J.K. Rowling has stated that Dumbledore was fluent¹ in English, Mermish, Gobbledygook, and Parseltongue. If this is so: Why didn't Dumbledore hear the Basilisk during the events in Chamber of Secrets? There's nothing to indicate Dumbledore was hard of hearing (no ear trumpet!) and he spent enough time in the castle that surely he would have been near the Basilisk at least once or twice. Is there any canon-based explanation for this?
¹What J.K. Rowling actually said was that Dumbledore understands Mermish, Parseltongue, and Gobbledygook. That's enough of a difference from fluency that I felt I should mention this. Further, J.K. Rowling has this to say about learning Parseltongue:
Q: Since Ron is able to speak Parseltongue in the last book, does that mean that Parseltongue is a language that most witches and wizards can learn or must a person be born with some ability to speak Parseltongue?
JKR: I don't see it really as a language you can learn. So few people speak it that who would teach you? This is a weird ability passed down through the Slytherin blood line. However Ron was with Harry when he said one word in Parseltongue, which I do not know so I cannot duplicate for you, but he heard him say "Open," and he was able to reproduce the sound. So it was one word. Whether he could learn to speak to snakes properly is a separate issue. I don't think he could. But he knew enough, he was smart enough, to duplicate one necessary sound.
[ J.K. ROWLING AT CARNEGIE HALL - 10.20.07 - TRANSCRIPT FROM THE LEAKY CAULDRON ]
So where does this leave Dumbledore when it comes to Parseltongue?