The Audio Track Editor shows a close-up view of part of an audio track in the Tracks area, displaying the audio waveform of the regions on the track in a time grid.
In the Audio Track Editor, you can move and trim audio regions, split and join them, and edit them in other ways. You can scroll and zoom the Audio Track Editor, and zoom the amplitude of the waveforms in audio regions. Edits you make in the Audio Track Editor are non-destructive, so you can always return to your original recordings.
You can also quantize and edit the pitch of audio material in the Audio Track Editor using Flex Pitch. For more information, see Edit the pitch of audio in the Audio Track Editor or a zoomed in track.
You can also add audio effects to selected audio regions in the Audio Track Editor using selection-based processing. For more information, see Use selection-based processing with audio effects.
When Show Advanced Tools is selected in the Advanced preferences pane, you can edit the timing of audio material in the Audio Track Editor using Flex Time. For more information, see Flex Time and Pitch overview and Correct the timing of audio regions using Flex Pitch in the Audio Track Editor.
Do one of the following:
Select an audio track in the Tracks area, then click the Editors button 
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Select an audio track in the Tracks area, then choose View > Show Editor.
Double-click an audio region to open it in the Audio Track Editor.
The Audio Track Editor opens below the Tracks area. Along the top of the Audio Track Editor is a ruler showing time divisions, and a menu bar with local menus, tools, and other controls. The main area of the Audio Track Editor shows the audio waveform of the regions in the selected audio track.
Place the pointer in the bar at the top of the Audio Track Editor, and drag upward.
Drag downward to make the Audio Track Editor smaller again.
Drag the zoom slider in the Audio Track Editor menu bar left or right.
Click-hold the Waveform Zoom button in the Audio Track Editor menu bar, then drag the slider vertically to zoom the amplitude in or out.
Click the Editors button in the control bar.