Shuāng yīn 双音 (trad. 雙音) “Double Note”

For two adjacent strings, bend the lower string so its pitch rises to match the higher string. Use the thumb or index finger to sweep across both strings, in a gesture away from the performer. Pressing the lower string after it is struck and creating an audible slide is a different technique called huayin shuangyin (Kwok).

This may be considered the name of the category. Ferguson’s source A adds that using the index finger is its own named technique: Qiè 切. Kao says the shandong school refers to using the thumb in this way as Lín Xián Tóngyīn 邻弦同音 “Adjacent Strings in Unison”.