Ok, now I think I understand better - it´s not different layers you are “selecting” but an area inside the spectral editor, in the same layer and the same audio file.
I tried this out, and as you noted it´s only the selected area that actually plays any sound - even though the playhead is started outside of the selection. I think the option to listen outside the selected area is a good Feature Request for future updates!
If you want to listen to a file, make a change in a certain area and listen to the file again you need to Deselect before you can hear the whole file.
But if you want to alter the change you made you can user Reselect to select the same area again to make more adjustments.
The selection is kept in memory until you make a new selection, so if you´re only changing the gain it´s advisable to set up key commands for the operations to minimize the risk of accidently making a new selection and loosing the one you are working on.
If you need to come back to the same area again, or just want to be sure not to loose the selection you just made, you can Save the selection. It is actually saving the audio and the time stamp, and when Loading your saved selection it will also redo the selection!
So, in short:
- Set up a key command in Edit - Preferences - Shortcuts for Process>Amplitude>Gain, let´s say [Shift+G]
- Listen to your audio file and make your selection where you want to change gain, using the selection tool. For extra safety, change from the Selection Tool to the Playback Tool after this - this will avoid the risk of making a new selection somewhere when you work on the file, and it also makes it easier to listen back.
- Use your key command to bring up the gain changing dialog ([Shift+G] if that was your choice) and do your change + press “OK”
- Deselect the area [CTRL+D]
- Listen again with [Spacebar], or doubleclick in the ruler at the point where you want to start listening - or use the Playback Tool if you have it selected, or by holding [CTRL] and click-hold in the spectrum editor where you want the playback to start.
- Reselect [Shift+CTRL+D] and [Shift+G] to fine trim your gain change
- Do steps 4 -> 6 until you are happy with the result, and if you need to go back to the same selection later you can Save it (“Select - Save Selection”, or make your own key command for a shortcut)
- Go back to step 2 again and make your next edit
If something goes wrong you can always Undo [CTRL+Z] / Redo [CTRL+Y] your steps in the history. If you are working in Pro the number of undos can be changed by the user (max 64), but in Element and One it´s max 8.
Now, I think Spectralayers big advantage is making use of the layers, so if it´s only one file you are working on there is also another way, that may be much easier:
- Make your selection
- “Edit - Cut Special - Cut to new Layer” or [CTRL+Shift+X]
- Change gain with the volume handle in your new layer
- Listen back and adjust the volume
- “Layers - Merge All” when you are done if you want to merge the layers into one file again.
Hope this solves your issue, and you could mark your post as a Feature Request to alert the developers!