Channels of Information

February 04, 2021

Music, in its written form, has a high information density. Let’s use this two measure snippet from the start of Sonata No. 3 by Vivaldi (RV 43) as an example.

Measure 1 and 2

There is a lot of information just in these two short measures. The information can be broken down into several channels of information:

The Pitches

Reading from left to right, the first piece of information is the clef. The clef determines where on the staff pitches fall. In our example the clef in use is the bass clef. Cellos have a large range, so cello music is written in three different clefs: bass, tenor, and treble.

While this snippet starts with bass clef, it ends with a clef change to tenor clef. The first note in measure 3 is not an A, it is an E.

The key signature is the next piece of information that determines pitch. In the example there is no visible key signature. By convention this means the piece has no accidentals to alter the pitch of note heads. It’s either in C major or A minor.

With the first note being an A, and the last lowest note also being an A (not shown) we can determine that the piece is in A minor.

Finally the notes themselves determine the pitches that create the music the audience will hear. Since there are no accidentals in the key signature, all the notes are the pitches they appear to be. If, for instance, the key signature had been D Major, with its two sharps, then the third note would not be a C, but rather a C sharp.

So the first channel of information, the pitches, has clef, key signature, accidentals, and note heads as its sources of information.


The next channel of information is the rhythm. Rhythm is notated by using different note heads. The example has quarter, dotted eighth, and sixteenth notes. The rhythm is determined by the ratio of one note to the next. Quarter notes are twice as long as eighth notes. Eighth notes are twice as long as sixteenth notes.

Dotted notes add a wrinkle to the mix. A dotted note, both the A and B in the first measure, have their shown valued plus half that value again. In this case the two dotted eighth notes are half again as long as they would normally be.

If you reduce all the notes shown to sixteenth notes, then the dotted eighth note would each be 3 sixteenth notes in duration.

Contrasted against the rhythm is the pulse of the piece. The time signature that we skipped over earlier determines the pulse. In our example the time signature is 3/4. This means that there are three quarter note pulses per measure.

The example starts with a quarter note, it’s the down beat of that measure. The first dotted eighth note falls on the second beat (pulse). A dotted eighth note plus a sixteenth note equals one quarter note, so the third and final beat (pulse) for measure one happens on the second dotted eighth note.

Juxtaposing rhythm and pulse is perhaps the most difficult part of music for me. These two elements work in concert (ha!) but at times they seem to be at odds with each other.

The second channel of information, rhythm, has the time signature and note heads as its elements.

Note heads are now part of two different channels of information. Their meaning, to borrow from programming, is overloaded. The note heads convey two different pieces of information: the pitch and the rhythm.


Tempo is the next channel. Tempo is the pace of the music. In the example the tempo is broadly hinted at by the word “Largo” above the first note. Largo is a very slow tempo, perhaps 40 - 60 beats per minute. Sometimes there will be an actual metronome marking indicating the tempo.


Bowed string instruments like the cello have another channel of information: articulation. Articulation is how the pitches are produced with the bow, or even finger in the case of pizzicato notes.

When no indication is given otherwise, bowing generally starts with a down bow on the down beat, and alternating bow direction after that. There are several articulation alterations that can, and do, happen.

In the example the 2rd and 3th notes, and the 4th and 5th notes, are played in a hooked fashion. Hooked bowing means that the two notes are played with the same bow direction; down down, or up up, rather the down up. Hooked notes often occur in 3/4 or 6/8 time where dotted notes are immediately followed by their next shorter sibling. Here we have two sets of dotted eighth sixteenth notes. The first is played with two down bows, and the second with two up bows. Hooked bowing is indicated by a slur connecting the notes, and a staccato dot over the second note.

The articulation for hooked bowing is long-short. The dotted note gets a long bow. Then there is a brief stopping of the bow, then a much shorter bow for the staccato note.

While this short example doesn’t show it, there are many other bowing types, each of which alters the sound produced.

Articulation works closely with rhythm to define the sounds produced.

The fourth channel then is articulation, the techniques used to produce the sound.


The final channel is dynamics. Is the music loud or soft? Gradually getting louder or softer? Suddenly changing? While some music has explicit dynamic makings, many pieces do not. And different eras of music (looking at you Baroque) had dynamic conventions that were broadly understood and used. Repeated phrases almost always play the second phrase much softer.

There are both dynamic markings like p (piano) or ff (fortissimo) and expression phrases like “molto expressivo” or “brightly”.

The dynamics channel is where much interpretation occurs, it is where the expression of the music comes to life.

Many Channels, One Sound

All the channels happen simultaneously. They are not only layered on top of one another, they are intertwined, sometimes complexly so. In my musicianship I struggle the most with pulse. Note reading, whether in bass or tenor clef has become nearly second nature now. The basic bowing techniques are also well ingrained. Where my struggles happen is combining several channels at once. It’s like juggling. Three balls is easy, four balls is tricky, five balls is astonishingly hard. A simple rhythm, with few accidentals, and straight forward bowing is like juggling three balls. Once you get the hang of it, it’s easy. Add in some accidentals and some fancier bowing techniques, and a clef change or two; now you are juggling four balls. Add in one more thing, like a fast tempo, or a complex syncopated rhythm, and you’ve got your fifth ball.

Finally, the format of music printed on the page doesn’t always line up with what it sounds like to me. In the example, the last note of measure one, is really a grace note to the first note of measure two. The fact that is is connect by a slur to the previous note, and separated by a bar line from the next note are just artifacts of how music is written down. In a way it is like reading poetry. You don’t pause at the end of the line, you go until the next punctuation mark.

I continue to be fascinated by music and by learning how to play music. That it has complexities only adds to the enjoyment of figuring it out.

Author's profile picture

Mark H. Nichols

I am a husband, cellist, code prole, nerd, technologist, and all around good guy living and working in fly-over country. You should follow me on Twitter.