Conductors act as guides to the orchestras or choirs they conduct. They choose the works to be performed and study their scores, to which they may make certain adjustments (e.g., regarding tempo, articulation, phrasing, repetitions of sections, and so on), work out their interpretation, and relay their vision to the performers. They may also attend to organizational matters, such as scheduling rehearsals, planning a concert season, hearing auditions and selecting members, and promoting their ensemble in the media. Orchestras, choirs, concert bands and other sizable musical ensembles such as big bands are usually led by conductors.