Not necessarily. There was a lot of experimentation at the time and things that did hacky things like blip the mono speaker at different frequencies to produce interesting sounds were not out of the question.
I remember a demo at my Commodore 64 users group one day...a guy loaded a bunch of stuff from a disk and output (with sound quality not that much worse than a car's crappy AM radio speaker) the first 10 or 15 seconds of "Kung Foo Fighting." Of course, the C64 had the VIC chip, but it was still freaking impressive.
You’re right, this was used to great effect in Castle Wolfenstein - where the guards would shout “Achtung” in German.
If you accessed (either read or write) memory address $c030 it would move the cone of the speaker in or out. Do it fast and you can create tones and voices.
