accompaniment

noun

• 1a musical part which supports or partners an instrument, voice, or group:she sang to a guitar accompaniment [mass noun]:sonatas for piano with violin accompaniment
• a piece of music played as a complement or background to an activity:lush string accompaniments to romantic scenes in films we filed out to the accompaniment of the organ

• 2something that supplements or complements something else:these biscuits are a lovely accompaniment to tea