I've been looking over the Half-Life 2 soundtrack, and there's one sample in the track "Lab Practicum" that I'm having a great deal of trouble finding. However, when I speed the track up by four times, I do recognise the sound from another game called Blockland.
Comparison:
Half-Life 2:
https://instaud.io/1HkG
Blockland:
https://instaud.io/1HkI
Blockland's sounds come from a CD the creator bought in 1995 from an electronics store, but the CD is nowhere to be found. However, from what I've seen around and from what I can tell by Blockland's other sounds, the CD tends to reuse sounds from other stock libraries, such as The Premiere Edition and the General Series 6000. This nicely coincides with Half-Life 2's composer, Kelly Bailey, tendency to use libraries like The Premiere Edition and Series 6000. He also uses libraries from Zero-G, Best Service, Spectrasonics, East West, and occasionally BFA or Sony Creative Software.
I've had a quick look through some early nineties stock sound libraries with no luck, so I'm posting here to see if anyone else might recognise the sample, or at least something similar to get any kind of clue at all. Any help with this would be appreciated!