You can record keyframes for audio level and pan by clicking the Record button, then
adjusting the dials or sliders in the Audio list, the HUD, or the Inspector. Alternatively,
you can manually add a keyframe to the Level and Pan parameters in the Audio Track
Inspector (any subsequent adjustments add a keyframe at the current playhead position).
Recording keyframes for audio level and pan can be useful for trying out changes and
hearing the results in real time.