PowerPoint users always want to add audio to their presentations
- either as voiceover sounds or background music tracks. However,
since PowerPoint offers no native sound fades, most of these tracks
need to be faded using a sound editing application.
For this tutorial, I am using Sony
Sound Forge on Windows XP Professional, but the same techniques
should work with earlier versions of Sound Forge. In most cases,
other sound editors work in the same way.
- Launch Sound Forge and open your digital sound or music file
(WAV, MP3, CDA, WMA, ASF, etc.). Play your file to get an idea
of how it sounds.
Figure 1: The Sound Forge interface is easy to understand - in
this screenshot, you can see how a sound file is displayed. Since I have
opened a stereo file, you find two sound waves (data) shown representing
the left and right stereo channels. Each channel can be edited independent
of each other as well as together.
- Your file will be represented as sound waves (two of them if
you open a stereo sound file) - as you can see in Figure 1,
the sound waves taper into oblivion towards the right. This means
the sound already has a fade-out (de-crescendo) processed. Select
the entire sound file by pressing Ctrl + A or select part of
the beginning.(see Figure 2).
Figure 2: The sound waves color change to show that
the displayed sound is selected. You can also select the entire
sound (left) using Ctrl + A; or part of the sound wave (right)
by dragging over a part of the display.
- Now choose Process | Fade | In. Sound Forge will create a fade-in
(crescendo) effect - see Figure 3. Play again to ensure
that you are satisfied with the effect - otherwise Undo (Ctrl
+ Z) and try again after choosing more or less of the beginning
area.
Figure 3: You'll notice a distinctive fade-in within
the sound wave display - compare this with the waves in Figure
2 when the fade-ins were not applied.
- Save your sound file to a file format - Sound Forge allows
you to save as MP3, WAV and WMA - PowerPoint can accept these
formats through its Insert options. However, if you need to add
a transition sound in PowerPoint, you can only use the WAV format.
- Use the same techniques to add fade-out effects - just substitute
the actual process command to Process | Fade | Out. Save again
to your chosen format.
Sound Forge allows much more control over fades if you use the
Process | Fade | Graphic... option.
In addition to the Fade option, Sound Forge's Process menu contains
several effects you might want to experiment with (see Figure
4).
Figure 4: The Process menu allows to you do much more
than fades.
