Figure 3: The mechanism of the waveform. The thyroid cartilage passes between the two coils during laryngeal elevation, and the distance between the coils decreases (P1 to N2). Then, the coils are pushed out by the anterior movement of the larynx (N2 to P3). Finally, the thyroid cartilage moves posteroinferiorly (P3 to N4), and the thyroid cartilage moves downward, returning to its starting position (N4 to P5). The upper solid arrow represents the distance between the coils, and the lower broken arrow represents the movements of the thyroid cartilage.