There are four different mp3 files that make up Unsilent Night. You may download one, some or all, but to make Unsilent Night work, you only play one of the four when it is time to start your procession. Play in the mp3 player of your choice, burn to a CD or copy to a cassette tape for your boombox.
(If you are having trouble downloading via the above links, try these alternates:)
There is also a custom designed app for iOS and Android players/phones. The app contains all four tracks, and pressing play starts one of the four at random (N.B. because of the audio files, these are large apps and you will need to be on a Wi-Fi network to download and install them). If you are using this, or one of the mp3 files in your digital player, you will need an external speakers. There are a number of good, inexpensive self-powered speakers that attach directly to the audio out of an iPod/iPad/iPhone/Android phone, a good place to start looking for one is through this Amazon saved search.