Dynamics (music)
In music, the dynamics of a piece are the variation in loudness between notes or phrases. Dynamics are indicated by specific musical notation, often in some detail. However, dynamics markings require interpretation by the performer depending on the musical context:  a specific marking may correspond to a different volume between pieces or even sections of one piece. The execution of dynamics also extends beyond loudness to include changes in timbre and sometimes tempo rubato.

Purpose and interpretation
Dynamics are one of the expressive elements of music. Used effectively, dynamics help musicians sustain variety and interest in a musical performance, and communicate a particular emotional state or feeling.
Dynamic markings are always relative. p (piano - "soft") never indicates a precise level of loudness; it merely indicates that music in a passage so marked should be considerably quieter than f (forte - "loud"). There are many factors affecting the interpretation of a dynamic marking. For instance, the middle of a musical phrase will normally be played louder than the beginning or end, to ensure the phrase is properly shaped, even where a passage is marked p throughout. Similarly, in multi-part music, some voices will naturally be played louder than others, for instance, to emphasize the melody and the bass line, even if a whole passage is marked at one dynamic level. Some instruments are naturally louder than others – for instance, a tuba playing piano will likely be louder than a guitar playing fortissimo, while a high-pitched instrument like the piccolo playing in its upper register can sound loud even when its actual decibel level is lower than that of other instruments.

Dynamic markings
The two basic dynamic indications in music are:

p or piano, meaning "soft or quiet".
f or forte, meaning "loud or strong".More subtle degrees of loudness or softness are indicated by:

mp, standing for mezzo-piano, meaning "moderately quiet".
mf, standing for mezzo-forte, meaning "moderately loud".
più p, standing for più piano and meaning "quieter".
più f, standing for più forte and meaning "louder".Use of up to three consecutive fs or ps is also common:

pp, standing for pianissimo and meaning "very quiet".
ff, standing for fortissimo and meaning "very loud".
ppp ("triple piano"), standing for pianississimo and meaning "very very quiet".
fff ("triple forte"), standing for fortississimo and meaning "very very loud".

Changes
Three Italian words are used to show gradual changes in volume:

crescendo (abbreviated cresc.) translates as "increasing" (literally "growing")
decrescendo (abbreviated to decresc.) translates as "decreasing".
diminuendo (abbreviated dim.) translates as "diminishing".Signs sometimes referred to as "hairpins" are also used to stand for these words (See image). If the angle lines open up (), then the indication is to get louder; if they close gradually (), the indication is to get softer. The following notation indicates music starting moderately strong, then becoming gradually stronger and then gradually quieter:

Hairpins are usually written below the staff (or between the two staves in a grand staff), but are sometimes found above, especially in music for singers or in music with multiple melody lines being played by a single performer. They tend to be used for dynamic changes over a relatively short space of time (at most a few bars), while cresc., decresc. and dim. are generally used for changes over a longer period. Word directions can be extended with dashes to indicate over what time the event should occur, which may be as long as multiple pages. The word morendo ("dying") is also sometimes used for a gradual reduction in dynamics (and tempo).
For greater changes in dynamics, cresc. molto and dim. molto are often used, where molto means "much". Similarly, for more gradual changes poco cresc. and poco dim. are used, where "poco" translates to a little, or alternatively with poco a poco meaning "little by little".
Sudden changes in dynamics may be notated by adding the word subito (meaning "suddenly") as a prefix or suffix to the new dynamic notation. Subito piano (abbreviated  sub. p or sp) ("suddenly soft") indicates that the dynamics quickly, almost abruptly, lower the volume to approximately the p range. It is often purposefully used to subvert the listener's expectation and will signify an intimate expression. Although it uses the piano p dynamic symbol, the performer has slight freedom in their interpretation, causing it to vary based on the preceding loudness or character of the piece. Likewise, subito can be used to mark suddenly louder changes, like subito forte sf, or subito fortissimo sff, however in these cases it is usually only used to add a particular amount of accent to one note or chord.

Accented notes are typically notated with the accent sign > above or below the note, giving it a general emphasis on the attack of the note relative to the current dynamics. A harder and shorter emphasis is usually marked with the marcato mark ^ above the note instead. If a very particular emphasis is needed instead, it can be marked with a variation of subito, forzando/forzato or fortepiano.
forzando/forzato indicates a forceful accent and is abbreviated as fz. To emphasize the effect, it is most often preceded with subito as sfz (subito forzato/forzando, sforzando/sforzato). How these should be interpreted and played in the music is up to the judgement of the performer, but a rule of thumb is that a forzato/forzando can be considered as a variation on marcato while subito forzando/forzato can be considered a variation on marcato with added tenuto.The fortepiano notation fp indicates a forte followed immediately by piano. By contrast, pf is an abbreviation for poco forte, literally "a little loud" but (according to Brahms) meaning with the character of forte, but the sound of piano, though rarely used because of possible confusion with pianoforte.

Extreme dynamic markings
While the typical range of dynamic markings is from ppp to fff, some pieces use additional markings of further emphasis. Extreme dynamic markings imply either an very large dynamic range or very small differences of loudness within a normal range. This kind of usage is most common in orchestral works from the late 19th century onward. Generally, these markings are supported by the orchestration of the work, with heavy forte passages brought to life by having many loud instruments like brass and percussion playing at once.

In Holst's The Planets, ffff occurs twice in "Mars" and once in "Uranus", often punctuated by organ.
Tchaikovsky marks a bassoon solo pppppp (6 ps) in his Pathétique Symphony and uses ffff in passages of his 1812 Overture and his Fifth Symphony. 
The baritone passage "Era la notte" from Verdi's opera Otello uses pppp, though the same spot is marked ppp in the full score.
Sergei Rachmaninoff uses sffff in his Prelude in C♯, Op. 3 No. 2.
Gustav Mahler, in the third movement of his Seventh Symphony, gives the celli and basses a marking of fffff (5 fs), along with a footnote directing 'pluck so hard that the strings hit the wood'.
On the other extreme, Carl Nielsen, in the second movement of his Fifth Symphony, marked a passage for woodwinds a diminuendo to ppppp (5 ps),
György Ligeti uses extreme dynamics in his music: the Cello Concerto begins with a passage marked pppppppp (8 ps), in his Piano Études Étude No. 9 (Vertige) ends with a diminuendo to pppppppp (8 ps), while Étude No. 13 (L'Escalier du Diable) contains a passage marked ffffff (6 fs) that progresses to a ffffffff (8 fs) and his opera Le Grand Macabre has ffffffffff (10 fs) with a stroke of the hammer.

History
On Music, one of the Moralia attributed to the philosopher Plutarch in the first century AD, suggests that ancient Greek musical performance included dynamic transitions – though dynamics receive far less attention in the text than does rhythm or harmony.
The Renaissance composer Giovanni Gabrieli was one of the first to indicate dynamics in music notation. However, much of the use of dynamics in early Baroque music remained implicit and was achieved through a practice called raddoppio ("doubling") and later ripieno ("filling"), which consisted in creating a contrast between a small number of elements and then a larger number of elements (usually in  a ratio of 2:1 or more) to increase the mass of sound. This practice was pivotal to the structuring of instrumental forms such as the concerto grosso and the solo concerto, where a few or one instrument, supported by harmonic basso continuo instruments (organ, lute, theorbo, harpsichord, lirone, and low register strings, such as cello or viola da gamba, often used together) variously alternate or join to create greater contrasts. This practice is usually called terraced dynamics, i.e. the alternation of piano and forte.  
Later baroque musicians, such as Antonio Vivaldi, tended to use more varied dynamics. J.S. Bach used some dynamic terms, including forte, piano, più piano, and pianissimo (although written out as full words), and in some cases it may be that ppp was considered to mean pianissimo in this period.In 1752, Johann Joachim Quantz wrote that "Light and shade must be constantly introduced ... by the incessant interchange of loud and soft." In addition to this, the harpsichord in fact becomes louder or softer depending on the thickness of the musical texture (four notes are louder than two). 
In the Romantic period, composers greatly expanded the vocabulary for describing dynamic changes in their scores. Where Haydn and Mozart specified six levels (pp to ff), Beethoven used also ppp and fff (the latter less frequently), and Brahms used a range of terms to describe the dynamics he wanted. In the slow movement of Brahms's trio for violin, horn and piano (Opus 40), he uses the expressions ppp, molto piano, and quasi niente to express different qualities of quiet. Many Romantic and later composers added più p and più f, making for a total of ten levels between ppp and fff.

An example of how effective contrasting dynamics can be may be found in the overture to Smetana’s opera The Bartered Bride.  The fast scurrying quavers played pianissimo by the second violins form a sharply differentiated background to the incisive thematic statement played fortissimo by the firsts.

Interpretation by notation programs
In some music notation programs, there are default MIDI key velocity values associated with these indications, but more sophisticated programs allow users to change these as needed. These defaults are listed in the following table for some applications, including Apple's Logic Pro 9 (2009–2013), Avid's Sibelius 5 (2007–2009), musescore.org's MuseScore 3.0 (2019), MakeMusic's Finale 26 (2018-2021), and Musitek's SmartScore X2 Pro (2016) and 64 Pro. (2021). MIDI specifies the range of key velocities as an integer between 0 and 127:
The velocity effect on volume depends on the particular instrument. For instance, a grand piano has a much greater volume range than a recorder.

Relation to audio dynamics
The introduction of modern recording techniques has provided alternative ways to control the dynamics of music. Dynamic range compression is used to control the dynamic range of a recording, or a single instrument. This can affect loudness variations, both at the micro- and macro scale. In many contexts, the meaning of the term dynamics is therefore not immediately clear. To distinguish between the different aspects of dynamics, the term performed dynamics can be used to refer to the aspects of music dynamics that is controlled exclusively by the performer.

See also
Accent (music)
Glossary of musical terminology

Notes


== References ==