Audacity is a program that manipulates digital audio waveforms. In addition to recording sounds directly from within the program, it imports many sound file formats, including WAV, AIFF, and MP3. PCM formats of 8, 16, 24 and 32-bits can be imported and exported.
Interface and Settings
When you open audacity your workspace will be empty except for the toolbars at the top of the window.
The Playback toolbar is similar to any other recording or playback device; containing Pause, Play, Stop, Skip, Skip back and Record buttons.
Beside the playback controls are other primary tools.
The Selection Tool is used to select audio. You can click in a track to position the cursor to play from, or click and drag to select a range of audio.
The Envelope Tool gives you detailed control over how tracks fade in and out, right in the main track window. When the envelope tool is selected, the amplitude envelope of each track is highlighted in a green line, with control points at the beginning and end of each track. To change a control point, click it and drag it to a new position. To add a new point, click anywhere in the track where there is not already a control point. To remove a point, click on it and drag it outside of the track until it disappears, then release.
The Time Shift Tool allows you to change the relative positioning of tracks relative to one another in time. To use this tool, simply click in a track and drag it to the left or right. To align two tracks together or reset their time shift back to zero, use the Align Tracks Together or Align with Zero commands.
The Zoom Tool allows you to zoom in or out of a specific part of the audio.
The Draw Tool enables you to draw in to the actual waveforms. This is especially useful to eliminate small pops and clicks from material. For instance ALT + click smoothes a area of audio.
The editing tool bar enables you to do basic editing to your file such as: Cut, Copy, Paste, Trim (Delete) and Silence. There are also buttons to undo and redo your changes to your project as well as a variety of zoom options to better edit your project.
The mixer tool bar contains your input and output controls. The left hand slider with the volume symbol lets you control the output level of your soundcard while the right hand slider with the microphone symbol controls the input level or recording level setting of the soundcard driver.
The drop-down menu beside the input level shows you the options you have for the input device (often a microphone) for recording and the output device for playback. The default soundcard is usually already detected and selected by the program. In terms of recording options if stereo is checked, the recordings you make in Audacity will be in stereo, otherwise they will be monaural. Note that the interpretation of mono recordings depends on your system either two channels will be mixed or it could give you just one channel.
Although the toolbars indicated above are always present note that their positions can be changed around.
There are keyboard command functions for every tool but the most important ones are Spacebar to play, R to Record, CTRL X to Cut, CTRL C to Copy, CTRL V to paste, CTRL S to save.
The default settings for every track will be the standard sample rate of 44100 and bit rate of 32. To change the sample rate before recording select the Project Rate (Hz) scroll down menu in the bottom left corner.
Recording a New File
If you simply click the Record button in the main tool bar a track window or new file instantly appears and starts recording.
Since this doesn’t give you time to get a level before recording you may want to just test the levels with the first recording. Then Stop. Skip back to the beginning. Listen to the playback in your headphones by hitting the Play button or spacebar. Use the VU Meters on the Meter Toolbar to get the correct recording level. If it’s a good level proceed with the recording a second time by hitting the record button.
Once the new track has been created you will be able to see the track’s sample rate and bit rate, and engage with the mute and solo buttons as well as the Audio Track Menu.
Opening an existing track
Go to File – Import – Audio or CTRL-Shift-I to open an existing file.
When opening an existing file a menu will pop up asking if you want to Make a copy of the file to edit: selecting this means that Audacity will run a little bit slower, but it will always have its own copy of any audio you are using in a project so the original file or the project can never be affected if the source files are accidently moved or deleted.
Combining tracks into one file
Select the Time Shift Tool. Now you can adjust the position of one track or the other until they’re the way you want them. You can even move tracks around while they’re playing. To align two tracks together or reset their time shift back to zero, use the Align Tracks Together or Align with Zero commands in the Track menu.
If you want to change the volume in one track so it sounds similar to the others use the gain controls on the tracks.
You can also Mix tracks over each other. Choose the Time Shift tool and adjust the position of one track or the other until they’re synchronized the way you want them.
If you hear clipping which wasn’t present in either of the original files, it means that the combined volume of the two tracks is too loud. Use the gain controls on the tracks to reduce the volumes until you don’t hear clipping anymore and have a good mix.
Note that using a variety of files at different sample rates will result in variance in the pitch of the tracks. You can resample any track by going to Tracks – Resample and selecting the matching sample rate of the rest of the files.
Going to File – Save Project enables you to saves the current Audacity project (AUP) file. Audacity projects are not intended to be read by other programs, but they are extremely fast to load and save within Audacity. When you are finished working on a project and you want to be able to use it in another program, select one of the Export commands instead.
To export a file go to File – Export. This allows you to export your project into one specific standard audio file such as WAV or MP3. You can change the format of exported files in the Preferences scroll down. If there are multiple tracks in your project, they will be automatically mixed in the exported data. To export only a single track or part of a track, use Export Selection instead.
Noise reduction in audacity
This effect is ideal for removing constant background noise such as fans, tape noise, or hums. It will not work very well for removing talking or music in the background.
Removing noise is a two-step process. In the first step, you select a portion of your sound which contains all noise and no signal, in other words, select the part that’s silent except for the noise. Then choose Noise Removal from the Effect menu and click Get Profile. Audacity learns from this selection what the noise sounds like, so it knows what to filter out later.
Then, select all of the audio where you want the noise removed from and choose Noise Removal again. This time, click the “Remove Noise” button. It may take a few seconds or longer depending on how much you selected.
If too much or not enough noise was removed, you can Undo (from the Edit menu) and try Noise Removal again with a different noise removal level. You don’t have to get a new noise profile again if you think the first one was fine.
Removing noise usually results in some distortion. There’s virtually nothing you can do about it. When there’s only a little bit of noise, and the signal (voice) is much louder than the noise, this effect works well and there’s very little audible distortion. But when the noise is very loud, when the noise is variable, or when the signal is not much louder than the noise, then the result is often too distorted.