These are the audio files for Nativity Carol. Download the file for your part, plus the file that is just called Nativity Carol, which has all parts.
An MP3 player should recognise the files as being part of an album called MCC Christmas 13 with artist Medina Community Choir.
In terms of instruments used, sopranos and altos are violin, tenors and basses bassoon. The sound is also panned in the stereo field, so sopranos and altos are fully on the left side; and tenors and basses fully on the right side.