An Introduction to
An open source cross-platform sound editing program
Although it may not have all the features of Adobe Soundbooth, Sony SoundForge, or Adobe Audition, it definitely has enough tools to do some decent sound clip editing for your web sites, video, or audio presentations.  Best thing of all is it's free, and if you've done any sound editing at all, you'll find it quite intuitive.

Download Audacity from http://audacity.sourceforge.net/ for Mac, PC, or Linux.

This tutorial goes through various steps to extract a bass solo from a sound clip. You can use any mp3 file to follow along with this tutorial.



This is a mono (single channel) 1 minute and 20 second sound clip in a .wav file format.  To open a sound file got to File --> Open.

If you haven't read my Physics of Sound tutorial yet, click here to see it.

Audacity works with a variety of common sound file formats, (.wav, .au, .aif, .mp3, .ogg, .lof, and Audacity's native file format, .aup).

Fig. 1

 

This is a stereo (two channel) mp3 file of the same song.  The Left channel is shown at the top and the Right channel is shown at the bottom.

To follow along with this tutorial open any mp3 file that you have on your computer.

Fig. 2

 

The playback controls are pretty standard.

Fig. 4

 

Fig. 3

Click the green button to Play. You will see the audio levels in the Meter Toolbar, (volume level of each track). You can adjust the volume and the left/right balance with the Gain and Pan sliders on the left. This does not change the actual volume of the file, it just changes the playback as you are listening to it.  You can adjust these file characteristics, but we will cover that later.

Click here to listen to this sound clip.

Let's say that I wanted to select a specific part of a song, (in this case, it's my bass solo). I'm not an egotist, it's just that I need some sort of example to use for a project.

All I have to do is select the I-beam tool, and drag over the part of the song that I want to select...

Fig. 5

 

Select a section of your mp3 file. With the section selected, go to Edit --> Copy. This will place the selection in the clipboard.

 

Fig. 6

 

Go to File --> New to start a new empty file, the go to Edit --> Paste, to paste the new clip into the file. The pasted clip will automatically fill the entire width of the timeline, but it is actually shorter than the original file.  You will be able to see a significant difference in the look of the wave patterns.  Click here to listen the the new clip. 

I have my bass solo, but there is a bit extra at the beginning and at the end that I will cut out in the following steps.

Fig. 7

 

To get a good look at the part of the sound wave that I want to eliminate I will zoom in on the region. Go to View --> Zoom In, (Ctrl + 1 on a PC). You might need to zoom in a few times. Zooming in has the effect of stretching out the timeline. Any given period of time will appear wider so you will be able to see the actual sound wave pattern more clearly.

Fig. 8

 

Having zoomed in, I can clearly see the exact spot of the beginning of my bass solo. Using the I-beam Tool again I drag over the selection that I want to remove.

If you are not sure that you have the right selection you can hit the Play button with the selection still highlighted, and Audacity will play only the highlighted selection.  To test you can either highlight the part that you want to cut, or the part that you want to keep, and Audacity will play that particular selection. Make a note of the exact transition spot so you know where to cut.

If you are satisfied that you have the correct selection highlighted go to Edit --> Cut to remove the unwanted selection.

Fig. 9

 

An alternative to deleting the unwanted selection is to 'generate silence'. If you don't want to start a sound clip abruptly, but would rather have a 'lead-in' time, you can change the volume of the selection to zero. Go to Generate --> Silence. Notice the flat shape of the sound wave at the beginning of the clip, indicating Silence.

Fig. 10

 

If you listened to the clip in a few steps ago, you would have noticed a bit of vocals at the end of my bass solo.  I can use the same procedure to eliminate the unwanted vocals, but this time I am going to do a little more editing.

In reality, there is a bit of overlap between the end of the bass solo and the start of the vocals. Cutting at the vocals will result in an abrupt sounding end to the bass solo. Click here to see what I mean.

Fig. 11

 

The bass solo ends on a sustained note that fades out. Unfortunately, the fade is overpowered by the vocals, but I am going to 'rebuild' it through the magic of digital sound editing.

Fig. 12 shows a Zoomed-in view of the last note of the bass solo. The sound wave shape is quite visible. 

Fig. 12

 

This is a zoomed-in view of the last few seconds of the sound clip. I have selected 3 wave cycles that look visibly similar. I copied and pasted these 3 wave forms several times in order to extend the last note of the bass solo. It was very important to copy and paste at the exact right spot so that the timing of the waves remain consistant.

Fig. 13

 

Once I sufficiently lengthened the sustained last note I applied a Fade Out effect to the last second or so of the sound clip.  To fade out, select the last part of the sound clip and go to Effect --> Fade Out.

Fig. 14

 

Fig. 15 is a look at the finished clip. To get a nice 'fade-out' effect you can repeat the effect two or three times, each time making a slightly longer selection.

The image above  shows a nice, smooth fade-out effect.  Click here to hear the finished clip.

Fig. 15

 
   
2008 T. Carson