How to Convert an MP4 to a MP3 in Audacity
An MP4 is a type of computer video file, while an MP3 is an audio file. Audacity is a program for Windows and Linux computers that enables you to record sound. Therefore, if you want to convert an MP4 file into an MP3 file using Audacity, you must play the MP4 file in a media playing program while simultaneously recording the audio using the Audacity software.
Right click on the .MP4 video file you'd like to convert. Click "Open With" then select a media player on your computer that will play the .MP4 video file. Examples include Windows Media Player and Quicktime.
Click "Pause" to immediately pause the .MP4 video file from playing. Rewind it all the way to the beginning so you don't miss any information.
Click the "Record" button in Audacity. Then switch over to the media playing software and click "Play" on the .MP4 video file. The video file will begin to play and Audacity will record its audio information.
Wait for the video to finish playing, then close the media player and click "Stop" in Audacity. Click "File" then "Export as MP3." Name your file and click "Export." A new .MP3 audio file will be created on your computer containing the audio from the .MP4 video file that Audacity just recorded.