When implementing the correction of relative timing difference or error of sound and vision signals, the following user requirements should be satisfied. In the case of on-line correction of the timing error of sound and vision signals, the audio quality of the sound signal when observed at the output of the sound signal timing corrector, should be maintained at the start of, during and at the end of the correction, with the quality of 4.5 or higher, when evaluated using the subjective evaluation method based on the ITU-R five-grade impairment scale and the results are presented using the diffgrade.