When the Avengers storm into the HYDRA base they look at all the cells Steve: "I heard they experimented on kids here... but there's no one left"

Tony: "Mm, I don't know, let's just look further."

When they open a cell they see a small child, she looks quite startled by the sudden people coming in

Clint: "Hey kid... are you okay?"

*You just stare back at them

Natasha: "Clint, I think she's-"

Wanda: "She's deaf."