Audacity is an open source audio editing program that is available for free on the OS X and Windows. This tutorial takes you through basic audio editing. That means modifying a sound that has already been recorded. Audacity also allows you to record your own audio as well. Recording is not covered in this tutorial.
Below is the Audacity interface.
Open an audio file
In class there will be files available for you to download. If they are zipped, make sure to extract them before opening in Audacity.
Choose Import Method
When you're importing a .wav or other uncompressed file it will ask you whether you want to copy the file or work from the original. Working from the original will not overwrite your file but it does mean that you have to keep that file in that place or else the next time you open your Audacity Project the file will be missing and it won't work.
If you're only working with one file then copying can be safer. If you have a large number of files it's better to use the Read Directly method. In this case keep the original files in a folder by your project so you won't lose them.
The copy method will be used here.
Save your Project
In much the same way Photoshop has the .psd file format we use when editing a photo and then save it to different formats for the web page, Audacity has an .aup project file format we use to save what we are editing on. We will later export our tracks for listening on the web or in a player.
Click File>Save Project
Choose where to save your project
If you're working with sound files it's best to save it close to them.
Waveform View of Impoted Audio
When you import your audio you should see a waveform view of it. In this case a stereo file was imported so you see two wave forms, one for the left and one for the right channel (1)
The display of both channels together is called TRACK. You can also see the track settings on the left side of the track. Right now this file is set to Stereo (2), 44,100Hz Sampling Rate (3) and 32bit sample size (4).
Changing the Bit Depth (called Sample Format in Audacity)
You can click on the triangle (1) by the track name and change the bit depth (2).
Changing the Sampling Rte
You can also click on the same triangle (1) and change the sampling rate (2)
The gain is the relative volume of this track to other tracks (more on creating them later). Generally you don't want to mess with this unless you have more than one track and want to make one louder or quieter relative to the others.
By changing the panning you change how loud stereo tracks are relative to each other. Again, you usually only do this if you have a specific reason to do it.
Clicking on View > Toolbars allows you to control which ones are showing. For now we will show all of them.
These controls allow you to play (1), pause(2), stop(3), move to the beginning(4), move to the end(5) and record audio(6).
A Note on Pausing
If you've paused playback (the button will be grey like below  ), then you can't do many of the editing things we will cover in the next steps. Click the stop  button and then you will be able to do the editing.
Select a section of your file by
- clicking on the Selection Tool
- clicking and dragging over the waveform representation in the track.
To delete this section, simply hit the delete key.
If you choose an effect it will now only be applied to the seleced audio.
Click the Zoom Tool  magnifying glass icon.
Your cursor will turn into the magnifying glass.
Then you can click on a part of the waveform to zoom in on 
If you hold the shift key down the plus inside the magnifying glass will turn to a minus and you can zoom out.
Alternative Zoom Tools
You can use these buttons to Zoom In, Zoom Out, Fit Selection to viewing window and Fit Project to the viewing window.
Changing a Selection
With the Section Tool enabled  you can change your selection by putting your cursor at the edge of the selection until it turns into a finger,
or by holding the shift keydown and clicking and dragging
I find it easier to visually see where a piece of audio starts or stops in a relatively Zoomed out view. You can first set your selection that way. Then choose the zoom tool and click on the edge  of where you selected to zoom in there and be able to make finer edits
Selection Tip Continued
When setting the end points you want to zoom in to a level more like this so you can see where the waveform is crossing the 0 mark (horizontal line in the middle).
Proper Selection End Points
When choosing exactly when to start and stop your selection it is best if you do it at a point when the waveform is crossing the middle horizontal line .
This prevents pops and clicks when playing back your selection and if you are editing pieces together.
One way is to first zoom in and then move your selection to a point that is close.
Use the Find Zero Crossings Tool
Select the find zero crossings and audacity will move the selection to the closest crossing.e
Using the selection view
You can also see the precise start, end and lengths of your selection with this window (usually at the bottom of the screen). Click on the End or Length buttons to determine what the second number is showing.
You can click on these numbers and edit them.
Changing the selection display units
You can change how precise the units displayed are. We will try hundreths of a second here. Depending on what you're working with (like video, film etc) you can choose others.
Zoom back out
After you're done setting zero crossings or doing up close editing, click the Fit Project button to zoom back out.
Duplicate a Selection
This takes what you've selected and duplicates it on another track.
Muting and Soloing
This shows after a section has been duplicated. To hear the new track by itslef the mute  has been clicked on the original track. Now you will not hear that track.
Solo  is another method and does the opposite, just plays only the track that is soloed.
To add an effect, first make a selection.
Then choose your effect from the Effect menu 
There are too many to cover here. We will try some out in class.
To play the audio on the web or in a music player we will need to export it.
Choose File > Export
Select the File format you want
On the web we will need both Ogg Vorbis and MP3, so we will have to export it twice.
Specify MP3 Options
You can click the Options button and change how exactly the file is exported.
If you want some file formats allow you to enter meta data about the file. If you enter any , be accurate.
If you have more than 1 stereo track then most likey your files will need to be mixed down to one track. This just lets you know that is happening.
For audacity to export the MP3 format you need a special plugin. If you don't have it, then you can't export MP3.