I think I bought the same model, and wondered the same thing myself, but once I connected the two cables (SATA power and SATA data) I had sound. I think the SATA data cable must provide a connection to onboard sound.
If you have a separate sound card, I guess you may need a special SATA data cable that would allow you to connect sound to your sound card. From what I can see, there is no place to connect any audio cable to the drive. (I think the small pins on the left are jumper pins and don’t have anything to do with audio.) Good luck. Perhaps someone else can help you more.
Actually, I have different problem which I am also going to post. My CD ripping software (No. 1 CD Ripper) does not seem to recognize the SATA drive at all. Windows XP has no problems and Media Player plays audio CD’s, but this particular software cannot seem to “see” the drive at all. Is this possible or normal for SATA drives?