Hmm... I never had any trouble picking out "pressure equalized" but I have certainly had times where I heard things wrong. From memory, the monotone voices go:*Snicker* You've reminded me how I misunderstood that "PA" voice. For several years, watching the edition that aired on HBO in the early 80s, I found myself scratching my head over the seeming gibberish, "Pay cure bee quad." Maybe I was just incredibly "dense"; maybe the audio mix for that copy was just a bit off. Upon watching on VHS, maybe the DVD (before the "Director's Cut"), I finally realized that disembodied voice was saying, "Pressure equalized," in response to a successful docking.
D'OH!!!
"Pod secure" - "Pressure equalized"
"Attention launch crew, a travel pod is now available at cargo 6. Travel pod available... cargo 6"
"Engineering to all decks, auxiliary power test in three minutes... mark"
and I've always had a fondness for the original theatrical release alert sound, with the mechanical "Emergency alert, emergency alert, emergency alert" calling over it.