RE:Como hago para agregar sonido ?
creo que no, 3dmax solo admite sonido en formato WAV.
a ver si te sirve este tutorial
To add a sound file to your animation, you use the Track View dialog box.
RightClick the camera viewport name to open the viewport dialog box.
Choose Swap Layouts to change the top and front viewports to track view.
Click the word Sound near the top of the hierarchy list to highlight it.
RightClick on the highlighted word and choose Properties from the track options dialog box. The Sound Options dialog box opens.
Click the Choose Sound button. This lets you choose a sound file from your computer system.
Choose the sound file which may be a .wav or the sound portion of a .avi file. This allocates the sound to the sound track in the track view panel.
OK the Sound Options dialog box.
Click the + sign in the small circle on the left of the green cone in the sound track line. The sound file shows in the wave form track.
The track view display replaces the top and front viewports. If you cannot see all of the sound file in this view, you can open an independent re-sizable track view by choosing Track View from the edit pull down menu.
Click and drag the white box at the left end of the black line at the top of the track view to determine the relative position of the sound track. The two white boxes show the start and the end of the sound. You can not adjust the sound itself, but you can determine when it begins to play.