This Recommendation defines a method of subjective assessment of transmitted speech quality for long speech sequences containing quality/time fluctuations. This method is based both on a continuous rating during the listening of a speech sequence and on an overall rating at the end of the speech sequence. Therefore, in addition to the measure of the overall perceived quality (as with the generally recommended methods), it provides a measure of the instantaneous perceived quality, i.e., the quality perceived at any instant of a heard transmitted speech sequence. In its current version, this method is not applicable to the selection of speech codecs. However, it is a useful tool to diagnose the effects of impairments on instantaneous and overall perceived quality, especially for discontinuous impairments with temporal fluctuations (e.g., those due to IP packet losses, handover in mobile networks, etc.). It can also aid the development and the validation of objective measurement tools that aim to predict the speech quality by detecting and analysing various types of impairments present in a speech signal; in fact, the Continuous Evaluation of Time Varying Speech Quality (CETVSQ) method can provide instantaneous judgments, as well as an overall evaluation of the subjective quality.