An MPA file is an audio file compressed using the MPEG-1 Audio Layer 2 codec (abbreviated as MP2). An earlier version of the more popular MP3, the MP2 was developed in the late '80s as part of an effort to standardize digital audio and video for use on Video CDs and digital transmission. MP2 is considered less prone to encoding error than MP3, so is still often used for broadcasting purposes.
MPA files can be played in many of the same applications that play MP3 files. For instance, iTunes, Windows Media Player and Quicktime all feature MPA compatibility. However, iPods and similar portable media devices often have difficulty playing MPA files.
MPA files may not be widely used, but anything created under the MP2 technology tends to have fewer errors (skips, static, or extraneous noises) than anything created as an MP3. Radio broadcasters frequently rely on MPAs and some DVD recorders record sound as an MPA or MP2 file.
As an update of all MP2 file types, MP3s compress the audio more efficiently than MPAs, allowing the same sound quality in a smaller file size. For the average user wishing to listen to music on a computer or portable device, MPAs offer little practical advantage, appealing only to a niche market.
Luckily for users stuck with MPA files, converting those outdated files to MP3s is a relatively hassle-free process. To do so one must first download and install the free Audacity audio editor and LAME MP3 Encoder, both of which are available for PCs or Macs in the Resources section below. Open the MPA file in Audacity and select "Export As MP3..." from the "File" menu. If Audacity asks you to locate the "lame_enc.dll" file, find it in the LAME folder you just installed. Save the MP3 anywhere you like and you're done. You may discard the original MPA.