Rap Theory

Music Theory

Rhythm is essential to rap. Music theory concepts and terminology are essential to understanding the rhythmic organization of rap flow. "Rhythm" concerns the timing of events: when things happen, how long they last, and how far apart they are. In instrumental music, the rhythmic events are called "notes"; in vocal music, like rap flow, the rhythmic "events" are syllables.

Meter

The rhythms of music are organized in relation to an abstract framework called meter. Meter is not something that is audible...it is not really part of the music. Meter is a organizing structure that we feel when we make, or listen to, music.

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Beat

The fundamental rhythmic structure that underlies musical meter, and thus rhythm, is the beat. A beat is a regular pulse. The speed at which the pulses occur is called the tempo. We measure tempo in "Beats Per Minute" or BPM for short.

A series of dots like this one

BPM

can help us illustrate the idea of a pulse. Click the square to the left to hear a click at the beat's tempo; Adjust the slider to see/hear different tempos.

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Metric hierarchy

Musical meter is created by multiple different beats pulsing in synchrony. Each beat makes one level in the meter; we say that slower beats are "higher" level and faster beats "lower" level. The key is that each beat level is exactly twice the speed of the lower level. Thus, each higher (slower) beat aligns with the every other lower (faster) beat.

Whenever multiple beat levels align, those beats are strengthened. The more levels align, the stronger the beat. This creates a hierarchy of stronger and weaker beats. Whenever a "high level" (slow) beat occurs, it is strengthened by all the lower level beats.

The diagram below illustrates a metric hierarchy of five beat levels. Each level has it's own tempo, which is always twice the tempo of the level above.

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Tactus

When we listen to music we usually focus on one "main" beat; the beat you'd tap your foot or bounce to. This main beat is called the tactus. Determining which level is the tactus is subjective; not everyone will always agree. However, people generally prefer to pick a beat level with a tempo between 70 and 120 bpm as the tactus.

Take the dot plot graph above and try to feel different levels of the hierarchy is the tactus.

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Measures

It is useful to keep track of how many beats have elapsed at various metric levels. The most common approach is to simply count along with the tactus beat level. However, rather than just counting to infinity, we jump back to one every few beats. Since the beat levels in the metric hierarchy are all related by two, counting in powers of two is most useful: 2, 4, 8, or 16. There is no "correct" way of counting; you can choose whatever beat level you want, and count whatever power of two you want. However, the most common approach is to count to four on tactus beats. Every group of four tactus beats is called a measure or a bar. The dots below illustrate various ways of counting the meter.

BPM

Counting like this, we can actually keep track of multiple beat levels at the same time:
We keep track of the tactus with every number we count: "1 2 3 4."
We keep track of the level above the tactus with every odd number "1 2 3 4."
Finally, the next highest level (two above the tactus) is marked by every one: "1 2 3 4."
This beat is called the downbeat.

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Subdivisions

The measure level is a higher, slower, level than the tactus. Levels below, faster, than the tactus are called subdivisions. Musicians have developed a few handy techniques for counting subdivisions, without losing track of higher metric levels: To count the level immediately below the tactus, we add an "and" in between each tactus beat. To count two levels below the tactus, we add "e," "and," "a," between each tactus beat.

BPM
Triplets

Subdivisions are little bit more flexible than higher metric levels. Specifically, sometimes a metric level below the tactus moves at triple the speed, instead of double. These are called triplets. Triplets can divide the tactus itself into three, as so

BPM

or divide the level below the tactus into three, so that there are six beats per tactus:

BPM

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Hypermeter

Levels of the metric hierarchy that are slower than the measure-level are called hypermeter: hypermeter includes pulses at 2, 4, 8, or 16 measures. The fastest hyper-metric pulse, every 2 measures, is very easy to hear and feel and it is essential to rhythmic organization: Every other downbeat is perceived as slightly stronger. Slower hypermeters are relatively abstract: they pulse so slowly that is impossible to really feel them as beats. Still, these levels give music structure by creating groups of four, eight, or sixteen measures. These groups are highly important to the structure of flow: they form natural boundaries in music. Usually, emcees will use these boundaries to structure their flow: for instance, an emcee might rap two couplets about one topic (4 measures), then two more couplets on another topic (4 measures), creating a 8-measure group. Rapping three couplets (for a total of six measures) does not work as well.

Higher hypermetric levels are slightly more difficult to perceive, but can still play very important roles in rap. Thus, 8 or 16 measure groups (multiples of 8) are more stable than 12 or 20 measure groups. The highest hypermetric grouping that we really perceive at all is the 16-measure level: most rap songs feature 16 measure verses.

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Rhythm

So far, we've only discussed beats and meter, which are abstract things that we feel, not things we really hear. Rhythms are what we actually hear when we listen to music. Emcees rap their syllables timed to match the metric hierarchy. However, unlike meter which stays stable and unchanging throughout, the rhythms of flow can stop and start and jump around between metric levels.

To understand and discuss the rhythm of flow, we need to consider two things: 1) the inter-onset-interval of each syllable.
2) the metric position of each syllable.

Inter-onset-interval

The inter-onset-interval of each syllable is the time from the beginning of one syllable to the beginning of the next syllable. Since rhythm is timed to a metric grid, the IOIs of syllables in rap will match the speed of various beat levels in the metric hierarchy. So if the tactus beat is at 80bpm, an emcee might rap syllables at 80, 160, or 320 syllables per second. By mixing and matching various shorter and longer IOIs, the emcee can create a variety of rhythmic patterns. Any given rhythm will primarily jump between two metric pulses that are separated by one level, like 80 and 160. Thus, for any given rhythm we can think of rhythmic patterns as mixes of two syllable IOIs, a "short" IOI and a "long" IOI. We can then talk about rhythmic patterns as combinations of short (S) and long (L) syllables.

Lets consider how we could rap the words "throw your hands up in the air." They could be rapped all at the same speed, simply repeating "S" syllables.

Throw your hands up in the air

or, they could be rapped with the repeated pattern "L-S-S"

Throw your hands up in the air

or "S-L-S"

Throw your hands up in the air

or just "L-S."

Throw your hands up in the air

The possibilities are endless!

Metric position

The other rhythmic consideration is where syllables land in the metric grid. Above, we considered four different ways to rap the phrase "throw your hands up in the air." Let's take the "L-S-S" pattern and consider how it could be rapped against the meter.

Throw your hands up in the air Throw your hands up in the air back to top

Syncopation

Often, emcees deliver their syllables in a way that matches the metric hierarchy. For instance, placing the longest, most important syllables on strong metric positions. However, rhythms can also be delivered in a way which conflicsts with the metric grid. This is called syncopation. To be precise, a syncopated syllable is a syllable that happens on relatively weak metric position, which is not followed by a syllable on the next strong position. Compare the following delivery of "throw your hands up in the air" to the two above.

Throw sync your hands up sync in sync the air weak (strong) weak (strong) weak strong weak strong weak (strong)

In this example, the words "throw," "up," and "in" are delivered as syncopations. The syncopation of "in" is especially strong, since the difference between the weak and strong metric positions is greater. Neither "your" nor "the" are syncopated, even though they are on weak beats. Finally, "hands" is not syncopated because it is on a stronger beat than the following syllable.

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Cross-rhythm

We've already learned that we can create triplets by dividing beats into three instead of two. However, another technique is to group beats in groups of three. By default, the metric hierarchy groups everything in units of two. If the emcee chooses to group rhythms in groups of three beats, they create a cross-rhythm. Cross-rhythms imply a new, pseudo-beat level, which cuts against the main meat levels at 1.5.

Don"t push me "cause I"m close to the edge. 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

Notice that cross-rhythms create a variety of syncopations, with a few non-syncopated syllables.

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