how does a baby with two deaf parents learn to speak?

Well, when a baby is born they test the hearing in the hospital. Most deaf people have a lot of hearing friends and family, so if the baby is able to hear they just make sure the exposure to others is high and usually get a speech therapist after a certain age to help them. And don't underestimate television and radios. And remember, just because someone is deaf doesn't mean they are mute. Some deaf people even learn to talk to a point themselves (like Helen Keller.)

Now, as far as hearing a baby cry, they usually have a noise sensor. Like, most of the monitors you see these days have a light display that lights up if the baby is making noise. They have things like that, they have beepers that vibrate when a noise is being made, and many new parents invest in a hearing-aid dog (they're not that hard to train and almost any breed can be used, some cats even. You just teach the dog to run to the source of noise (like crying), then back to the owner, and back and forth until the owner reaches the source of the noise at which point owner gives a treat. VERY VERY easy to train.) Or they go the old fashioned way and put the baby next to them a lot, carry them around a lot, and if they sleep make sure that the bed is easily jostled if the baby cries.

There are many other resources. We only know her parents are deaf, so we may assume, since it's unstated, that they are not mute.

After my daughter was born (we both speak and hear) we used to leave a radio on in her room so she would hear voices even if we were not speaking. It was hoped she would develop faster. Must have worked, for years she never shut up. <Joke>.

Any social or formal interaction is an opportunity to develop skills, and the more a person is exposed the greater the opportunity for advancing skills.

A deaf person can learn to speak. As an example, I reference Lou Ferrigno (Incredible Hulk). Listen to the WAY he speaks; it is because he never heard how words are supposed to sound but he has been taught. Thus his speech is not 'fine tuned', but he can certainly communicate, even if he is limited in his reproduction of tone.

My wife and I are deaf and we relied on TV for our daughter to learn how to talk. She now talks like Barney and Sesame Street characters.

babies around other people but their parents. im sure its from grandparents aunts uncles etc. plus if they go to daycare theyll be around people speaking on a normal basis. the death can talk its harder and their voice doesnt sound like everybody elses obviously and its harder for them. any one of those things could be it. im curious about how they raise them too because they cant hear the baby crying at night

do you have other children or siblings who speak? Have your baby around them a lot. If you don't have either, hire a house sitter to be around your child and talk to her/him. Take them out to the store with you and in public places where there is a lot of talking.

Other family and friends. I don't know if you have seen the episodes where her and Gibbs talk about Tony or Mcgee in sign language... pretty funny.