The above contain MIDI files which will play directly on a Windows PC and probably also on an Android smartphone or tablet.
Mac users should download the files (that happens automatically when you click on the file) and open them using the free Musescore 2 application to listen and see the score as they play. If you want to play them on an iPhone or iPad, use File/Save Online... in Musescore and create an account (save the files as private in case of copyright problems). The companion Musescore App in the iOS App Store will allow you to play the files.
The files on this site are MP3 files, which should play on any computer, smartphone or tablet.
So far, we have not found a source of practice files for Messaien O Sacrum Convivium but if anyone with time on her or his hands wants to put in the soprano, alto or tenor part, here is a Musescore file with the correct time signatures, lyrics and bass part. Click on the link to download it. If you have a Windows PC or Linux computer, you can download a free copy of Musescore 2 from the same location as above. Please email me (Ian Downie) to let me know you intend to work on it and I will update this page to show which parts are being entered.