Audacity is a free audio editing application that's available for Windows, Mac OS and Linux. It lets you record live audio, but you can also use it to record and convert old tapes or LPs to MP3 or other digital formats.
It's also easy to edit MP3, WAV, AIFF and Ogg Vorbis files: you can cut sections, amplify, remove noise and apply effects, such as fade-ins and fade-outs.
See also: How to convert audio tapes to CD or MP3
That makes it ideal for editing podcasts (it even supports auto duck) or making multi-track recordings. If you have the right hardware, it can even record multiple channels at once.
Here we'll show you how to get to grips with Audacity, including downloading extra codecs so you can save your edited audio files in MP3 format.
First, download Audacity from audacity.sourceforge.net and install it. We're using Windows 8 here, but you should be able to follow the tutorial if you’re using an older version, Mac OS or Linux.
How to edit audio files in Audacity
Start by opening an existing audio file. The easiest thing to do is to go to your Music folder and open an MP3 file. You'll see the blue waveform (two waveforms if it's a stereo track), a time scale along the top and playback controls.
Let's fade in this track because we don't want it to start loudly. The selection tool (the same icon as used in Microsoft Office) is on by default. Click and drag a selection from around the five second mark back to the start of the track. From the Effect menu, choose Fade In.
To save your edited track, click File then Export… Browse to a folder in which you want to save the file and edit or type a name for the saved file in the File name: box. Using the drop-down box, choose MP3 as the format. You'll then see an Edit Metadata window where you can enter or edit the track name, artist, album, year and so on.
Don't enter any information. Instead, click Ok and you'll see a message saying Audacity can't locate lame_enc.dll. Click the Download button and your browser should open with instructions on how to download and install the MP3 encoder.
Return to Audacity, click the Ok button, dismiss the error and repeat Step 3, this time entering or editing the metadata. This time, when you click Ok, the file will export correctly as Audacity will find the encoder this time.
If you have a microphone, you can record live audio. First, make sure your microphone is selected using the drop-down menu (you can change whether to record in stereo or mono using the other drop-down to the right). Click File, then New and click the round red record button.
If your recorded audio is too quiet (the waveform doesn't reach the top and bottom of the scale) you can amplify it. Press Ctrl-A to select it all, then choose Amplify from the Effect menu. The slider will be set to the maximum value possible without clipping, but you can override this using the checkbox.
Most audio recorded on a microphone will have some background hiss. To remove noise, first select a silent portion of your recording a few seconds long. It's easier if you first zoom in: click the magnifier and select a section. This will then fill the screen.
Switch back to the selection tool and highlight a couple of seconds of 'silence'. Now choose Noise Removal from the Effect menu. In the window that appears, click Get Noise Profile. Launch the Noise Removal tool again and click Preview to listen to the result. You can use the sliders to tweak the filtering.
You might want to change some default settings, so click Edit and then Preferences. Under devices you can choose which playback and recording devices to use. Click Quality and you can choose the default sample rate for recordings.
To set the default quality when exporting MP3 files, click File then Export. It's easy to miss the Options… button in the dialog box, but clicking it brings up another box where you can set the bitrate and whether it's constant or variable.