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Music doesn't always stay at the same tempo, or it could be quite boring! In this guide we'll look at the various ways tempo can change over the course of a piece of music.
Before we look at how music can change tempo, it would be a good idea to read through Tempo: fast and slow, so that you are clear about the concept of tempo and what it means.
Half and double
A very straightforward way for a piece of music to change tempo is simply to switch to half-speed (or double-speed).
This can be done in two ways:
- Switching between cut-common (also known as alla breve) and common time
- Using the marking doppio movimento to "double the movement"
Both of these can be used together, as shown in this example, in which the music goes at twice the tempo after the double bar (the counting remains at the same speed):
It is important to note that in these techniques, the beat remains at a constant speed, but that the number of notes in each beat is doubled.
In the example above, there are initially four crotchet beats in the bar (the speed could be, perhaps, crotchet = 100 or 100bpm), and then after the double bar there are two minim beats in the bar. However, the beat stays the same, at 100bpm, meaning that there are now twice as many crotchets per minute (because there are two crotchets to each minim), and so the music sounds twice as fast!
The tempo can also gradually get faster, rather than suddenly doubling in speed. There are several markings that you will come across that require the player to increase the tempo gradually:
|Gradually get faster|
|stringendo||Squeezing / pressing: getting faster|
|poco a poco più...|
e.g. poco a poco più mosso
|Little by little, more... (little by little, more movement = get faster)|
Often, (in particular with accelerando) you will see these markings with a dotted line stretching over the passage in which the acceleration should take place, until a new steady tempo is reached, as in this example:
Just as the tempo can gradually get faster, it can of course gradually get slower. Here are the most common terms:
|Gradually get slower, becoming slower|
|Broadening (getting slower, louder)|
|poco a poco meno...|
e.g. poco a poco meno mosso
|Little by little, less... (little by little, less movement = get slower)|
Just as with the "get faster" marks, a dotted or dashed line is often used over the relevant music, particularly with "rit." markings, until the new tempo is reached.
Warning! The marking ritenuto should not be confused with ritardando and rallentando. Ritenuto means "held back" (i.e., slower), and takes effect immediately rather than gradually.
It is often necessary in music to temporarily suspend a regular tempo, for expressive effect. There are several common terms indicating this kind of tempo change:
|The performer is "at liberty" to vary the tempo, to embellish the music, or even to improvise around the music.||obbligato|
|liberamente||Freely; in a free tempo or rhythm||giusto|
|Literally "robbed"; disregarding strict time and "robbing" some notes of part of their duration (making them shorter) to add to other notes, making them longer, for expressive effect.|
|cadenza||The marked passage is not in any tempo, and can be embellished. Usually this refers to a solo passage at or just before a final cadence in which the performer can "show off" with musical flourishes.||N/A (music returns to normal notation)|
A cadenza is often not written out in full, and sometimes not at all, in which case only the term cadenza is shown, along with a pause mark over one note. This is an invitation to the player to improvise or add a flourish starting on that note, and returning again to it.
Some notable cadenzas for well-known concertos are written out in full and published separately, and other times they are simply improvised on the spot!
Sometimes, the time signature will change but it might not be obvious how (or even if) the tempo changes. In such cases, it is usual for an extra marking to be added, for clarification.
If the beat length and duration stay the same...
If the time signature changes (e.g., from 2/4 to 3/4), you would see a marking as shown below (simply referred to as "crotchet equals crotchet"):
This marking tells us that a crotchet in the old tempo has the same duration as a crotchet in the new tempo, and in this example, there is not a change in tempo.
In cases like this, you might also see the Italian marking: l'istesso tempo, which means "the same tempo".
If the beat length changes...
Sometimes, the beat length might change but the beat duration remains the same. This is common when going from simple time to compound time (or vice versa), as shown below:
In this case, a crotchet in 2/4 has the same duration as a dotted crotchet in 6/8 - so the beat has the same duration as before, even though its length has changed. In other words, this is also not a change in tempo!
If the beat duration changes...
By contrast, the time signature might remain the same, but the beat length should change by some fixed proportion. This is known as a metric modulation.
In the example below, the music changes from a slow tempo (Adagio) to a faster tempo (Allegro), and the speed changes precisely, such that a quaver in the slow tempo has the same duration as a crotchet in the faster tempo:
Note that in this example, the beat length remains the same, but the beat duration changes - compare this with the previous two examples - this time, there is a change in tempo.