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”.

Use the thumb and index finger to pluck two adjacent strings in a closing motion, the lower bent to produce the same pitch as the higher. This may be related to Niǎn 捻, an alternating pattern.

Sweep the thumb across both strings in a gesture towards the performer.

Sweep the thumb across both strings in a gesture away from the performer.

Sweep the thumb across two open strings in a gesture away from the performer. Press the lower string to match the pitch after it is struck, creating an audible slide.

Ferguson lists this as equivalent to Chongtuo but the term huayin suggests a slide should be audible.

Sweep the thumb across two strings in a gesture away from the performer. Just after the strings are struck the left hand releases the lower-pitched string for an audible downward slide.

There is some disagreement as to this term. Kwok says it is using the index finger and thumb to pluck two adjacent strings bent to the same pitch with a closing motion, seemingly similar to Chòngyīn 重音. If using own nails, Kwok says only the pads of the fingers should contact the strings.

Ferguson says this is using the thumb and index to pluck two adjacent strings in a gesture towards the performer.

A third source found copied around the internet (example: http://www.yueqixuexi.com/guzheng/20170528174868.html) says this is the alternation on two adjacent strings, thumb and index in closing motions, to create an effect similar to a tremolo, but softer.