From the mouth of Adobe...
Audio Mixer automation modes
Automation modes are set in the menu at the top of each track. For example, drag a track’s volume fader or pan control during playback. When you replay the audio with the track’s automation menu set to Read, Touch, or Latch, Premiere Pro plays back the track with the adjustments you made. As you make adjustments in channels of the Audio Mixer, Premiere Pro applies the changes to their respective tracks by creating track keyframes in a Timeline panel. Conversely, audio track keyframes you add or edit in a Timeline panel set values (such as fader positions) in the Audio Mixer.
For each audio track, the selection in the automation options menu determines the track’s automation state during the mixing process:
- Ignores the track’s stored settings during playback. Off allows real-time use of Audio Mixer controls without interference from existing keyframes. However, changes to the audio track aren’t recorded in Off mode.
- Reads the track’s keyframes and uses them to control the track during playback. If a track has no keyframes, adjusting a track option (such as volume) affects the entire track uniformly. If you adjust an option for a track that’s set to Read automation, the option returns to its former value (before the current automated changes were recorded) when you stop adjusting it. The rate of return is determined by the Automatch Time preference.
- Records adjustments you make to any automatable track settings that aren’t set to Safe During Write, and creates corresponding track keyframes in a Timeline panel. Write mode writes automation as soon as playback starts without waiting for a setting to change. You can modify this behavior by choosing the Switch To Touch After Write command from the Audio Mixer menu. After playback stops or a playback loop cycle is completed, the Switch To Touch After Write command switches all Write mode tracks to Touch mode.
- Identical to Write, except that automation doesn’t start until you begin adjusting a property. The initial property settings are from the previous adjustment.
- Identical to Write, except that automation doesn’t start until you begin adjusting a property. When you stop adjusting a property, its option settings return to their previous state before the current automated changes were recorded. The rate of return is determined by the Automatch Time audio preference.
- http://help.adobe.com/en_US/premierepro/cs/using/WS1c9bc5c2e465a58a91cf0b1038518aef7-7f0ca .html
Gentleman, thanks for your help, but I'm sincerous... I still cannot see any difference between touch and latch. Would you mind explain this again with your own words?