Understanding nonlinear volume changes

A rubberband segment between any two adjacent handles in the Timeline is linear; each handle is connected to the next handle by a straight line. Volume adjustments you make using the Audio Mixer window can be linear or nonlinear, depending on the rate at which you drag a volume fader. Although linear volume changes provide a quick and simple way to change volume, they do not always sound natural to the human ear. Sounds derived from physical objects, such as a bell, fade away at a nonlinear rate. You can approximate a nonlinear volume change in the Timeline by positioning volume rubberband handles along a curve.

Selecting the Logarithmic Audio Fades option in the Audio Settings portion of the Project Settings dialog box (see Audio settings) converts linear volume changes to logarithmic volume changes when you play or preview the project. Likewise, selecting the Logarithmic Audio Fades option in the Audio Settings portion of the Export Movie Settings dialog box (see Exporting a video) converts linear volume changes into logarithmic volume changes in an exported movie. When you select this option, the linear volume changes you create in the Timeline are still linear in the project; only the output changes.

Mixing Audio > Understanding nonlinear volume changes