Audacity: The Free Dimensional Sound Editor, Part Two
Learn how to mix sound and voice to create professional and audacious effects for your next audio project.
Thursday, March 10th, 2011
Once you’ve sucessfully inserted the 16 seconds of silence into your file, you need to lower the volume of the music track so that the voice-over can be heard over the music. Select the portion of the music track that corresponds to the voice-over to the end of the recording. Select Effect->Amplify, enter -6.0 into the Amplification (dB) field to lower the volume significantly. See Figure 6. Repeat the amplify process to lower the music more, if necessary, but do so incrementally so that you can check the results at each stage of the process.
Figure 6: Lowering the Loudness of the Music Track
For further enhancement and a more professional sound, select the portion of the music track that follows the voice-over, select Effect->Fade Out to fade the music to silence as shown in Figure 7. Fading out the music creates a better transition to the next portion of the recording than ending the music abruptly.
Figure 7: Using the Fade Out Effect on the Music Track
Once you have your tracks situated like you want them, you’ll want to save them as a single file. Do this by exporting the workspace (File->Export) out to a file type (MP3, Ogg Vorbis, WAV) for your audience or as recognized by your external application.
Audacity is powerful but simple in its design, which makes it a versatile and elegant application for sound mixing, editing, and manipulation. Such applications can be intimidating for the first-time user but Audacity is readily usable by anyone who’s ever used a VCR, DVD, or any music-related gadget. You’ll find that you can be productive with Audacity after a few short interactive sessions. No lengthy or expensive training required. Audacity is fun, free, and ready to go to work. Enjoy.
If you’re looking for a more thorough treatment of Audacity, check out the online documentation or the new The Book of Audacity from No Starch Press.
Kenneth Hess is a Linux evangelist and freelance technical writer on a variety of open source topics including Linux, SQL, databases, and web services. Ken can be reached via his website at
http://www.kenhess.com. Practical Virtualization Solutions by Kenneth Hess and Amy Newman is available now.
Comments on "Audacity: The Free Dimensional Sound Editor, Part Two"
Re- lowering the volume in the voice over section of the music.
The procedure you’ve outlined will produce a step function in the music track where the volume drops and goes back up again. This will be audible as a click, the severity of which will be directly related to the difference in level. A smoother method is to select the section of music and duplicate it (ctrl-d). Select the duplicate section and invert it. Fade the beginning in and the end out. Reduce the level of the duplicate to produce the amount of volume reduction that you want. Since the duplicate track is inverted, it sums with the original to lower the volume. One advantage of this method is that it doesn’t modify the original track so the file can be saved and the changes undone at a later date. I combine the two tracks before outputting a wav file, but don’t save that change.
I’ve never heard a click. This method creates a smooth sound. If yours is making a click, I’d check the hardware.
Oops.
I’ve never heard a click, but that’s because I’ve never done what you’ve suggested. I’m not speaking from experience, but from the point of view of the physics. Introducing a step function in the volume level in effect produces a square wave, whose magnitude is equal to the difference in volume. The laws of physics dictate that you will produce a sound that wasn’t in the original program. It may be masked by the voice over, but it’s there just the same. Zoom in on the music at the start or end point of the volume shift and you’ll see a vertical line.
I use Audacity frequently and I haven’t noticed the click.
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