Manually converting dozens of audio files to MP3 format can be time-consuming, unless you use Audacity's batch convert chain. The chain performs all the procedures necessary to convert any audio file supported by Audacity 2.0 to an MP3 file. The process is completely automated, and Audacity can convert hundreds of files in a folder to MP3 files -- a process that would take you many hours to complete -- in a matter of minutes. Note that the The LAME codec is required for the conversion.
Download the LAME software codec before attempting to convert the audio files to MP3 format. Audacity needs LAME to encode MP3 audio data.
To download LAME, open the MP3 for Audacity page, scroll to the To Download LAME and FFmpeg for Windows section and click the Lame_v3.99.3_for_Windows.exe link.
Double-click the file to start the setup wizard and click Next. You are advised to close all applications -- especially Audacity, if it is running -- before starting the setup, but this is not mandatory.
Click Next if you agree to the terms of the LAME Licensing Agreement to proceed to the next step.
Click Browse if you want to change the destination folder. LAME needs about 2MB of free disk space, so there is no need to change the default folder in most cases. Click Next.
Review the setup settings and click Back if you need to change them. To cancel the setup, click Cancel. Install LAME by clicking the Install button. The wizard installs the program in just a few seconds; click Finish after the process is complete.
Launch Audacity, click File and select Apply Chain from the menu. Audacity comes with a single pre-installed chain: the MP3 Conversion chain.
Select the MP3 Conversion chain from the list of available chains and click the Apply to Files button to apply the chain to an entire folder. If, on the other hand, you wish to convert only the audio tracks in the project, click Apply to Current Project.
Select the folder that contains the audio files and then select the files you want to convert to MP3. Select everything in the folder by pressing Ctrl-A. Select specific items by holding Ctrl and clicking each file. Click Open.
Select the Make a copy of the files before... or Read the files directly option. The first option is safer -- but slower -- because it copies each file into the project and then edits it. The latter option is faster because Audacity reads the files directly from their location without copying them into the project.
Check the Don't warn again... box to prevent Audacity from prompting you to make a choice for every file in the batch. Click OK.
Open the folder that contains the original audio files and then open the Cleaned sub-folder that was created by Audacity to store the MP3 files. Verify the MP3s to ensure the conversion was successful. Do not delete the original files before you verify the results.