The ITU Radiocommunication Assembly considering that the introduction of new kinds of sound signal processing, such as digital coding and bit rate reduction, new kinds of television signals using time multiplexed components and new services such as enhanced television and high definition television (HDTV), may require new or amended methods of subjective sound quality assessment; that these techniques entail their own specific signal impairments; that subjective listening tests permit assessment of the degree of annoyance caused to the listener by any impairment of the wanted signal during its transmission between the source and the listener; that many different methods of subjective testing are possible; that it is highly desirable to standardise the methods of subjective testing and the interpretation of the results, so that the best possible comparisons may be made between results obtained at different times and/or in different places; that it is highly desirable to standardise the methods of subjective testing and the interpretation of the results, so that the best possible comparisons may be made between results obtained at different times and/or in different places; that it is highly desirable that the grading scales which are used to describe the subjective quality of sound should permit more consistent statistical processing methods, independent from the language used to express the opinions; that it would be desirable for a single assessment scale to be available for both sound and television programmes; that the geometric and acoustic properties of control rooms and listening rooms can have a considerable influence on audition, and therefore listening conditions should be closely specified.
ITU-R BS.1284-1 SPANISH-2003 Referenced Document
ITU-R BS.1116 Methods for the subjective assessment of small impairments in audio systems*， 2015-02-01 Update
ITU-R BS.1283 A guide to ITU-R Recommendations for subjective assessment of sound quality*， 2003-12-01 Update