A changing tone
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 neighbor tones or double neighbor tones. Changing tones appear to resemble two consecutive neighbor tones: an upper neighbor and a lower neighbor with the chord tone missing from the middle. The changing tone functions as a way to decorate or embellish a chord tone.