Do you remember that impressive Half-Life 2 mod where a chap replaced all the sounds with new versions he'd made himself with his mouth, lips, tongue, saliva, and perhaps other parts of his gastrointestinal tract? What a silly sausage! Now someone has done the same for Doom. Shotguns, rockets, growls, elevators: you name it, they've recreated it with their mouth. What could be more Doom-y than an offering of flesh and spittle?
All the bangs, spits, clicks, chhks, chik-chuks, pows, booms, whooshes, whines, zips, and whips of Doom (and Doom II) can be yours in the mod humbly named "Greatest sound .wad ever" if you head on over to Doomworld's list o' mirrors. Yes, creator 'Mallo' remembers John Romero's little cameo at the end of Doom II too.
The mouth sounds mod is a charmingly simple idea. Haven't we all enjoyed making obnoxious noises? Folks have released similar mods for Quake, Minecraft, and goodness knows what else too. I imagine this isn't the first for Doom either, but it is the one I found and played last night. Yes, it's a load of silliness, but I played a good few levels of Doom II before the novelty wore off. I especially like some of the unintentionally(?) cute growls.
Here, open your lugholes and listen to the start of Doom II with this mod. Then I started larking about with cheats to test the bigger guns. I am both surprised I can remember every secret in Map01 and appalled I've forgotten the lot in 02. For shame.
Or if you want more serious new sounds, someone has just released a mod with high-quality versions of the PlayStation Doom's sounds (which sound like this). Or you can have a mod recreating that bleepy-bloopy PC speaker style. That's just the tip of the soundberg, of course.
If you've got Doom on Steam, by the way, do look into using a community-updated engine rather than that clunky DOSbox setup. ZDoom is a solid choice with support for high resolutions and whatnot (or get a nightly build, as it hasn't had an official release in yonks), and Chocolate Doom is a very conservative updating for purists, while Doomsday is the shiny-shiny opposite.