Emphasis in Jazz Rhythms
Usually the superimposed rhythms fall into phrases of 3 units, which is set against a background of normal 4/4 rhythm of jazz, as can be heard in these jazz band examples. This is quite different, though superficially similar, from the use of 2 against 3 or 3 against for in European classical music. Here there is no disturbance of normal rhythm. Strong beats remain strong beats. The length of the note groups are the same and the metrical units comprising them differ it is quite different in jazz, where the rhythmic superimpositions produce real syncopation, resulting from the displacement of accents from strong to weak beats.
Applying this to Ragtime, there is a difference between primary and secondary rag. Primary Ragtime is simple syncopation, whereas secondary Ragtime is the superimposition of one, 2, 3 upon the basic one, 2, 3, 4 beat. Some of the devices of jazz rhythms are also found in the Latin American tango. All give an urge to dance, which is even stronger than the emphasis shift that I described above, which is part of Irish and Scottish ceilidh music, but is much weaker in the rather more subdued, elegant and nice English folk dance music.
The superimposition of rhythms has a theoretically limitless number of possibilities, and I should have mentioned Indian classical music along with African music as using this device, sometimes in much more complex forms than even used in jazz. This technique was used by the Broadway composer, Gershwin, in Fascinating Rhythm, is just one example and was also used by the American classical music composer, Aaron Copland in some of his symphonies. Is it that, I wonder that makes Copland's music sounds so American? However the vast majority of "commercial jazz" just use the very basic 3 over 4 superimposition technique, which was in fact what was mostly used by the black American of the southern states.
Getting into the technical stuff, Aaron Copland's view was that pollyrhythm and syncopation were 2 different things, and this was later interpreted by Isaac Goldberg of Tin Pan Alley as meaning that "we may have jazz without any syncopation". This however, is perhaps a matter of what syncopation really means, and their many interpretations. Copland defines pollyrhythm as "a play of 2 independent rhythms". However, syncopation in any extended form also constitutes a "play of 2 independent rhythms" as a different system of accidents is set up against a normal system of accidents.
Is getting a bit complicated now, so let's get back to a basic summary. The basic rhythmic characteristics of ordinary printed sheet music jazz are 2 varieties of syncopation, firstly simple syncopation and secondly, the polyrhythmic superimposition of 3 over 4.
THE STRUCTURE OF JAZZ TUNES.
Although pollyrhythm is a basic part of all kinds of jazz, it is rarely demonstrated in mathematically precise patterns, as would the rhythmic variations in a classical string quartet. Most jazz melodies show some form of polyrhythmic peculiarities. This affects their phrasing and gives that particular form of jazz its character. There are some jazz compositions such as Stumbling and Kitten on the Keys, where pollyrhythm has been used in the exact form. But in general, jazz tunes whether hot jazz or hybrid jazz, use polyrhythmic elements in a free, less mathematical and more subtle manner.
The relationship between the strong and weak piece of musical pulse is always been a part of European music. In jazz, because the importance of syncopation, the effect is very specific in some ways more pronounced. A jazz musician must have a keen sense of where to place subdivided and subordinate accidents in the music he is playing. The jazz musician has to be fully aware of minute changes in the metric units that is quite foreign to European classical music. It's the difference between a genuine jazz vocalist and classical musician who is trying to sing jazz. The first swings and is natural, the 2nd sounds stilted and forced. There is nothing worse than listening to a typical classical orchestra trying to play a piece of music that requires an inbuilt feel for jazz.
THE RHYTHMS OF "HOT JAZZ".
Music is about sparking human emotion, and although it is a fact that many mathematicians seem to be good musicians, music is not mathematical as much as it is psychological. Jazz did not come from black Americans as an intellectual exercise, inventing pollyrhythm and then developing music based on it. Jazz was created by people who had on the whole, no concept of the theory of the music, it was created by black American folk musicians in much the same way as the music of the Irish ceilidh band American barn dance band was created, by people who have a feel for music and its psychology. Musical theory after all is not what creates music, it is just an attempt to explain music that has been created, after the event. Music is created as a byproduct of the way the human brain has evolved. Evolution has developed brains in organisms that have gradually become better at pattern matching, identifying patterns in the natural world around us, in the society's that the organisms living, better at identifying relationships between things and events. Those organisms that can do this the most successfully tend to be fittest for purpose in the evolutionary sense.
One of the organisms that is developed this pattern matching and relationship identification ability, as the human, with one example being the development of natural language. It can be argued that music is just an extension of natural language, though it could perhaps equally well be argued that language is an extension of musical awareness. Whichever way round it is, natural language is more than just words, it is rhythmic patterns, grammatical patterns, patterns of emphasis and tonality. The tonality and emphasis aspects of language are well demonstrated in theatrical training, the example where take a simple sentence, often taking it from a Shakespearean play, and saying that single sentence with this many variations of emphasis and tonality as they can think of, with each variation having a subtly, and some times profoundly different linguistic meaning. A very simple example is:
I am the King!
I am the King?
Whether bold type and underlined word is where the emphasis is. One is an arrogant statement, the other is a puzzled question. Apply this to longer more complex sentences, and all sorts of things change in the meaning. So the human mind is capable of getting great meaning from tonality, pitch and emphasis. This correlates with music, where the accidents, crescendos, change of pitch and rhythm convey quite different feelings and emotions and meanings.
Perhaps the string quartet is the best example, or certainly the purest example, of the refined use of tonality and accidents. Quartet players will argue for hours over the precise freezing of a piece of Mozart, or the flow of romantic composers music, such as Elgar. The whole recording industry is based on these subtle interpretations. Why are there so many recordings of the same string quartet, recorded by different groups of musicians? How does one sell itself above the others? It's all about interpretation. The classical music magazines of always reviewing this recording that recording, or this orchestra or string quartets performance in New York, compared with some other string quartets performance in London. It's all about interpretation, and interpretation is all about emphasis, flow of tonality and all things that add meaning to music in a parallel way to the meaning of natural language. Natural language certainly does have an added element, the word.
A word is nothing more than a label for collection of experiences. The word Apple connects together a whole range of things like, good to eat, about the size of a tennis ball, red or green in colour, surface texture smooth, internal texture white and crunchy, smell is specific, sound it makes if you drop it, cut it, squash it; Apple for the teacher, apple pie, smell of apple pie, taste of apple pie, temperature of apple pie, apple juice, taste and smell apple juice, apple computer, and so it goes on and on. That simple label, the word "Apple" means such a lot.
Music, on the other hand does not have all this connection to a particular note. What it does have is a connection to the creations of emotions. We think of what creates emotions, it could be from site (as you would experience the emotion of fear if you saw a lion walking towards you in the street!). Or it could be from a simple sound, like a gunshot or the squealing of tyres just a short distance behind you, both of which would make you jump, take notice and probably start taking action to save your life. But emotions come from much subtler things. The way somebody speaks to you could be kindly, angry, threatening, spooky. Again going back to the acting exercise, you could say a sentence or phrase in any of these ways, and what would the difference be? It would be largely a matter of the tonality of the voice. Certainly expression of the face, action to the body, the context et cetera would have an effect, and these would be there in a real-life situation or in a film, but think of a radio play. Those emotions of threat, kindliness, happiness, sadness can be conveyed by the radioactive just by the use of their voice. It is this sensitivity of the human brain to tonality in the creation of emotions, that can be used in music.