Probably not what everyone would consider sci-fi, but if you can find the abridged versions (*stay with me) read by Tony Robinson, the Discworld audiobooks are really enjoyable to listen to.
Good Audio Sci-Fi
- Snow Crash
- The Martian (more fictional science than sci-fi, but still excellent)
- Ringworld series
- Beyond the Blue Event Horizon
*Unfortunately, the unabridged versions were read by Nigel Planer and Stephen Briggs and neither of them capture the characters in the same way Robison does.