Thread:Deathstalker666/@comment-1496755-20151224121621/@comment-1496755-20160406064241

Adlib sound effects - Wolf 3D had them too, some of them are heard even if you have Sound Blaster (the treasure pickup sounds, for example). Thy aren't really cheap, but rather limited - this card had a certain variety of "beeps" and "boops", so one had to work with that.

Doom never bothered with Adlib sound effects - it had some basic PC Speaker stuff, the rest was digitized Sound Blaster effects.