Continuing from last week’s introduction to Audacity, this week you’ll take a deeper dive into some of Audacity’s advanced editing features by learning how to create a professional sounding introduction for your audio projects. These are the exact techniques I used to create the introduction music and voice-over for the Frugal Tech Show podcasts.
This article focuses on Audacity 1.3.12 Beta on Ubuntu Linux 10.10 and uses a Logitech 350 USB Headset with built-in microphone. I selected two audio files for this project: A 30 second music clip and an 11 second voice-over clip. Mixed together with a little advanced Audacity magic creates a studio-quality introduction that costs nothing and only takes about 30 minutes to perform.
The Setup
To mix two files together into a single usable sound byte, either you have to record multiple tracks into Audacity directly or to open pre-existing files and work with them. We’ll be working with the latter scenario for this demonstration.
To create a single file that mixes voice and music, open Audacity, select File->Open, search for your file, select the file, click the Open button and the sound file is read into the Audacity editor. Add the second file into the editor by selecting File->Import->Audio, search for your file, select the file, and click the Open button.
Both files are now in the editor. See Figure 1. The upper track is the sound file, the lower is the voice-over file. Although, the order of the files in the editor doesn’t matter. Note that both files load at position 0 in the editor window.
Figure 1: Music Track and Voice-over Track Loaded into Audacity
Insert Silence
To create the intro music to voice over transition, add silence to the voice-over track. Since we want to play intro music, then add the voice-over, then finish off with a second or two music, add 16 seconds of silence.
Click your mouse into a silent region, if one exists, or at the beginning of the voice-over track, select Generate->Silence, enter 16 (seconds) into the Silence Generator dialog that appears. See Figure 2.
Figure 2: Audacity’s Silence Generator
Figure 3 shows the result of the 16 second silence insertion.
Figure 3: Sixteen Seconds of Silence Added to Voice-over Track
You might find that your tracks are linked and when you insert silence into the voice-over, both tracks move 16 seconds to the right, which is not the desired results. See Figure 4 for an illustration of this.
Figure 4: Sixteen Seconds of Silence Added to Linked Voice-over Track
Note the “Chain-link” symbol in the upper track and that 16 seconds of silence was inserted into both tracks. To remove this anomaly, select Edit->Undo Silence. To unlink the two tracks, select the Link Tracks icon to unlink the two tracks as shown in Figure 5.
Comments on "Audacity: The Free Dimensional Sound Editor, Part Two"
tchilco
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.
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.
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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.
I just like the valuable information you supply in your articles. I’ll bookmark your blog and check again right here frequently. I am relatively certain I will be informed lots of new stuff proper right here! Good luck for the next!