Microsoft has released a new firmware update for the Surface Pro 4.
The update, which also brings Windows to Build update, 14393.479, only includes an update to the Realtek High Definition Audio (SST) audio Driver, taking it to version v6.0.1.7895.
The update offers “Improves system stability and Cortana performance“, presumably making her a better listener.
Download the update by Checking for Updates in Settings.