handles Zadok the priest introduction may change its chords but the rhythm is pretty constant in Philip Glass's opera a cannot enrich in 250 years later we hear a similar pattern but this time there is a subtle but significant difference [Music] what's happening to Philip Glass's chugging along rhythm is a trick perfected by African musicians centuries ago the pulse isn't changing but as the pattern repeats and repeats something else is changing a musical jargon we say that the accent is shifting [Music] accent is the fourth key element in rhythm along with pulse tempo and the subdivision of the beat so we better find out what it is and how it works accent is all about which beats are important and which are not the important ones gets stressed the others fitting neatly between let me show you by using the running technique of Olympian athlete a be a Yeti pan as an example because Abby's a human and not a machine one of her legs is Mssr is stronger than the other so she leads off onto her right foot those two steps right left right left are the nucleus of all our rhythm strong weak strong weak we've accented the first beat in a pair and the minute will repeat the motion we have created our first groove so fundamental to our rhythmic instinct are these accents that we even imagine them when they don't actually exist we can't help ourselves listen to this pulse which could be the ticking of a clock listen for long enough and you'll find yourself organizing this ticking into groups of two or four your brain automatically gives one of the beats an emphasis by default as it continues you might even start to hear favorite tunes in your head ticking along to this pulse with all their imported accents but there's no accent or emphasis in this electronically generated beat at all and Olympia fixed it so there wasn't your brain has superimposed a hierarchy on the beat it has created a virtual accent you can if you like take any collection of equal beats and give one other than special emphasis so if you had eight beats to play with you could divide them into two groups of four and put an accent on the beginning of each like handle does in Zadok the priest while philip glass starts off his Akasha and Prelude with the same grouping of four as handle pretty soon he starts to change where the accent falls so it turns into this latest to alter this [Music] finally this [Music] this trick of shifting accents was the rhythmic device of choice for the so-called minimalist composers in western classical music in the second half of the 20th century but this had been meat and veg for African musicians for thousands of years where they might improvise for hours on end making subtle and incremental changes to the accents every so often we've made a pulse we've played around with its speed we've subdivided it into smaller units and we've given those units accents our voyage of rhythmic discovery is almost complete but not quite subdividing beats in giving them accents has one important side effect that has given an extra charge to rythm of excitement and energy over the centuries but particularly in the 20th and 21st this side effect is called syncopation its musics red light district where rhythm gets noose playful and mischievous syncopation was a term cropped up a lot in the 1920s during the jazz boom to describe Jazz's new jerky rhythms they believe it or not both the term and the phenomenon had been around for ages syncopation is a musical sleight of hand whereby you sneakily shift a bit slightly ahead of Australia behind where you expect it to be it makes music sound more fun basically instead of sounding mechanical mathematical and a machine like it makes things sound human and quirky here's a simple example from bark it's a short keyboard piece and invention and this is what it would sound like without it's syncopation [Music] but this is what bar actually wrote my right hand the upper part is being deliberately delayed by a half beat all the way through the phrase this in its crudest form is syncopation [Music] there it can be found in classical music it's much more common in folk and popular music [Music] in East European gypsy music this type of syncopation is called estin the accordion is half a beat behind the violin playing catch-up giving the music an urgent momentum [Music] because we develop a sense of steady rhythm as infants you might think we'd rebel against a style of music that shifts the beat from where it really should be but no we seem to like the way a syncopation plays around and teases our expectations rhythmic tricks like this excite and delight us [Music] [Applause] syncopation really came into its own though in America with the emergence of ragtime music in the late 19th century [Music] [Applause] [Music] work time grew out of marching band music in around the 1890s where the beat was steady and loud and bashed out by drums you can't mess about delaying beats in marching music unless you want your marches to trip over themselves but when musicians wanted to imitate popular marches on the piano alone they had to make certain compromises so the other part a compliment that the tumors and the trombones took in the band had to be covered entirely by the left hand like this still the beat is completely regular no syncopations here but the poor old right hand has to somehow cover not just the tune but all the other frilly bits at the Piccolo's clarinets and cornets share out amongst them the solution was a pyro style that did a bit of chewy and a bit of frilly at the same time and the only way it worked was by hopping from one to the other dislocating or syncopating the rhythm in the process an unintended jerkiness was thus added to the music everyone liked the jerkiness the syncopation so it's stuck [Music] rag times syncopation just like box all that of the Gypsy Stan followed strict rules whereby each delay was of a predictable or identical length but then something mysterious and magical happened a new breed of music grew out of ragtime and what distinguished it was that its syncopation wasn't predictable but it became elasticated this new breed of music was jazz and the elastication of the syncopation which took place over a period of about a decade can thanks to old recordings be seen unfolding in front of our eyes this type of syncopation came to be known as Swing [Music]