This one actually has the answer to a puzzle in it, but I found myself skimming over the rest of the material. It's very tedious to read hand-written stuff on a PC screen. At least there wasn't as much of this material to read as there was in Myst, and if you can manage to get stuck into it, you should piece it all together by the end. The ambient sounds are extremely well done. When you turn a steam valve, you are rewarded with a satisfying hiss.
Doors creak open and shut.
There are loads of animal and insect sounds. I was somewhat less enthused by the music, the quality of which is superb, yet no single piece really stood out from the rest. It was really just one continuous melody that went a bit up-tempo when you did something significant, and then calmed down again when you moved off to another area. Film soundtrack quality, though. Overall, the sounds that emanate from the world of Riven are some of the best that I've heard in a computer game.