A drum was a musical instrument.
The Doctor was an avid fan of drummers and could play the instrument himself. In one instance, the Doctor's first four incarnations attempted to form a band but found difficulties as they all wanted to play drums. (COMIC: Day of the Tune) The Eleventh Doctor later noted a fondness for Ringo Starr and wondered why few others thought of him highly. (GAME: City of the Daleks)
The Master constantly heard the sound of drums in his head ever since he looked into the Untempered Schism as a boy. (TV: The Sound of Drums) This noise was implanted by Rassilon in his efforts to escape the final day of the Last Great Time War, fearing the absolute destruction of Gallifrey. (TV: The End of Time) The Master played the drums in Gallifrey Academy Hot Five. (PROSE: Deadly Reunion)