Loudness Gain Adjustments
The Timeline View also let users make loudness gain adjustments by simply adding/adjusting loudness handles.

Adding Loudness Handles
To add loudness handles simply go the position in the waveform and press "Ctrl+LeftMouseClick" on the line right above waveform.
Dragging the loudness handle also shows loudness value in the tooltip.

Removing Loudness Handles
Simple press Ctrl+double click on the handles to remove them.