In addition to simultaneous masking two time domain phenomena also play an important role in human auditory perception, pre-masking and post-masking. The temporal masking effects occur before and after a masking signal has been switched on and off, respectively (Fig. 7). The duration when pre-masking applies is less than -or as newer results indicate, significantly less than-one tenth that of the post-masking, which is in the order of 50 to 200 msec. Both pre and post-masking are being exploited in the ISO/MPEG audio coding algorithm.
