Do you get a message to End Task on onenote when PC is trying to go into
standby?

If not, then I don't think it's a software problem.

The leading cause of standby/hibernation issues is a driver that doesn't
support it. A secondary cause is a driver that is corrupted or possibly in
use (badly written driver?)

If the problem is associated with audio files then perhaps you need to
update your audio driver. Do you have any hardware connected to any ports
that may not support standby/hibernation, for instance an older device like
scanner, camera, drive, printer, etc?