Talking is actually a sensitive topic. The vocal cords of most deaf people are perfectly fine, so they can make sounds that a blind person could hear.

Some deaf people speak perfectly clear. This could be because they were born hearing, but became deaf later in life, through a disease or accident. Or because they have been (brutally) forced to learn to speak as a child. In some countries forcing a deaf child to learn to speak and to read lips, and taking away the option to learn sign language, is legally considered a form of child abuse.

Some deaf people speak with a deaf accent. This is because they don't hear their own voice. It is many times more difficult to (learn to) speak, when you don't get that feedback.

Some deaf people can speak, but choose not to. This could be out of principle, or maybe because they have been bullied for their deaf accent, or maybe because hearing people will automatically assume that a speaking person is able to hear too.

Some deaf people never learned to speak. This does not mean there is anything wrong with their voice. They simply have a another language in which they can communicate. Nowadays there are a lot of ways for deaf people and hearing people to communicate without the need for spoken language.

And I'm sure somewhere on this earth there are people living who are both deaf and mute, who actually don't have the ability to speak.

So be mindful when talking about the speaking abilities of deaf people

I think this way of communication is the most likely, especially if the two persons aren't acquaintances.

Sign Language interpreters are people whose job it is to interpret (convert/translate) between spoken language and sign language, to aid deaf people and hearing people with the communication gap. A blind person and a deaf person can ask the aid of a sign language interpreter. This allows them to communicate in their preferred language.

They can communicate. They can use something called "tactile signing". It's a form of sign language where the other person uses their hands to feel which sign you are making. Tactile signs are often used by people who are both deaf and blind: https://youtu.be/9GrK3P15TYU

Or they can communicate using a written language, like braille

Oxygen is very dangerous to most part of the body and death is just a withdrawal effect