I have been successfully able to run Day of the Tentacle with DOSBox & D-Fend. Earlier this year, I was also able to run the game fine using some sort of combo with VDMsound or something like that, but had the same results.

The game will open up with the pleasant intro with all of the sound and graphics, and Bernard tells Hoagie and Laverne to split up with the dialogue and background music. After this, the background music continues playing, but instead of dialogue when controling Bernard, all I get is subtitles of what he is saying.

My copy of the game is not legal unfortuantely because I lost my old copy that was on a CD. Are there any known fixes to this problem? I have this exact problem while trying to run Monkey Island 1.