Figure 2: Panel (i) Visual representation of vectorized monthly activity. All units are radians, not degrees. Months are placed radially on a circle, with January at 0 radians. For each monthly vector \({\overrightarrow{v}}_{i}\), the magnitude of the vector is the number of vocally active hours per month, and the direction of the vector is dictated by the month’s identity. These monthly vectors are used to calculate R. Panel (ii) Visual representation of the directional agreement between years. Panel (iii) Visual representation of the magnitude of the sum of all vectors versus the total magnitude of all vectors.