Basic Audio Editing
As a general rule of thumb, you should only import uncompressed audio into any sound editing program. This means you should import .wav, .aiff or another lossless file type. While it is technically possible to import compressed audio like mp3 files, you would likely see a decrease in quality as you recompress it on export.
Every time a file is compressed, it loses some quality -- similar to that of making a copy on a copy machine. Recompressing is analogous to making a copy of a copy.
To import audio, click on the File menu and select import --> Audio.
Once imported, you can use the space bar to play your audio file, or press the green play button at the top.
Using the Selection tool to edit audio
Use the selection tool to jump to various points in your track, or click and drag to select a portion of the track. If you move the cursor to the very edge of a selection, a small hand with a finger appears. This allows you to change the size of the current selection.
You can press the delete key on your keyboard to remove a highlighted portion of a track. Or you can use the standard copy, cut and paste key combination to move around segments of audio.
Whenever you remove a portion of the track, Audacity automatically slides the audio immediately after the selection to fill in the gap left. If you do not want this to happen, use Split Delete from the Edit menu instead.
When using Split Delete, a gap is left in the audio track which will be heard as silence.
Split Delete only works with highlighted portions of audio. If you wish to simply split a track in half without selecting it first, then use the Split option under the Edit menu.
You can use the time shift tool to move each piece throughout the track independently. Moving one block of audio to the other side of another segment is technically possible, but can be difficult to do. The first option is to simply drag it to the other side, but in order for it to work you must have enough room to accommodate the block on the other side. Also, you must be able to see the other side from the view. If you can't, you may need to zoom out.
The other option is to copy and paste the block using the selection tool.
Zooming in and out
Audacity offers several different methods for manipulating the viewable workspace. We'll start with the zoom tool.
Using the zoom tool, simply click on the track to expand it horizontally.
To zoom out, simply right-click on the track with the zoom tool, or hold down the shift key to change the zoom tool to a zoom out tool.
To zoom on the track vertically, you should click the front of the track where the amplitude measurements are displayed. But here's the trick: where you click on the ruler will determine which portion of the track will be magnified.
Clicking on the top of the ruler will zoom vertically on the top portion of the track.
If you click on the bottom of the ruler, you would zoom in on the bottom of the track.
To zoom out, follow the same steps as the horizontal zoom: either right-click on the ruler, or hold the shift key and click on the ruler.
(Note: Audacity makes it easy to zoom in vertically by allowing you to click on the ruler with any tool. The same effect will occur. You don't need to be on the zoom tool to cause it.)
Stretching the size of the track
You can easily change the size of the track itself by moving the mouse over the bottom edge of the track and dragging down.