The objective of this tutorial is to learn how to edit a sound file. To achieve this objective, we are going to open an existing sound file, remove all but 10 seconds of this file, apply a 1-second fade-out at the end, export the results, and play it in your favorite audio player. These steps will introduce the basic steps commonly used when editing a file.
Step 1: Find a file to edit
Audacity can open many common audio file formats, including WAV, AIFF, and MP3. If the optional FFmpeg library is installed, a larger range of formats, including WMA and the audio content of most video files, can be opened. Audacity cannot open copy-protected music files.
If you want to edit music that you have on an audio CD, you need to “rip” the music into an audio file. See the Audio CDs page for information on getting the audio off of CDs and into Audacity.
Don’t have any audio files handy? There’s lots of free music online! Here’s one site where you can download free music: Opsound
The recordings on this site are free, distributed under the Creative Commons Attribution-Sharealike license, which gives you the right to create a derivative work without paying royalties, as long as you give credit and make your derivative work free, too. This is similar to the license for Audacity, which allows any programmer to modify it and redistribute it for free.
Step 2: Open the file with Audacity
Open Audacity. To open an audio file, you can select “Open” from the “File” menu, but a handy shortcut is to just drag and drop the file into Audacity:
|Windows: Drag the audio file icon
into the open Audacity window.
|Mac: Drag the audio file icon
to the Audacity icon in the Dock.
Linux users: you can also run Audacity on the command line and give the name of the file to open as a command-line argument.
Step 3: Look at the waveform
This image shows a stereo waveform. The left channel is displayed in the top half of the track, and the right channel on the bottom. When the waveform is “larger”, the audio is louder, and vice versa.
The ruler above the waveform shows you the length of the audio in minutes and seconds.
Removing any DC offset (if present)
DC offset can occur in audio files so that the recorded waveform is not centered on the horizontal line at 0.0 amplitude. The example above is centered on 0 correctly and carries no DC offset. It can be caused by recording with a faulty sound card. If this is the case with your recording use the Normalize effect to remove any DC offset. Put a check mark in “Remove any DC offset…” but leave “Normalize maximum amplitude…” unchecked.
Step 4: Listen to the audio file
The image above show the Transport Toolbar. The functions of the buttons are (from left to right): Skip to Start, Play, Record, Pause, Stop and Skip to End.
Click the Play button to listen to the audio. Click the Stop button to stop playback. If you don’t hear anything, see Audacity Setup and Configuration.
You can use Space on the keyboard as a shortcut for Play and Stop.
Click on the selection tool , then click on the waveform to choose a place to start, then click the Play button. Click and drag to create a selection, and then when you click Play, only the selection will play.
You can also select audio entirely using the keyboard. For example you can use the left-arrow and right-arrow keys to move the cursor left and right in the waveform. Holding down the shift key while pressing the arrow keys will create and extend a selection. Holding down the shift and control (CTRL) keys while pressing the arrow keys will contract an existing selection.
Clicking the Skip to Start button or pressing the Home key the will move the cursor to the beginning of the track. It’s kind of like rewind, but it’s not for playback – it will only work when playback is stopped.
Similarly, clicking the Skip to End button or pressing the End key the will move the cursor to the end of the track.
You can use the keyboard to skip around the audio file while listening. For example:
- Press left-arrow to move the playback cursor back one second
- Press right-arrow to move the playback cursor forward one second
- Press SHIFT + left-arrow to move the playback cursor back 15 seconds
- Press SHIFT + right-arrow to move the playback cursor forward 15 seconds
The amount the cursor moves in this situation is called the “seek time”. The long and short seek times (one second and 15 seconds in the examples above) can be set in the Seek Time When Playing section of Playback Preferences.
Step 5: Create a 10-second clip from your audio
You edit audio waveforms in Audacity in much the same way as you would edit text in a word-processing document. When you are editing text you first select the text you want to change and then choose what you want to do with it. You might want to cut or copy the text, delete it, paste new text in it’s place, or change it to bold. You do the same thing in Audacity: first zoom and select the range of audio you want to change, and then choose what you want to do with it.
The image above shows the Edit Toolbar with the Zoom buttons highlighted. This is the Zoom In tool, and this is the Zoom Out tool.
To zoom in to get a closer look at the waveform, first choose the Selection Tool , then click near the point you’re interested in, then click the Zoom In button. Keep clicking the Zoom In button until you see the detail you need. Note that when you click the Zoom In button the cursor is centered on the screen.
There are also menu commands and keyboard shortcuts for zooming. View > Zoom In (or CTRL + 1) is the same as clicking the Zoom In button. View > Zoom Out (or CTRL + 3) is the same as clicking the Zoom Out button. View > Fit in Window (or CTRL + F) will zoom the waveform so it fits in the window.
Use the Zoom commands so that you can make maximal use of your Audacity window to see as much detail as you need, or to make sure you see the entire file when necessary.
Walk through deleting all but approximately 10 seconds of selected audio
To cut this audio file down to 10 seconds, follow these steps:
1. Click near the point where you want the 10-second piece to begin.
2. Zoom in until the Timeline shows 10 seconds or more before and after the cursor.
3. While holding down the shift key, click 10 seconds to the right of the cursor.
- Note that this is just like selecting a range of text in a word processor
4. Press Space to listen to the entire selection. Playback will stop when the end of the selection is reached.
5. Adjust the start and end of the selection with the mouse:
- 5.1 Move the pointer over the start of the selection – the cursor will change to a left-pointing hand
- 5.2 Click and drag to adjust the beginning of the selection
- 5.3 You can adjust the end of the selection in a similar manner.
6. Press Space to listen to the adjusted selection. You don’t have to listen to all of it; press Space again at any time to stop playback.
- A convenient way to listen to only the adjusted start of the selection is to move the mouse pointer a little after the start of the selection then press B. The selection plays from the start of the selection to the pointer. To hear the adjusted end of the selection, move the pointer close to the selection end, then press B to play from the pointer to the selection end.
- You can also play a length of audio either side of the selection by pressing C. This lets you make sure there is no audio you want to keep that will be removed. Playing either side of the selection would also be useful if you later wanted to cuta small piece out of that selection – you would select the small piece to be cut, then could preview how the audio would sound after the cut. To adjust the length of audio played before and after the selection, go to Cut Preview in the Playback Preferences.
Optional – try adjusting the start and end of the selection with the keyboard
- Pressing SHIFT + Left-arrow will expand the selection to the left
- Pressing SHIFT + Right-arrow will expand the selection to the right
- Pressing SHIFT + CTRL + Left-arrow will contract the selection from the right
- Pressing SHIFT + CTRL + Right-arrow will contract the selection from the left
- Optional – try adjusting the start and end of the selection using the Selection Toolbar
- Click the “Length” radio button above the second group of numbers in the Selection Toolbar if it is not already selected
- Click on the first digit to the right of the decimal point in the Length box
- Press the 0 (zero) key – the digit changes to zero, the digit to the right is selected and the selection in the waveform changes to match
- Press the 0 key – the selection length is now 10.00 seconds.
You’ve now selected the portion of the audio that you want to keep. Make sure you have pressed Space to stop if the track is still playing, then to delete everything except the selected audio, click on Edit > Remove Audio > Trim.
If you make a mistake, you can always click on Edit > Undo. Audacity has unlimited Undo and Redo. You can undo your editing actions all the way back to when you opened the file. You can also Redo actions that you have undone.
You now have a region of audio that starts several seconds (or perhaps minutes) from the beginning of the track. You could move the audio to the beginning of the track, using Tracks > Align Tracks > Align with Zero, but this isn’t a necessary step because when exporting, Audacity will ignore the white space between time zero and the start of the audio.
Step 6: Fade out the last second
- Click the Skip to End button .
- Zoom In until you can see the last two or three seconds of the waveform.
- Click in the waveform about 1 second before the end.
- Click on Edit > Select > Cursor to Track End.
- Click on Effect > Fade Out. The last second of the audio is smoothly faded out.
Note that we always select some audio first, then choose what action we want to perform on it.
Step 7: Export the resulting file
When you save an Audacity project with File > Save you are doing just that – saving an Audacity project. Audacity projects can be opened only by Audacity. If you want other programs (such as iTunes or Windows Media Player) to be able to open this file we need to export it.
Before we export this 10 second clip to a separate file we’re going to simplify things a bit. Go to the Import / Export Preferences, and under When exporting tracks to an audio file uncheck “Show Metadata Editor prior to export step“. Metadata Editor adds extra information about the speech or music into the file – see For More Information below to learn more. You can go back to the Import / Export Preferences at any time to re-enable Metadata Editor.
Exporting a WAV file
- Click on File > Export – the standard “Save” dialog for your operating system appears.
- Give the file a different name. Audacity always suggests a name for the file that is the same as the name of your Audacity project. It is always best to alter this so you don’t confuse your exported file with your Audacity project.
- Choose a location to save the file in the usual manner.
- At the bottom of the Save dialog is a drop-down menu labeled “Format“. From this menu choose “WAV (Microsoft) signed 16-bit PCM”.
- There are no options for the WAV file format, so there is no need to click the “Options” button.
- Click the “Save” button to complete the export of your project to a WAV file.
Exporting an MP3 file
In order to export files from Audacity in MP3 format you will need to download and install the optional LAME MP3 encoder. Instructions are here . Once you have downloaded and installed the LAME encoder you will be able to create MP3 files using Audacity.
The steps for exporting a file in MP3 format are the same as for a WAV file, except:
- In the Save dialog, from the “Format” menu, choose “MP3 files”
- Then click the “Options…” button to set the bit rate and other options for the MP3 file.
Step 8 – Testing your new Audio Production
To demonstrate the difference between an Audacity project (the AUP) file, and a sound file you export from an Audacity project:
- Click on File > Close, saving changes if asked.
- Find the AUP file on your computer and attempt to open it with the audio player of your choice (e.g. iTunes, Windows Media Player). You can’t.
- Find the exported WAV file on your computer and attempt to open it with the audio player of your choice. Success!
You can’t open an Audacity project in a media player. Only by exporting your project can you listen to it in a media player.
Once you’ve exported your project you should keep the original project file (AUP) and its associated _data folder around in case you want to make some changes to it in the future.