These are the audio files for Adiemus. Download the file for your part, plus the file that is just called Adiemus, which has all parts.
An MP3 player should recognise the files as being part of an album called MCC July 2013.
In terms of instruments used, the file with all parts has all voice parts using a voice synth, with the accompanying piano and recorder parts. In the individual parts, all the other singing parts are silent, your part is played as a saxophone and the piano is quiet(ish).