This Recommendation describes procedures to be used to assess the subjective performance of echo cancellers. The methods defined here may be used to assess the extent to which an echo canceller operates effectively for voice users of the PSTN. In particular, the intent is not to define methods that may be used to assess the effects of delay, nor is it the intent to define rules for echo canceller application. These issues are addressed in Recommendations G.114 and G.13 1,respectively. Further, this Recommendation does not define specific values for echo canceller parameters (e.g. convergence time) to yield satisfactory subjective performance.