Summary: A side effect from NOS-4-A2's bite leaves Ty hearing things that no other organic can.
The voices were almost haunting in their consistency and words, but he did his best to ignore them. The last thing he needed was for people to think he was crazy for hearing them, and it took Ty himself quite a while to determine he wasn't crazy at all. Just another side effect of the bite from NOS-4-A2, he determined. Just another thing to make his life weirder than it already was.
It was a well kept secret from other organics, apparently. Robotic kind had their own private channel to talk to each other and share secret thoughts and feelings. Only they could hear it, and only they could communicate through it. As Ty found out, he could now do the former but thankfully not the latter. He could now hear the personal conversations of robots as they passed him by. He could hear the secret insults and praise they shared about organics.
He could hear their worry that he might change into the Wirewolf and attack them again. Whenever there was a pair of robots near him for an extended period of time, one would eventually cast a fleeting glance at him and then share with the other their worries about what Ty might do to them.
It was haunting, yes. He was learning to live with it and he wasn't sure what to do should someone find out. But until then, he just had to pretend as if he couldn't hear those voices that no other organic knew existed.
Notes: If you read my short story "Life's Not Fair" you would recognize the idea of the robots' private channel from that. The idea here is that, under the headcanon that NOS-4-A2 injects nanobots into his victims which then bound to Ty's cells, the nanobots allow Ty to hear this private channel, but since he's not a robot he can't actually communicate back.