Standardisation of the piano pedals

Pedals have existed in pianos since the eighteenth century. It took many decades however before piano designers settled on the three pedals, following the configuration standardised by Steinway and Sons beginning in the late nineteenth century. From left to right, the three pedals are commonly referred to as the una corda pedal, the sostenuto pedal and the sustain pedal.

The purpose of the sostenuto pedal can be varied with the instrument. In most modern grand pianos, the sostenuto pedal only sustains dampers that are lifted when the pedal is engaged. This effect gives impression of a third hand, because the player can employ both of his or her hands to the playing while the sostenuto pedal keeps the chosen notes ringing. In some upright pianos, the tone is softened with a piece of felt which is lowered between the hammers and the strings, which makes the pedal act as a practice pedal.

The una corda pedal in grand piano is functioned by shifting the keyboard and hammers to the right so that one less string would be struck. The use of the una corda pedal can decrease the loudness, but the more significant effect is the change in timbre as the coupling between the strings does not remain the same. Unlike the grand piano, the una corda pedal of the upright piano makes the output sound softer through moving the action closer to the strings.

The sustian pedal, sometimes referred to as the damper pedal or forte pedal, is the most commonly used pedal in a modern piano. It lifts all the dampers and sets all strings into vibration due to sympathetic resonance and the energy transmission via the bridge. This allows the strings to keep vibrating after the key is released. Hence the sound rings as long as the sustain pedal is held down.

Pedalling techniques and notations

Mirroring the development of the pedals themselves, the notations used for indicating pedalling techniques have likewise changed over the centuries.The use of the pedals was not marked in musical scores before the 1790s. Composers like Chopin and Liszt marked pedal onset and offset times actively in their compositions. In contrast, Debussy and Scriabin rarely notated pedalling despite its importance in the performance of their works. Yet, they as well as later composers continued to find new sounds through the assumed use of pedals.

Pedalling techniques can vary in timing and the depth of pedal press and release. This is especially the case for the sustain pedal. Pianists apply various pedalling techniques on the sustain pedal to colour the resonance subtly, leading to expressive performance. There are three main pedalling techniques related to timing, i.e., when the pedal should be pressed. Rhythmic pedalling corresponds to pressing the pedal at the same time as the keys. This supports metrical accentuation, an important aspect of Classical era performance. Pressing the pedal immediately after the note attack is called legato pedalling. This enables the performer to produce seamless legato. Anticipatory pedalling can only be applied after a silence and before the notes are played. This is primarily used by pianists to produce greater resonance at the commencement of the sound.

In terms of pedal depth, "depressed" and "released" are the two conventional positions of the pedal. When the pedal is depressed the dampers are removed from the stings and the stings can vibrate freely. When the pedal is released, the dampers rest on the stings and stop their vibrations completely. It is possible, however, to imply the pedal also in intermediate positions. When the pedal is kept in an intermediate position, the dampers will allow the strings to vibrate to some extent but will prevent the strings from vibrating freely. Thus a tone will be heard in full strength while the key is held down. When the key is released, the volume will be reduced but some sound remains. We shall use the German work "Nachklang" when referring to this remainder of sound. The volume of the "Nachklang" depends upon the position of the dampers. Scarcely any "Nachklang" remains when the dampers are nearly touching the strings, while practically the full volume of sound remains when the dampers are almost completely removed from the strings. All gradations can be obtained by moving the pedal between these two positions.

Apart from "full pedal", Schnabel defined another three levels of part-pedalling which are referred to as "1/4 pedal", "1/2 pedal" and "3/4 pedal". It should be noted that these terms do not refer to specific positions of the pedal, nor even to specific positions of the dampers, but only to the amount of sound which remains when the keys are released. The only way to recognise these pedals, to distinguish between them or to judge whether they are performed correctly, is by hearing the effect created as Schnabel discussed. To test whether a certain position of the pedal produces the effect of "1/4 pedal" accurately, play a scale or a succession of different harmonies: there should be no blurring until the last note has been played; play the same passage again, but without pedal: there should be a marked difference in sound. To test "1/2 pedal", play single staccato notes or chords: they should sound staccato; play a scale or succession of different harmonies: there should be some blurring. To test "3/4 pedal", play a chord, then release the keys: it should sound as if the chord were held out; play and releases the same chord again, using full pedal, there should be a marked difference in sound. Many special effects can be created by changing directly from one intermediate position to another, or between intermediate and full pedal. For example, a rapid diminuendo in a harmonic passage can be achieved by releasing the pedal gradually, thereby passing all intermediate positions.

Throughout the twentieth century, composers became increasingly more precise in providing pedalling instructions to performers. On one hand, while there were many experiments in more explicit notations, real standardisation to indicate the large variety of pedalling techniques has not emerged. On the other hand, experts agree that pedalling in the same piano passage can be executed in many different ways even if pedal markings are given. This is influenced by the performer's sense of tempo, dynamics, textural balance, and the settings or milieu in which the performance takes place. A common statement is that the pedal should be released when the harmony changes. We shall conclude that recognising and notating pedal use can benefit many applications, including automatic pedalling transcription or educational purposes.