Pulse (music)
Encyclopedia
In music
Music
Music is an art form whose medium is sound and silence. Its common elements are pitch , rhythm , dynamics, and the sonic qualities of timbre and texture...

 and music theory
Music theory
Music theory is the study of how music works. It examines the language and notation of music. It seeks to identify patterns and structures in composers' techniques across or within genres, styles, or historical periods...

, the pulse or tactus consists of beat
Beat (music)
The beat is the basic unit of time in music, the pulse of the mensural level . In popular use, the beat can refer to a variety of related concepts including: tempo, meter, rhythm and groove...

s in a (repeating) series of identical yet distinct periodic
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

 short-duration stimuli
Stimulus (physiology)
In physiology, a stimulus is a detectable change in the internal or external environment. The ability of an organism or organ to respond to external stimuli is called sensitivity....

 perceived as points in time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....

 occurring at the mensural level. This pulse has a tempo
Tempo
In musical terminology, tempo is the speed or pace of a given piece. Tempo is a crucial element of any musical composition, as it can affect the mood and difficulty of a piece.-Measuring tempo:...

 to which listeners entrain as they tap their foot or dance along with a piece of music (Handel, 1989), and is colloquially termed the 'beat,' or more technically the 'tactus'

Definitions

The pulse may be audible or implied. The tempo
Tempo
In musical terminology, tempo is the speed or pace of a given piece. Tempo is a crucial element of any musical composition, as it can affect the mood and difficulty of a piece.-Measuring tempo:...

 of the piece is the speed of the pulse. If a pulse becomes too fast it would become a drone
Drone (music)
In music, a drone is a harmonic or monophonic effect or accompaniment where a note or chord is continuously sounded throughout most or all of a piece. The word drone is also used to refer to any part of a musical instrument that is just used to produce such an effect.-A musical effect:A drone...

; one that is too slow would be perceived as unconnected sounds. When the period of any continuous beat is faster than 8-10 per second or slower than 1 per 1.5 – 2 seconds, it cannot be perceived as such. "Musical" pulses are generally specified in the range 40 to 240 beats per minute. The pulse is not necessarily the fastest or the slowest component of the rhythm
Rhythm
Rhythm may be generally defined as a "movement marked by the regulated succession of strong and weak elements, or of opposite or different conditions." This general meaning of regular recurrence or pattern in time may be applied to a wide variety of cyclical natural phenomena having a periodicity or...

 but the one that is perceived as basic. This is currently most often designated as a crotchet or quarter note
Quarter note
A quarter note or crotchet is a note played for one quarter of the duration of a whole note . Often people will say that a crotchet is one beat, however, this is not always correct, as the beat is indicated by the time signature of the music; a quarter note may or may not be the beat...

 when written down (see time signature
Time signature
The time signature is a notational convention used in Western musical notation to specify how many beats are in each measure and which note value constitutes one beat....

).

Pulse groups

While ideal pulses are identical, when pulses are variously accented
Accent (music)
In music, an accent is an emphasis placed on a particular note,either as a result of its context or specifically indicated by an accent mark.Accents contribute to the articulation and prosody of a performance of a musical phrase....

, this produces two- or three-pulse pulse groups such as strong-weak and strong-weak-weak and any longer group may be broken into such groups of two and three. In fact there is a natural tendency to perceptually group or differentiate an ideal pulse in this way. A repetitive, regularly accented pulse-group is called a meter
Metre (music)
Meter or metre is a term that music has inherited from the rhythmic element of poetry where it means the number of lines in a verse, the number of syllables in each line and the arrangement of those syllables as long or short, accented or unaccented...

. Pulse groups may be distinguished as synchronous
Synchronization
Synchronization is timekeeping which requires the coordination of events to operate a system in unison. The familiar conductor of an orchestra serves to keep the orchestra in time....

, if all pulses on slower levels coincide with those on faster levels, and nonsynchronous, if not.

An isochronal or equally spaced pulse on one level that uses varied pulse groups (rather than just one pulse group the whole piece) create a pulse on the (slower) multiple level that is non-isochronal (a stream of 2+3... at the eighth note level would create a pulse of a quarter note+dotted quarter note as its multiple level).
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