For transmission 6, when asked how long you can survive without air I entered "Two minutes" and got results: the female voice said "Just because you're breathing doesn't mean you're alive", then the male voice asked "What sense are you willing to lose first?" I entered "Sight", and unlocked three nodes: what appears to be a bust of Plato and two I didn't recognize. I tried to upload the images, but I got some kind of permissions error.
Transmission 6 - Cthulu references
As prevously mentioned, I also noticed the exact same response after typing in "10 minutes"", after which I also answered "sight". The three nodes showed Hieronymus Bosch, Plato and an image of the Wheel of Fortune (ca. 1497). After typing in "ship of fools", which is the source of the image of the wheel, the male voice asked: "What does the face of God look like?" My answer of "old man" prompted the voice to say "The key and guardian of the gate past, present,future all are one in...". This is a reference to Yog-Sothoth. To quote Lovecraft: "Yog-Sothoth is the key and guardian of the gate. Past, present, future, all are one in Yog-Sothoth." This was followed by the sixth audio log.
Interestingly enough, the audio file containing this line is called "Q5-12-yoshi-yog-little-brother.mp3", and I was a bit surprised to see "little brother" in there. In the Cthulu-mythos, Yog-Sothoth is a half-brother to Cthulu, but a reference to "Yog Sothoth's little brother" can also be found in Wolfgang Hohlbein's The Hexer from Salem - Witches of Salem: Episode 3, where the little brother is identified as a shogoth.