British palace guards are shwon marching with drums.

Musical Rhythm

Some people cannot follow a beat. Such beat deafness, a form of amusia, appears in people who can hear, even in people who can dance, though some can’t clap or dance to a beat. (Here’s more.)

Now, we all do things differently. Perhaps two percent of adults are unable to use mental imagery, and variations in other cognitive skills are scattered through the population: stereoblindness, prosopagnosia, tone deafness, motion blindnesshallucinations, topographagnosia, alexithymia, ambidexterity, dyscalculia, and so on.

But we may be talking about a continent here, more than the usual four percent. There are rhythm tests here, there and yonder if you’re curious. You won’t have to dance.

Let’s focus on rhythm perception to start with, rather than performing or composing. How do you hear a rhythm? Is it just inside your head or does the whole body get involved?

Music may seem like a single perception, but that’s an invention of the mind. There are different musical skills, perhaps five dimensions of music perception and more for performance, that we lump into musicality, which is partly inherited and partly learned and maybe partly personality.

We have a sense of vibration that may have predated the evolution of hearing. In addition, parts of the body resonate to music. (See the post about the voice for more about resonance. The resonant frequency of the chest cavity is 26 to 27 Hz.) It’s becoming popular to talk about many cognitive functions as embodied and emerging from parts of the body outside the brain. The umbrella label for this is “4E cognition”. The embodiment of music tends to rely on a dual-process approach. When we consider musical rhythm, the salient fact is that we not only hear the beat but experience a bodily response as well. It’s the motor response to rhythm that links music to dance, and it’s a tendency that knowledgeable researchers have termed “universal”. (Yes, an appeal to authority is a logical fallacy. At least I’m not claiming to be the authority.)

Ballet dancers are shown performing on stage.

BIO: Rhythm may have evolved before melody. (Some complain that music may end with rhythm as well, although one-note melodies are alive and well.) It is possible that this evolution was partly biological, as some some evidence of genes that influence musical ability has come to light.

Music begins with physical sounds. (Warning: That’s a free ebook*–slow download.) It begins with mechanical vibrations. We know that

We know that music can affect the brain; it’s not cheesecake but a language. Is the brain’s talent for music more heavily inborn, like speech, or mostly acquired, like writing? Researchers can’t identify or retrieve music from brain images, but the mechanism of rhythm processing extends beyond hearing alone, as the brain must generate expectations for clear rhythm processing..

Brain rhythms have been observed to synchronize to musical rhythms not only in adults but in infants as well, though with different techniques, magnetoencephalography (MEG) and electroencephalography (EEG) respectively. However, the MEG findings in adults have been replicated in adults using EEG  here and there.

The entrainment of brain activity by, e.g., light flashes and diurnal cycles, has been known for decades without explaining much yet about how the brain generates rhythmic responses in behavior, but it does raise interesting questions about the mechanisms of brain synchronization. Buzsáki has helpfully placed his introduction to brain rhythms online as an e-book. He has made the interesting argument that some brain rhythms have remained the same in sleep and perception despite big changes in brain size during biological evolution. But be wary of marketing claims (unrelated to Buzsáki) about the terrific effects produced by brain waves as entertainment or therapy, especially if you see mention of binaural beats or Schumann resonances. What you might get for your money instead is a demonstration of the placebo effect or regression to the mean. Always remember that expensive placebos work better.

PSYCHO: Often we refer to rhythm as the beat, while tempo is the overall speed, or the number of beats per minute. Some writers have played up the resemblance between a musical beat and the human pulse rate (about 72 per minute) as significant; but rhythm perception might have other origins.

Rhythm has a hedonic component as well. That is, we like some rhythms more than others. We learn to hear music as beautiful, and our learning determines which rhythms we prefer, perhaps beginning with the language we learn. That is, while creating rhythm may derive from inherited brain mechanisms, our preferences are a gift of culture.

Within our culture and given our level of training, we are all Goldilocks. That is we prefer rhythms that are intermediate in complexity, neither too simple nor too intricate. The association between our liking for a rhythm and its complexity is an inverted-U relationship.

The way we perceive a rhythm’s complexity depends partly on our training in music, and the way we have been trained shapes our response to the rhythm. If you’d like a laugh, here’s Taj Mahal schooling a German audience about clapping on the backbeat.

Our preference for rhythm complexity may, in turn, depend on personality as well as training, or what Greenberg and his colleagues called cognitive style and generalized to more than rhythm. The dimensions along which rhythm preferences varied were systemizing and empathizing. You can test yourself on the scales separately starting with this intro and then the systemizer scale and the empathizer scale.

However, preferences are not skills. The ability to perceive rhythms and improvise depends heavily on working memory, which can shift information around using procedures like place-keeping and updating. Not surprisingly, musicians become pretty good at this. This is not evidence for a “Mozart effect”, which invites skepticism, though there is evidence that music may be important for the development of rhythmic entrainment and social skills, though the best benefits are said to come from performing.

Two interesting sources of rhythm complexity are time signatures and syncopation. After the predictable rhythms of centuries-old dances like the Schottische or a minuet, the syncopation of ragtime is a refreshing surprise, when a note appears earlier than we expected it. (or later than expected. Does syncopation improve this lullaby? Syncopation arises from “off” beats, whether early or late.) Even more complicated rhythms arise in Latin music such as salsa (continued here), enlivened by an Afro-Cuban clave rhythm that may sound complicated to northern ears. Clap your hands as you listen to the clave beat to test your understanding of it.

Sometimes moving to the beat feels like something you’ve done all your life, and sometimes not, but it’s easier with a familiar time signature. Westerners are familiar with duple (2/4 or march) and triple (3/4 or waltz) meter, but quintuple meter, such as 5/4 time, may sound harder to follow, though a Korean who listens to classical court music would probably find quintuple meter quite familiar. Does this show that much of our musical ability has to be learned? Listening to an unfamiliar rhythm, we will tend to remember it as one that we’re familiar with.

Consider the care with which this website introduces us to the simplest of polyrhythms, 2 beats against 3. Then listen to a more complex polyrhythm like salsa or try this, tambú. That is a big leap for a single jump. Adam Neely  starts with the head and enables the feeling to take over later. Edward Chilvers turns it into a manifesto.

SOCIAL: The social nature of rhythm shows up in youngsters as well as adults, and in speech as well as music. Musical rhythm tends to be social, even communicative. It brings people together around the world. Our tendency to join with others in performing a musical rhythm is called entrainment.

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