The manual hilariously instructs you to hook your hifi system up to the PC speaker, see the last page:
https://www.gamesdatabase.org/Media/SYSTEM/Microsoft_DOS//Ma...
Scream Tracker, a music composition software, was able to pull of the same feat, 4 channels of 8-bit voices, in 1990.
However cool and useful the PC speaker output was, it was the a hand-soldered "Covox" lookalike, a passive DAC built out of a resistor ladder and attached to the printer port, which you actually connected to your hi-fi amplifier.
Worth noting that the quality in these cases was pretty good. A bit staticky but still well above Wolfenstein 3D sound effects most people associate with PC Speaker (covox-less).
Edit:
This sent me down a rabbit hole and I found this nice video about PC speaker history: https://youtu.be/jD4m9JvLy2Y
The beep-speaker music in Commander Keen was good and fit the theme of the game - but to keep the environment of Doom and the dark and moody feel and not be limited to the dulcet tones of a tiny piezo buzzer was a design decision, not being lazy.
Note that they could have supported Disney Sound Source / Covax Speech Thing style audio (they did in Wolf3D and Keen) but skipped that as well, likely for the same reason - it would have sounded like murky hollow garbage.
You can email John Romero and ask him, he responds to emails - my guess is that he will say "yeah we considered it, it sounded bad, we abandoned the idea" not that they were lazy. If you read about the run up to Doom's release, and the amount of crunch time they were putting in, they were anything but lazy!
They are lifted as is from Shadow Knights.
> which is to say "as good as they can be, but still bad"
They could be done better or even way better, it's just that wasn't an important target in any way. Especially considering the performance target of 486DX+ whicih wasn't not a cheap machine in any way in 1993.
I think they could have made something a lot better by, like Wolf, dropping music entirely from the PC speaker implementation. Focus on the sounds that matter.
This even happened on the SNES. A few Square games like Chrono Trigger and Final Fantasy 6 have tracks that are noticeably missing a music channel when playing sound effects. It wasn't totally necessary to use all the channels, but they were very adamant about their music quality.
I recall a special Windows 3 driver could push sound effects and music through PC speakers, at least those which were an actual small speaker embedded in the case. It was very rough and mono but a neat trick. I don't think it worked with the coin sized beepers in older models.
Still neat.
I recall Windows 3.1 was sometimes shipped with a speaker driver that could emulate a very basic audio card on a traditional PC speaker almost entirely in software.
Amazing .mod based techno music via pc speaker that mixed in sound effects, even including short vocal clips (pkunk insults). All running on a humble 286 which played the game well while managing this. For those that say this was a choice due to poor pc speaker quality the toys for bob engineers pulled it off with incredible results years prior.
It was just a pain to do.
Just doing a little research it was like $80 - $100 to add it.
I do remember back then that the motto was for PCs that “the computer wanted was always $2000”.
My first time having an x86 PC was in 1994 when I bought the 486DX/2-66 DOS Compatibility Card for my PowerMac 6100/60. It had a SoundBlaster daughtercard.
Also you don't have $100.
The motherboard on the Mac had an internal audio input slot you connected the CD player to for audio CD playback. You also connected the DOS card’s SoundBlaster daughtercard directly to the motherboard and you could play PC sounds directly through the Mac speaker.
Before that, there really wasn't much else you could do with them other than games. The original Soundblasters were fairly crap - mono 11kHz 8 bit sound - so they weren't exactly hifi. There was better kit available for professional use from the likes of Gravis and Turtle Beach, but the price put them out of reach for most home users.
Meanwhile, 8 year old Amigas were playing 12 bit digital stereo sound on 4 channels … on a preemptive multitasking system on a machine with less RAM and a < 8Mhz CPU.
That's when I first became enamoured with the "art of the possible" and this has driven my career.
I fully believe that doom could have had pc speaker sound; after all w3d did!
Good job, it sounds great!
The original source code for DOS got reverse-engineered here: https://repo.or.cz/doom2d-restoration.git (discussion: https://doom2d.org/forum/viewtopic.php?f=8&t=2996 )
I still remember being shocked by the FX sound from my PC speaker. That was before I got enough money to buy a SoundBlaster-compatible card.
While it might have been possible to add PC speaker music, would it have been worth the effort at the time? How much would it have delayed the release of the game? Would anyone have cared very much about being able to have terrible quality music on their PC speaker?
So they'd have had to extract this feature from a vendor where the relationship is already breaking down, or ditch it all and start from scratch with a new vendor, or inhouse code.
[id Software was Lazy - DOOM could have had PC Speaker Music!]
On Linux, `sndserver` is a separate process. On MS-DOS, it was not. On DOS, priority mixing would have to happen e.g. within Doom's tick processing or in the sound interrupt handler.
If you're just making these changes in Linux and assuming they could have worked in 1993, you're just cosplaying.