In his series How Music Works, Howard Goodall presents theories that rhythm recalls how we walk and the heartbeat we heard in the womb. However neither would seem to have any survival value in Man’s evolution. More likely is that a simple pulse or di-dah beat recalls the footsteps of another person.
In Western music, rhythms are usually arranged with respect to a time signature, partially signifying a meter. The speed of the underlying pulse, called the beat, is the tempo. The tempo is usually measured in ‘beats per minute’ (bpm); 60 bpm means a speed of one beat per second. The length of the meter, or metric unit (usually corresponding with measure length), is usually grouped into either two or three beats, being called duple meter and triple meter, respectively. If each beat is grouped in two, it is simple meter, if in three compound meter. According to Pierre Boulez, beat structures beyond four are “simply not natural”.
A beat is the basic time unit of a piece of music; for example, each tick sounded by a metronome would correspond to a beat. More technically, “the beat is the pulse of the mensural level”[1], also known as the beat level[2], the metric level at which pulses are heard as the basic unit–”the denominator of the meter signature,” admitting compound meters. Depending on the context, beat may denote either
- the onset of the corresponding time unit, a point in time, the very moment when the metronome ticks, or
- the complete time interval between two consecutive taps, so to say, or
- in popular music, the whole sequence of individual beats (in the sense of meter, rhythm, groove, or riddim). In hip hop music, the term ‘beat’ has come to be defined as the entire instrumental, non-vocal portion of the song.