All of the following are non chord notes that are effective additions to create a non-harmonic effect and increase the interest and depth of piece of musical composition.

Passing Tones

Used in a harmony line that plays under the melody, a passing tone usually varies from the melody by a whole tone or a third (half tones are sometimes used but not as often) and they are meant to fill in spaces in the melody by forming a connection between one note of the melody, and the next one.  Passing tones allow the music to flow more smoothly.  Although they are fairly simply to play, and even use when improvising, they add depth to the music.  Experiment with passing tones by adding them to chords when you practice. They also happen “under” the melody in harmony — they “pass through” the harmony and therefore create motion.

Appoggiaturas

From the Italian verb “appoggiare” mean to lean upon, appoggiaturas are notes which lengthen the principal note by half its intended length.  They are usually played on the strong beats in the bar, and are usually a whole note either higher or lower than the principal note to which they are grouped.  In modern music manuscripts these will look the same as the other notes on the line, but in early music periods they were printed smaller.  When played within a chord the appoggiatura can create a degree of dissonance, but this is resolved when the principal note is played

Anticipations

These occur when a note belonging to the next chord set is introduced into the current chord being played – creating an anticipation for the chord to come.   Unlike appoggiaturas, anticipations occur on the weak beat, and are usually most effective when used at the end of a musical phrase.

Neighboring Tones

A neighboring tone is a non chordal note that is played at either one tone above or below the chord that follows it.  As it isn’t part of the chord set that follows, it causes a slight dissonance that adds more interest to the music.   When the note is a tone higher, it’s known as either an upper neighboring tone or alternately an upper auxiliary note.  A neighboring tone that is a tone lower than the chord that follows it is known as a lower neighboring tone/lower auxiliary tone.

Suspensions

A suspension is created in three parts.  Firstly comes the preparation (initial play), and then the suspension (held whilst chord changes) and finally the resolution (moves into new chord).  It holds one note from the preceding chord and creates a tone connection between that chord and the next for one note before stepping down into the new chord. 

At first glance these may appear to have the same effect, but listen to chord dominated music while following the manuscript and you’ll learn how to identify anticipations from suspensions, and neighboring tones from appoggiaturas.  The best way to learn how to identify which non-chord tone is which however is to sit at the piano and try them out yourself.  As you play them, you will learn to hear the subtle tone emphasis and variations of each and so be able to identify them easier when listening to a piece of music.