Recording your voice over a song is a great way to make a demo, practice singing a song, or create a parody of a song. Doing so is a relatively easy process with the help of a free audio recording program such as GarageBand for Macs. GarageBand’s user-friendly interface allows you to easily import a song, record your voice and export your recording without having any prior experience recording your voice.
Open GarageBand on your Mac. GarageBand only works on the Mac OS X operating system because it's developed by Apple.
Create a new session by clicking “File,” selecting “New,” choosing “New Music Project,” naming the project and clicking “Create.”
Add a song to your GarageBand session by dragging and dropping the music file for the song into the GarageBand edit window.
Create a new vocal track to record to by clicking “Track,” “New Track," selecting “Real Instrument” and clicking “Create.”
Rename the new track, “Vocal.”
Use a built-in microphone on your computer or plug in an external microphone to your computer. To hook up an external microphone, plug the XLR cable into the microphone and attach the 1/8-inch stereo mini plug adapter to the other end of the XLR cable. Then plug the 1/8-inch mini plug into the “line in” input of your computer.
Click the Apple symbol located in the top left-hand corner of your computer screen and select “System Preferences.”
Choose the “Sound” category and select the “Input” tab.
Choose “Internal Microphone” if you are using your computer’s built-in microphone. Choose “Line” if you are using an external microphone.
Exit out of the “Sound” menu.
Return to GarageBand and press the record button on the vocal track to arm it for recording. After doing so, the button will turn red.
Press the "Master" record button at the top of GarageBand when ready to record. The button will turn red when GarageBand has started recording. Talk or sing into the microphone to record your voice over the song you imported. When you are finished recording, press the space-bar to stop. The "Master" record button will no longer glow red when GarageBand is no longer recording.
Rewind to the beginning of the song by pressing and holding the double-arrowed rewind button. Press the play button to hear your vocal performance--adjust the relative volumes of your voice and the song by moving the volume fader up or down on each track. When you are happy with the mix between the two, export the song by clicking “Share” and then selecting “Export Song to Disk.”
Name the file, select where you’d like to save it and then click “Save.” You have now successfully recorded your voice over a song.