Deaf-mute

Deaf-mute is a term which refers to deaf people who cannot speak a language. They cannot speak by mouth. Or, they may choose not to speak because of the attention unusual voices attract. 
They communicate using sign language. 
Today some prefer simply "deaf". However, it may be important for others to know whether a deaf person can speak, even imperfectly.
There is a complete range of intelligence in deaf-mutes. However, the limitations of their language ability may have an effect on their understanding of the external world. Many live communally amongst others who are expert in using their particular sign language. But sign languages differ greatly between countries, and may also differ inside a country.