Tone contour
Tone contours are numbers that represent the way a pitch varies over a syllable. Their invention is attributed Yuen Ren Chao. If you visualise a stave of music, there are five horizontal lines. Each representing a different pitch level. The lowest pitch level is numbered 1, the next lowest 2, .... and the highest pitch would be numbered 5.
The Mandarin third tone has a tone contour /213/, showing a pitch which dips and then rises.
Level tone contours are /11/, /22/, /33/, /44/ and /55/.
Falling tone contours like /51/, /31/, /51/ etc
Rising tone contours /13/, /35/, /15/ etc
