automatically controls the volume level of actual communication speech to a predetermined optimal level, thus improving the reliability of MOS values.The present invention provides a method of automatically controlling a volume level of communication speech for MOS measurement using MOS measurement equipment, the MOS measurement equipment calculating an MOS value based on results obtained by comparing a speech signal, which is received via a voice communication network, with a reference speech signal, the method comprising the steps of (a) when an audio signal, including a speech signal, is received from counterpart MOS measurement equipment in a predetermined format, measuring the volume level of the speech signal and comparing the volume level of the measured speech signal with a reference volume level; (b) transmitting a predetermined intrinsic audible frequency signal, which corresponds to 'proper,' 'excess' or 'insufficiency' information resulting from the comparison, to the counterpart MOS measurement equipment; and (c) the counterpart MOS measurement equipment interpreting the predetermined intrinsic audible frequency signal, which corresponds to the 'proper,' 'excess' or 'insufficiency' information, and controlling the volume level of the communication speech.