Double-click the desktop icon to open Pro Tools.
Click "File" and select "Open Recent." Select the relevant track from the drop-down menu.
Click "Options" and check "Pre Fader Metering." This provides metering information while the track is not record-enabled, permitting you to view the energy patterns of the audio regardless of the channel status.
Click "Plugins," "Sound Fields" and select "Digirack Phase Scope." The Digirack Phase Scope will open in a new interface, which approximates the appearance and functionality of a hardware phase scope.
Drag the scope interface onto the "Stereo Out" channel. This way, the scope meters the entire audio, rather than a single track.
Drag the orange arrow to any point below "0-db." In mastering, "0-db" refers to the loudest peak in the audio. Setting this as the limit would assign "loudest" as the default threshold. Each volume spike would reset the threshold and you'd have no way of determining whether things were too loud. The peak and average output are a matter of preference and depend on your own taste. While a high level will be louder, it can affect the dynamics of your audio. Once you've set the level, the Phase Scope will tell you if and when that threshold is exceeded, enabling you to take corrective action such as applying automated compression to the loud part.
Hit "Play" so a stereo signal feeds into the Phase Scope.
Observe the meter. If the threshold is exceeded, note the point in the track where the violation occurred. This way you can fix that part of the audio later.
Click on one of the two stereo channels to highlight it. This configures Pro Tools so subsequent edits apply only to the selected audio.
Click "Audiosuite," "Other" and select "Invert Plug-In." This reverses the polarity of half of the stereo signal. To asses the phase of the stereo tracks, view the Phase Scope metering window. It should read "-1." If it doesn't, the tracks are out of phase. Fix this issue by reconfiguring any stereo expanders, master reverb or other mastering effects to the mix. Typically, reducing the delay time on a stereo expander eliminates phase problems.