Speaking and talking are colloquially used to describe people communicating in sign language. “I speak ASL”, “I talk ASL”, etc.

Definitions of the words speak and [talk](www.merriam-webster.com/dictionary/talk] cover non-verbal communication.

Speak: to express feelings by other than verbal means

Talk: to express or exchange ideas by means of spoken words or sign language

That said, I agree that OP was likely asking about spoken word.