Yes, it can play MIDI songs. Be sure that you have enabled some audio card in the configuration of the game (preferably the Soundblaster). If I remember correctly, it was enabled by default, but it's better if you check it.
I don't know "Taiwan karaoke". If the sound card is enabled, maybe the problem is in the program. If you can have access to the configuration needed for this game (IRQ port and so on) you can see if the configuration of the Soundblaster that Dosbox is emulating, is the same. Also, check if Taiwan karaoke uses filenames with asian characters (I guess that dosbox will not manage these files well).