The easiest way to record sounds on the Macintosh is to use the QuickTime Player app that is included with every Macintosh.
Launch the QuickTime Player app:
To record, select File > New Audio Recording
This opens up the recording window:
To record, click the red "record" button in the middle. Then click on that button (now a square "stop" button) to end your recording. After recording, you can play your recording:
If you are happy with your recording, Save it (File > Save)
You now have an audio file that is in the .m4a format which is compatible with Boom. Upload it to your deck and enjoy!
Note: Quicktime creates fairly large, very high-quality recordings. Sometimes these files are too large for Boom or slow your deck down. If you need to make a smaller version of your recording, please follow the steps in the Notes section of this solution.