A neighbor group
consists of two consecutive nonchord tones
. The first moves up by a step from a chord tone, skips down to another non-chord tone, and then resolves to the original chord tone. These two non-chord tones are often called changing tones or double neighbor tones. Neighbor groups appear to resemble two consecutive neighbor tones
: an upper neighbor and a lower neighbor with the chord tone missing from the middle. The neighbor group functions as a way to decorate or embellish a chord tone.