As a corollary to the above point, I found that students tended to do unnecessary actions more often than professionals, and with greater muscle tension. These actions included movements such as pushing and pulling at the music stand, scratching, touching their hair, etc. These unnecessary gestures possibly provide a cue to nervousness as well as inexperience; some unnecessary actions are certainly natural and normal, but the student subjects tend to perform them more often than the professionals. In the cases where the student subjects adjusted their stands, the movement upwards or downwards was frequently accompanied by a gesture to push the stand away. Perhaps the students had not developed a sense for where they wanted the stand to be or were afraid of hitting it by accident. A more general explanation for this is that people tend to push things away when they feel aversive or repulsed, and perhaps the stand is unconsciously used to demonstrate that feeling.
For example, S2 begins her session by rubbing her brow, pushing her stand away from her, and taking a step back while pulling up her baton with force. These actions possibly indicate nervousness or aversion, and S2’s right biceps EMG signal from this segment is shown below:
In another example from a student subject, S3 pulls up her stand forcefully after several minutes of conducting. There is no apparent reason for this action and no need to use such force for the action; her right biceps EMG signal from that event is shown below in Figure 30:
The student subjects also exhibited many other unnecessary actions such as twitches, apparently due to nervousness and lack of control. Compared with the amplitudes of signal-carrying gestures, the amplitudes of these are high and could interfere with musicians’ perception. S3 tended to often place her left hand on her head or touch her hair with her left arm, as shown below in Figure 31:
In another example, S1 scratches his back with right hand (EMG2) and shakes left hand (EMG 0). These signals are relatively much larger than the beats that preceded them; the beats are located in samples 0-300, the back-scratching signal is in samples 400-900 of EMG2, and the hand-shake is in samples 800-1200 of EMG1. These signals are shown in Figure 32, below:
One conclusion from the above evidence might be that, for the students, the relative signal-to-noise ratio of their gestural content is low. This might not be due to low signal content, but rather to the high noise floor. Perhaps one way in which people train to become professionals is by actively reducing their noise threshold while also improving the reliability of their signals. It might be that a signal-processing paradigm, applied to the study and performance of music, would help musicians to clarify and improve upon their performance.