You probably did not know that when you kill a Viper in XCOM 2, what you hear in its final seconds is a howling baby. But that's what it is, according to Lead Audio Designer Chris D'Ambrosio, who described it in a new blog post as "a pitched-down baby's scream, which is completely unnerving."
"A baby crying is very interesting because the sound is a frequency our hearing notices above most other things," D'Ambrosio explained in a brief, interview-style discussion about the creation of XCOM 2's audio. "To then pitch it down becomes so off-putting. It works perfectly! Movies have also set the precedents that snakes make a high-pitched screeching noise. The challenge with the Viper was to take a high-pitched screech and make it big."
"Big" was also a factor in the creation of the Berserker's yell. D'Ambrosio said he watched the animation of the Berserker's initial reveal four or five times after it was first given to him, "to understand the motion of the animation and to start figuring out the size of the sound she should be making." And even though it's an alien creature, he said making use of recognizable sounds, which in this case included a pig, an elephant, a tiger, a tornado, a flamethrower, and a bit of bass drop, helps players "understand the size, weight and in this case, the damage this thing is going to do."
The Berserker and Viper audio clips are embedded below. Sadly, a third clip, created by rubbing a wet lacrosse ball on a carpet, is not, so instead we'll make a game out of that one: Can you guess what it's for without looking?
XCOM 2 is slated to come out in November.