The conductor typically stands on a raised podium with a large music stand for the full score, which contains the musical notation for all the instruments and voices. Since the mid-18th century, most conductors have not played an instrument when conducting, although in earlier periods of classical music history, leading an ensemble while playing an instrument was common. In Baroque music from the 1600s to the 1750s, the group would typically be led by the harpsichordist or first violinist (see concertmaster), an approach that in modern times has been revived by several music directors for music from this period. Conducting while playing a piano or synthesizer may also be done with musical theatre pit orchestras. Communication is typically non-verbal during a performance (this is strictly the case in art music, but in jazz big bands or large pop ensembles, there may be occasional spoken instructions, such as a "count in"). However, in rehearsals, frequent interruptions allow the conductor to give verbal directions as to how the music should be played or sung.