I had same problem, but only reinstall an audio device gave no positive effects. I've updated all of the drivers to the latest (dedicated for 8.1 on lenovo's suport webpage), and sound finally recovered. But the upgrade to Win8.1 and all of these driver updates cost me a lot - now I've recognised a serious problem with chopping and lagging of almost every application run in tent or tablet mode. It's a pity that such expensive device has no real suport several months after release. I've paid for it about 1100 EUR 3-4 months ago. Today I'll call the helpdesk in my country and try to know if there will be any solution for this matter. I guess it the only solution for this problem is probably downgrading to Win8.0 and in near future avoiding lenovo devices...