This from KVR: An introduction to ornamental, unessential and non-harmony notes (http://www.kvraudio.com/forum/viewtopic.php?t=168736)

Ornaments and unessential notes

An ornament is one or more notes which decorate or embellish a musical line. Some ornaments involve non-harmony notes, but some do not. - It is possible to ornament a melody whilst still using notes which fit with the harmony (for example, a consonant skip). Sometimes special signs are used for ornaments, other times they are written out in full. In times gone by, ornaments would not be notated, but would be improvised by the performer. Nowadays, it is common to notate all ornaments.

This post will primarily focus on non-harmony notes, with only a brief discussion of some of the more common ornaments. For more details on ornamental notes, consult my Introduction to Ornamentation Marks.

Notes: Accented can mean two things. Where every beat has a different chord, accented means 'on the beat'. Where harmony lasts longer though, accented means 'on a strong beat'. (The strong bears in 4/4 are the 1st and 3rd). Unaccented is the opposite. Where every beat has a different chord, unaccented means 'off the beat'. Where harmony lasts longer though, unaccented means 'on a weak beat'. (The weak beats in 4/4 are the 2nd and 4th). Step/Leap: A 'step' is the interval of a 2nd (either major or minor). - Usually I mean a diatonic step, which means to the nearest note contained within the key (whether or not that is a tone or semitone away). A 'leap' is any interval of a 3rd or more.

NON-HARMONY NOTES

Passing Notes These are probably the most common type of non-harmony notes. There are two types: Unaccented Passing Notes, and Accented Passing Notes (see above). They fill the gap between two pitches.

Unaccented Passing Notes These are probably the most common type of passing note. In chorale harmony, commonly one passing note is inserted between consonant pitches a 3rd apart.

Accented Passing Notes These are a type of appoggiatura, and are not as common as unaccented passing notes. They are usually found in descending scalic passages, but can sometimes occur ascending. In chorale harmony, one passing note may be inserted between consonant pitches a 3rd apart. Usually the note before the accented passing note will be a consonance, however it is possible to have an accented passing note after an unaccented passing note in a scalic passage. The resolution note must not be struck simultaneously with the passing note, except if it is in the bass.

Generally, passing notes are usually diatonic notes (which fit with the key), but chromatic passing notes are also possible. These use notes which do not belong to the key.

In 4-part harmony, you should never use more than two simultaneous passing notes in different parts. Parallel passing notes (parallel motion in different parts) are only allowed in 3rds or 6ths. (Including compound 3rds and 6ths). Appoggiaturas There are many different sorts of appoggiatura (it is both an ornament and a non-harmony note), and this can sometimes lead to confusion. Appoggiaturas are an accented dissonance, resolving (usually downwards, but not always) by step to a consonance. Generally, the chord in which the appoggiatura occurs should not contain the resolution note, unless that note is in the bass and the chord is in root position. The note before the appoggiatura is usually a consonance. Like passing notes, appoggiaturas can be either diatonic or chromatic.

Appoggiaturas lean onto their resolution note. There are 'short' and 'long' appoggiaturas. The 'short' appoggiatura is similar to an 'acciaccatura' (see below). The 'long' appoggiatura generally takes half the value of the resolution note (or three-quarters of its value if it is dotted). Most often, the resolution note is longer than the note preceding it (without the appoggiatura). Appoggiaturas are generally slurred to their resolution note. They are often reserved for moments of drama in the work (particularly in vocal music). Sometimes, appoggiaturas occur in several parts at the same time, in which case the chord is referred to as an appoggiatura chord.

Appoggiaturas can be approached by step or by leap. When approached by step, they are similar to accented passing notes. They are most often used in descending passages where the note before the appggiatura is usually either the same note or one note higher. This resolves down by diatonic step to a consonance. Sometimes they may occur in an ascending passage (usually leading note to tonic), where the note before the appoggiatura is usually either the same note, or one note lower. This resolves up by a semitone (thus, it may have to be chromatically altered).

When approached by leap, the leap is usually in the opposite direction to the resolution step. Most common is a leap up to the appoggiatura, which resolves down by step. A leap down to the appoggiatura is also possible, in which case it must resolve up by step.

Essentially, appogiaturas are unprepared suspensions or retardations (see below).

Double Appoggiatura This is where an ascending and descending appoggiatura occur consecutively, in either order. (Ie, a discord moving up or down a 3rd onto another discord, which resolves to

a concord by step in the opposite direction. This can be any rhythm, and sometimes either note may linger for any length of time above the same harmony.

Example of appoggiaturas:

Auxiliary Notes Also called a neighbour note, this is a note inserted between two adjacent notes of the same pitch. The auxiliary note is either a step above, or a step below this note. They are usually unaccented, but may occasionally be found accented. The auxiliary note may move either one tone, or one semitone, - thus it may either be diatonic or chromatic. The term Chromatic Auxiliary Note is used when the note does not belong to the key. When the auxiliary note is above the harmony note, it is called an Upper Auxiliary Note, and when it's below, it's called a Lower Auxiliary Note. Upper auxiliary notes are almost always diatonic. Lower auxiliary notes may be chromatic (sharpened, never flattened). Auxiliary notes must not produce a semitone (or compound semitone) between any parts, - if this would be the case, the auxiliary note should be sharpened. An auxiliary note below the root of a chord should always be a semitone below (sharpened if necessary), unless that root falls a third onto a consonance.

Examples of auxiliary notes:

Turn This is a type of ornament that includes both a lower and upper auxiliary note in succession. Also be called a Double Auxiliary Note. This can be either a 5-note figure, where the 1st 3rd and 5th notes are the (same) concord note, and the 2nd and 4th notes are a step above, and a step below this note. Or, it could be a 4-note figure, missing out the initial concord note. - Generally, you start with the note above the concord note, but you can also start with the note below it, in which case it's called an Inverted Turn.

Examples of Turns:

Changing Note Figure Similar to a Turn, a changing note figure (sometimes just called 'changing tones'), is a double appoggiatura preceded by the concord resolution note. Thus, it is a 4-note figure, beginning and ending on the same note, with the middle two discord notes a step above and a step below the concord note (a 3rd apart from each other). The second note is unaccented, the third note may be accented or unaccented. It is sometimes refereed to as a 'double auxiliary' note (as it contains both upper and lower auxiliary notes).

Example of a changing note figure:

Nota Cambiata A nota cambiata is also called an exchanged note, or simply a cambiata. It is identical to a Changing Note Figure, except the first note is a 3rd higher or lower than the final concord note (rather than the same note). The second note is always a step away from the first, with the third note a 3rd away from the 2nd.

Note: The nomenclature varies enormously here. Some people say a nota cambiata is the same as a changing note figure, but others differentiate between them. - Some people refer to a nota cambiata as a (type of) Turn and lump the two together. - Other definitions exist too. The essential fact is that a nota cambiata involves leaping a 3rd from a dissonant note (which differs from most dissonances which are quitted by step).

Example of Nota Cambiatas:

Anticipation This is a short unaccentednote, inserted immediately before a note of the same pitch. The note before this anticipation is usually a diatonic step above or below (but approach by leap is also possible).

Example of anticipation:

Suspensions Probably one of the trickiest, but best sounding of all the non-harmony notes. A suspension is similar to an appoggiatura, in that it is a accented discord. There are three stages to a suspension, all of which must occur in order in the same part. Preparation:The suspended note must occur in the preceding chord as a consonance in the same part. Suspension: The chord changes, but the note remains in the same part. This must create an accented dissonance.

Resolution: The suspend note moves downwards a diatonic step onto an unaccented consonance.

Usually the suspension and resolution occur over the same chord. However, a chord change is possible as long as the resolution note occurs in both chords. The resolution note must not occur in any part of the suspension chord, except if this part is the bass. Suspensions are named after the intervals of the relevant notes above the bass. For example, a 4-3 suspension means the suspended note is a 4th above the bass, which resolves down to a 3rd above the bass. (Or it could be a compound 4th and 3rd, ie, an 11th and 10th) 4-3 suspensions are generally best (but never with an augmented 4th), and 7-6 and 9-8 suspensions are good too. Avoid 2-1 suspensions; they seldom sound good. Ornamental resolutions (involving, for example, more non-harmony notes) are possible. The suspension is often tied to the preparation note, but it doesn't have to be.

Examples of suspensions:

Retardation This is exactly the same as a suspension, except it resolves upwards by diatonic step, instead of downwards. (Although some people do not distinguish between the names, referring to retardations as a different form of suspension). Usually, a (usually 4-3) suspension occurs below the retardation in a different voice.

Example of retardation:

Echappée Also called escape tone, this is an unaccented discord between two consonant notes a diatonic step apart (either up or down). The echappée is one diatonic step away from the first note, and resolves a 3rd to the second note. The echappée is thus always in the opposite direction of melodic movement, and is a rare example of a non-harmony note that resolves by leap, not by step.

Examples of Echappées:

ORNAMENTS

Acciacctura Also called a 'crushed' note. This is a type of ornament, and is not generally written out. It is usually a short note, coming either on the beat, or immediately before (depending on style). Usually the acciacctura is a diatonic step above the note it resolves to. It is usually notated as a small note with a diagonal line crossed through the stem. - When written such, it does not count as part of the duration of the bar. (Thus, a 4/4 bar may have 4 crotchets, and any number of acciaccturas in.)

The Acciacctura:

Mordent This is another ornament that is rarely written out. This is an embellishment to a single note. First, you play the note that's written, but then, very quickly you play a short note a diatonic step above or below it, which immediately resolves back to the starting note again. Where the mordent is a step above the note, it is called an upper mordent or inverted mordent. Where it is a step below, it is called a lower mordent (or just 'mordent'). The speed of the mordent (and thus the duration of both the initial and extra note) is dependant on the tempo of the music.

The mordent:

There are many more ornaments (especially in Baroque music), and the nomenclature varies depending on the time and country of composition. The interpretation often varies also, but you do not generally need to worry about this when composing modern music. For more details on ornamental notes, consult my Introduction to Ornamentation Marks.

Consonant skip This is not a non-harmony note. Just the opposite in fact. A consonant skip does exactly that; it leaps from one consonance to another consonance (over the same chord).

Example of a consonant skip:

There. Now you know many ways to add interest to your music!

Note that sometimes combinations of two or more non-harmony notes and/or ornaments occur consecutively (For example, an appoggiatura might precede a turn or mordent).----Unfamiliar words can be looked up in my Glossary of musical terms. Also check out my Introduction to Music Theory.