What is voice ? what is speech ? what is language?

https://www.nidcd.nih.gov/health/what-is-voice-speech-language

Voice

Voice (or vocalization) is the sound produced by humans and other vertebrates using the lungs and the vocal folds in the larynx, or voice box. Voice is not always produced as speech

Speech

Humans express thoughts, feelings, and ideas orally to one another through a series of complex movements that alter and mold the basic tone created by voice into specific, decodable sounds.

Language

Language is the expression of human communication through which knowledge, belief, and behavior can be experienced, explained, and shared.

Speech and language are not the same thing. Many deaf people are unable to speak  but are perfectly able to communicate by gestures which form the sign language.