The Sound track lets you add audio to your animations by either of two options: Default Sound (Sound Options dialog) and ProSound.
To assign the sound option, use Preferences 
Animation Sound Plug-In. To access the sound settings, open Track View, click and then right-click the Sound track, and choose Properties.
While Default Sound is easier to use, ProSound is far more powerful and offers more options.
ProSound is a real-time, multitrack audio solution for 3ds Max that includes full support for and integration with Track View. For best results, use Track View in Dope Sheet mode.
When using the Default Sound plug-in, the Sound track in the Track View Controller window provides two sound options: You can use the metronome to generate a series of beeps, or load a sound file to play back.
