How is all this possible? Are they completely deaf, do they just feel the music (vibrating air) on their skin/stomach? Whats a meaning of a melody for them? Or of harmony?
He seems to wear a hearing aid, so he isn't profoundly deaf. According to Wikipedia he's 90% deaf. His parents bought him a drum set after noting him react to music on the radio. (Just what the world needs, another deaf drummer :-)
Beethoven went deaf in later life. Whether profoundly deaf or not, I don't know.
And there's this lady, who as well as having a successful musical career, seems to have thoroughly enjoyed her personal life!
The musician's ear worm Audiation might be what you are looking for. My brother in law can hear the music in his head solely by reading the score. I'm trying to develop that skill.
If you go deaf early in life you can't understand true melody and harmony. You can feel vibrations, but that's not an acoustic experience. I don't know about the guys you mentioned, but let me explain a composer's case.
Beethoven (and Faure) went deaf later in his life. A composer learns the harmonic and melodic patterns and just knows how they sound in their head. When they read or write music they don't need to hear it - they know how it sounds.
Try it yourself with a reading book - read the words in your head, you can actually "hear" them since you already know what they sound like. You are familiar with the sounds produced by the combinations of letters. A good deaf composer can write music just as well as a deaf writer can write word-based works. Depends on how proficient you are with music, come up with a melody in your head (don't sing or play it), take a sheet of paper and write it down. That's it. Deafness doesn't hinder you that much once you have a good image of how music sound.
Players on the other hand can't play if they are completely deaf. There are many minute pitch and tempo corrections your brain does "automatically" (to some extent) by hearing the players around you, or even the previous note you played. Don't know about drummers, but I have a feeling even they need to listen to what's going on around them.
So: (experienced) composers - yes, conductors and players - no.