How do I reduce the size of an mp3?

Here are two articles to help you reduce the size of your mp3:

http://www.ehow.com/how_6484248_reduce-mp3-size-itunes.html

https://www.techwalla.com/articles/how-to-compress-mp3-files-on-a-mac

The reduction in file size does not reduce the quality of the recording from the listener's point of view; it is only detectable when you are editing an audio file.