Dynamics refer to the volume at which music is played. Just as pitch is linked with the frequency of sound waves, volume is linked with their amplitude. However, just as pitch differs from frequency because it depends on perception, volume varies from amplitude in the same way. Amplitude is a physical property of sound that can be measured, but perceived volume is not directly linked with amplitude. Low pitches, for example, are perceived as being much more quiet than high pitches of the same amplitude.
Like so many things in music, dynamics are usually indicated in Italian. Often abbreviations for the Italian names are used, as in the chart below.
Any dynamic can be modified by additional adjectives:
- sempre piano e dolce - always quiet and sweet
- f espressivo - loud, expressive
- più forte - stronger (louder)
- p assai - very quiet (an alternative to pp, or indicating a dynamic between p and pp)
A composer may change the dynamic of a piece at any time by simply placing a dynamic name (mezzo piano) or abbreviation (mp) in the score. However, sometimes the composer will also want to indicate how the performer should transition to that dynamic.
When a composer wants to indicate a sudden and dramatic change in dynamics, he may prefix any dynamic with the term subito (literally 'suddenly') as in subito piano or subito fortissimo.
For slow transitions between dynamics, a composer must use a crescendo or a decrescendo (diminuendo). A crescendo is used for gradually getting louder, and a decrescendo or diminuendo is used for gradually getting softer. These may be indicated with the terms themselves, by abbreviations (cresc., decresc., dim.), or graphically. The graphic representation of crescendos and decrescendos are < and > signs (sometimes called 'hairpins') which are placed below the staff lines and are stretched out underneath the notes that should be included in the dynamic change. Intuitively, < is used for a crescendo and > is used for a decrescendo.
Changes in dynamics can also be modified by additional adjectives:
- diminuendo poco a poco - becoming quiet, little by little
- molto crescendo - becoming louder quickly
- decrescendo al niente - becoming quiet to the point of silence, fading to nothing