Hi, article author here: it was the pitch shifting behaviour in particular that I wanted to explore when I modified the random table. Early versions of doom (<1.4) did it, but they accidentally removed that feature with a rework of sound code in 1.4 and onwards (including all versions of doom 2). It was originally applied to all but two sound effects, with special casing for chainsaw sounds (less variance afaik).
There were, however, three distinct zombie death noises, independent of pitch shifting.
Interesting! Are the three zombie death sounds perhaps speed-shifted versions of the same original? My recollection (it's been a while) is that zombies made dramatically different sounds on death but--once I started looking for it--they all seemed to be speed-shifted versions of the same sound, while pitch-shifting in other sounds was subtle enough that I never noticed it. If pitch-shifting normally applied equally to most sounds, that implies that there was something else going on with the zombie noises I recall.
Or maybe I'm completely confused because I haven't played it since the '90s. Might be time to give it another try...
There were, however, three distinct zombie death noises, independent of pitch shifting.