Why does the conductor of singing draw a semicircle in the air?

The orchestra's live circle drawing has two functions. One is to beat the time. You must learn the beat of music. If I remember correctly, there are seven or eight different gestures indicating different beats.

Another function is to prompt performance, because there are more than a dozen people in the small band, and each musician is responsible for different chapters. If there is a tacit team, there is no need to carry out it. If there is no seamless coherence and tacit understanding, it is necessary to carry out a point.

Therefore, the role of the conductor is generally only responsible for controlling the beat and occasionally coordinating the consistency of the action.

Finally, if there is tacit understanding, if there is a high degree of tacit understanding, there is no need for command at all. But it is very difficult, really very difficult, especially for large symphonies. The cooperative band may not be a team yet.