How do Non-native Listeners Perceive Quality of Transmitted Voice?

This paper describes the test methodology and results of speech transmission quality testing in the environment of non-native listeners; it means the communication language differs from mother tongue of the test subjects. The tests have been carried out based on ITU-T P.800 on the database of English speech samples affected by various coding distortions and background noise conditions. The subjects have been pre-tested on their English proficiency. The subjective tests results confirm systematic and repeatable shift in subjective quality assessment performed by non-native listeners.