The audio tracks are synched with the video track. The system checks that the audio is in-sync with the video via the STC (system timecode). A thin red line will appear beneath the audio clip ruler:

SyncIndicator
Note
The actual shift of each de-sync is shown rather than the global video de-sync.

It is also possible to show the out-of-sync value by enabling the corresponding option in the "Timeline Preferences". Open the "Timeline Preferences" dialog box from the Timeline menu and select the "Show de-sync value" checkbox:

nf128_129_updated

When the "Show de-sync value" function is enabled, the sync values are displayed in white; negative values are displayed at the beginning of the red bar; and positive values are shown at the end of the red bar.

Note
If Timeline is not active, then the de-sync indicator is not visible and the values are not shown either.
Note
Tracks that are deselected from monitoring will be ignored by the de-sync indicator.