Article: Many of the instruments used to perform medieval music still exist, but in different forms. Medieval instruments included the wood flute (which in the 21st century is made of metal), the recorder and plucked string instruments like the lute. As well, early versions of the organ, fiddle (or vielle), and trombone (called the sackbut) existed. Medieval instruments in Europe had most commonly been used singly, often self accompanied with a drone note, or occasionally in parts. From at least as early as the 13th century through the 15th century there was a division of instruments into haut (loud, shrill, outdoor instruments) and bas (quieter, more intimate instruments).

Now answer this question: Medieval instrument in Europe were commonly used how?
singly