Expert or fraud, the powerful person in front of an orchestra or choir attracts both hate and admiration. But what is the actual influence a conductor has on the musician and the sounding result? To throw light on the fundamental principles of this special gestural language, we try to prove a direct correlation between the conductor's gestures, muscle tension, and the physically measurable reactions of musicians in onset-precision, muscle tension, and sound quality. We also measure whether the mere form of these gestures causes different levels of stress or arousal. With this research we aim not only to contribute to the development of a theoretical framework on conducting, but also to enable a precise mapping of gestural parameters in order to develop and demonstrate a new system to the optional enhancement of musical learning, performance, and expression.