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Author David Luebbert
Posted 4/22/11; 12:51:16 AM
Msg# 5786 (top msg in thread)
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Concepts that can help one make sense of rhythms

In the design of the SongTrellis Play Rhythm service and of the site's Rhythm Web, which collects listener-recommended rhythms that were auditioned via Play Rhythm, I made distinctions between rhythm orchestrations (or rhythm performances), rhythm signatures, and rhythm skeleton counts.

Rhythm signatures and skeleton counts are not standard concepts taught by those who practice music analysis, but concepts that I invented to aid my own understanding of the rhythms that are played in rhythm traditions that inherit from Africa.

Rhythm Orchestrations

Orchestration in the context of musical composition is the process of deciding when particular instruments will play parts in a musical composition and which pitch ranges those instruments will use to realize their parts.

A rhythm orchestration, as I use the term, is a rhythm description that precisely describes the percussion sound of every hit in a rhythm cycle.

The description character string in the rhythm= parameter of a Rhythm Orchestration played by a Play Rhythm request, will contain alphabetic symbols such as B to specify when a Bass drum tone should sound, a O (capital oh) to specify when a drum Tone should sound. (The symbol for the hand drum sound called Tone is an O, because that character is a diagram of where you strike a drum to make such a sound, on the hard outer edge of the drum that lies underneath a circular drum head's outside edge). S means that a slap drum sound should be performed.

There are several other one and two character symbol sequences that could be invoked within a rhythm performance that invoke other characteristic drum and percussion sounds that should be played (H, T, r, So, Ss, X).

Without appropriate mental tools, I always needed to consult printed notation laying in front of me to perform a rhythm that I wanted to play

When I first took hand drum lessons 20 years ago, for my first year, no rhythm that Bill Matthews taught me stuck. I could not remember a rhythm and play it from memory. I was totally chained to my notation book, Bill's Conga Joy, to follow the rhythms that I needed to play when I practiced with my drum group. If I forgot my book, I was lost.

Building the tools

I had to learn to analyze and abstract the rhythms I was learning to play so that I could identify ideas that were used as the building blocks of different ensemble rhythms, and that were shared inside of seemingly different rhythm parts. Once I could do this, and I could think of their constituent chunks, rhythms became memorable. Then I could start to retain them and play them and flow from one rhythm to another during performances. For me, this was the key to learning how to play fluently.

Two concepts were my handles for remembering rhythms; my keys for playing fluently

First concept: the Rhythm Signature

The first thing I had to realize was that the actual sequence of different drum sounds in a rhythm is not what felt strongest in my muscle memory and what held most firmly in my ear when I played a rhythm or listened to it.

Instead it was the pattern of hits, the knowledge of when to move my arms and hands, and when to stay still that was most memorable.

Before I could learn to accurately play the sequence 'bass-rest-tone-slap', I had to have the idea 'hit-rest-hit-hit' firmly in mind first.

I would learn the rhythm as though it were played using only a single drum pitch, hitting the drum at the correct instants in a cycle, before I would learn to move my hand around the drum to slap out a particular series of drum pitches.

When it was time to design the rhythm descriptions that Play Rhythm would understand, I designed Play Rhythm's little rhythm description language so it would be easy to first think of rhythms as a series of hits encoded via 1 and 0 symbols. Then I could relate to that hit series many different performances and many different orchestrations of that rhythm.

To orchestrate a rhythm, I would replace 0 symbols with '*' symbols, and 1 symbols with specific drum pitch symbols.

A Rhythm Orchestration that has been flattened down to a series of timed hits I call a Rhythm Signature. Within the Rhythm Web, all of the many different ways that signature can be orchestrated are recorded as members of that signature's family.

The symbols in a Rhythm Signature are always some punctuated sequence of 1 and 0 symbols, like this:


In the notation of a rhythm signature, 1 symbols are instructions to make a sound and 0 symbols are instructions to stay quiet in particular beat subdivision. The dash symbols delimit beat boundaries. The first symbol of a beat group is played on its beat.

In the Rhythm Web, when we look at the report for a particular performance of a Rhythm Orchestration, it will list its rhythm signature.

When you look at the report of a rhythm signature it will include a link to a list of all of the Orchestrations that have been submitted that share that Rhythm Signature.

What are the Skeleton Counts that the Play Rhythm service reports?

Skeleton Counts were the most important handle I needed to remember rhythms.
Perhaps you'll find that they help you also.

After I had played for awhile, I could sense that certain rhythms that had different signatures still produced similar sensations that made it seem that they were part of an even larger rhythm family.

What I finally figured out was that rhythms are heard as periods of sound interspersed with periods of silence.

When I was learning a rhythm that had an African heritage, each beat was subdivided the same, usually by 4 or by 3. Most rhythm cycles were sequences of 4 beats that were either subdivided by 4 or by 3. A 4 beat rhythm with beats divided by 4 would have 16 subdivision slots and a 4 beat with beats divided by 3 would have 12 subdivision slots.

If there were a sequence of hits that sounded on a sequence of these smallest rhythm cycle subdivisions with no rests between hits, I would hear this string of hits as a unit and it would seem that any rest subdivisions that followed were added on as the ending punctuation for this aural unit.

When a hit sounded after one or more rest subdivisions, that would mark the beginning another section of the rhythm.

Using this idea, I could partition any rhythm cycle in a series of sections. If a rhythm had total of 16 subdivisions, I would hear a sequence of sections that each lasted a certain number of subdivisions. I could then mentally notice that a rhythm might have a pattern of sections whose count went 3+3+3+2+2+3 or 3+5+5+2+1.

Then I realized that the rhythms that sounded like closest relatives were those that had the same shaped cycle of sections. I call these shared sequences of subdivision counts that define different families of rhythms, the Skeleton Counts for those rhythm families.

In a Skeleton Count, extraneous hits were left out of the rhythm, leaving behind only the single hits that started each unit of the rhythm. This would skeletonize the rhythm, allowing you to sense the common feeling of a particular rhythm family in its clearest form.

Once I knew the feeling of a particular Skelton Count, I could easily figure out in my heads other rhythms from that family that had busier rhythm signatures but which affected listeners similarly, because they shared the same Skeleton Count.

And then by gluing together adjacent sections of a Skelton Count, or breaking a Skeleton Count section into smaller parts. I could figure out other rhythm families that were more loosely related to an particular rhythm family.

Using Skeleton Counts, you could mentally build a family tree for rhythms that let you predict how they and their relatives would likely feel if you decided to play them.

I found that Skeleton Counts were even more memorable than a rhythm's signature. Once I could remember rhythms and mentally organize them by Skeleton Count, I could start to solo as I would perform a rhythm with a particular count, and follow it with rhythms that were relatives or that were great contrasts, sculpting my own rhythms as I played.

You'll notice that for every rhythm reported in the Rhythm Web, the Skeleton Count for the rhythm is also reported.

To summarize, think of a Skelton Count as the sparsest possible rhythm of all of the rhythms in a Skeleton Count family. All hits have been left out except for the single hits that signal the starts of new groups within a rhythm.

When you feel like you need to play a more active, dense version of a skeleton rhythm, you can hit on additional adjacent subdivisions after the one that begins the group. You can add as many additional adjacent hits in the group as long as you do not eliminate the very last rest of a group.

Filling up every subdivision slot with a hit has the effect of gluing two groups together and erases the rest that serves as punctuation between groups, thereby producing a rhythm that is a little less related than if you had respected the rhythm's Skeleton Count boundaries.

If you can ensure that the hits in the next group are going to be performed using a different instrumental pitch, then you may fill in the final rest of a nearly full group, because then the pitch change serves to mark the beginning of a new group as we listen.

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Last update: Friday, April 22, 2011 at 2:18 AM.