The on MIDIEND, on WAVEEND, and on MP3END events trigger when mIRC finishes playing a sound.
Format: on <level>:MIDIEND:<commands>
Example: on 1:MIDIEND:/splay jazzy.mid
on 1:WAVEEND:/echo Finished playing $filename
Triggers when a wave file finishes playing. See the Playing Sounds section for more information.
Note: These events will not trigger if you use /splay to play another sound or to stop a sound being played, they only trigger if the sound finishes playing completely.