ITU-R Recommendation BS.1116-1, Methods for the Subjective Assessment of small Impairments in Audio Systems including Multichannel Sound Systems, 1997

This Recommendation is intended for use in the assessment of systems which introduce impairments so small as to be undetectable without rigorous control of the experimental conditions and appropriate statistical analysis. If used for systems that introduce relatively large and easily detectable impairments, it leads to excessive expenditure of time and effort and may also lead to less reliable results than a simpler test. This Recommendation forms the base reference for the other Recommendations, which may contain additional special conditions or relaxations of the requirements included in this Annex.