A novel approach to visualization of tone value pattern

Previous visualizations of tone value patterns primarily relied on pitch curves, which present several issues including excessive intricacies, overlapping graphics, and inconvenience of direct distance comparisons, not only complicating the comprehension of the tone value pattern but also hindering synchronic and diachronic comparisons. Discarding tone curves, this paper introduces a novel visualization method where tone values are mapped one-to-one onto points, with the distance between points reflecting the distance between the corresponding tone values. This method offers a clear and intuitive display of the tone value pattern of a phonology system and the diachronic tone evolution. Through this method, this paper constructs diagrams illustrating the tone evolution of five Chinese dialects (Beijing, Nanjing, Chongqing, Shanghai, and Ningbo) and Standard Thai over the past century, based on prior research. The evolution trends become evident in the diagrams: Beijing, Nanjing, and Chongqing dialects, as well as Thai, exhibit clockwise tone shifts of high > rising > low > falling, whereas Shanghai and Ningbo exhibit counterclockwise trends.

This visualization method employs a rectangular coordinate system rotated 45° counterclockwise. For level tones and simple contour tones, the y-axis signifies the starting height of the tone, while the x-axis signifies the ending height, thereby determining the coordinates corresponding to the tone value. Thus, the vertical direction of the graph represents the average tone height, while the horizontal direction represents the rise (i.e. slope) of the tone. For complex contour tones, the average height and average rise determine the coordinates, and a vertical bar is drawn from the point to indicate the convexity/concavity of the tone. The tone evolution can be illustrated by plotting tone value patterns of different periods on the same diagram and connecting corresponding tones with arrows.