I believe that's actually slowed down. The actual signals detected lasted for something like 0.25 seconds, IIRC. And that's not really the sound, of course. It's just the audio equivalent of the frequency of the gravity waves. Each wave corresponds to 1/2 of a rotation of the black hole pair.
I don't know exactly what it would have looked like, exactly. Visualizing black holes is still in its early days. I mean, think of the black hole in Interstellar; the studio basically bought a pimped out GPU cluster in order to render that thing at the low, low cost of 10s, if not 100s, of thousands of dollars. For the most part, it would look like two black, kinda shiny balls orbiting around each other, getting closer and closer, and their orbits getting faster and faster as they approach, until they touch event horizons and just kinda "slurp" each other up, like connecting water droplets.
Kip Thorne is the man who provided the black hole model for Interstellar, by the way, and here is a video of Thorne discussing the collision of black holes: https://www.youtube.com/watch?v=42cqhjmt4vs
If you fast forward to 4:20, he has a rather bare bones simulation of a black hole merger (and you can see the gravity wave profile at the bottom of his video, which is what was used to make that "whoop" sound!)