Microsoft has pushed a new firmware update to Surface Pro 4 Devices. The update is now available for download. It also brings Build 14393.479 to the Surface Pro 4.
Microsoft hasn’t introduced any new features with the firmware update. You will notice system stability and Cortana performance improvements. Realtek High Definition Audio (SST) audio Driver has been updated to version v126.96.36.19995.
Open Settings -> Update & security to get the update.