As a first element of sound to explore in this set, we thought of the idea of Timbre. What do you think is interesting about Timbre? For me, Timbre is quite literally the sound of sounds. It's the given quality any particular sound might have. Whether it's rough, or glassy, or sharp. So for example, the C you can play a note and it's going to sound different whether it's on a tuba, or your using a trombone, or it's played on some new keyboard. While the actual pitch might be the same, the Timbre is what gives it that textual quality. And are there particular art works or examples of artists who you think have used Timbre in a particular way or through which we can understand this idea of Timbre? One of the biggest areas in which Timbre plays a role is in actually cover versions of songs. So there's a huge tradition of all sorts of songs being made with acoustic instruments. And then you'll get versions a few years later, a few decades later, replaying the same melodies with the same basic song structure, but the Timbre is different because they're using synthesizers, digital tools, new studio techniques. And so this change in Timbre is what drives a certain type of musical evolution, even though the underlying song structures remain unchanged. And we have clips of cumbia, right, that show his idea of Timbre. It's Marta La Reina. So a classic cumbian melody. And in the first one you'll hear it being played on a type of harpsichord, this lead melody. And then on the second one, completely refigured, is from Grupo La Cumbia five or six years ago. And this is all done with keyboards and synthesizers and a whole new way of electronic music. But the spirit of the song remains the same as it's timbral configuration change. Another hugely important element of sound, is rhythm. Remember in this MOOC, we're not only concerned with the idea of music but also sound in everyday life. So as you think about rhythm and some of the examples will give address this. Don't just think of rhythm as it applies to music but how you experience it in your everyday. The rising sun, like sunset, sunrise heartbeat, breathing, all of these are rhythms and musicians of course have been very inspired by them. But even though we're not musicians and if we're concerned with say urban space, we may pay particular attention to rhythm. There is this fantastic piece with a telephone that you wanted to talk about Jays, but it starts in Africa, right? Exactly. So what is it? The piece we're discussing is by Seth Kranzler. And it's called Steve Reich is Calling. Steve's Reich is an American composer, still active, associated with minimalism. And in the 1960s he went from New York to Ghana, to study all the rhythmic intricacies there. Huge tradition of percussion, rhythm, nuances often tied to life rhythms. And when he came back to New York, one of the things that that inspired him to do, was to think about having different tempos of the same pattern playing at the same time. And so if two rhythms are playing at the same tempo, you might not hear an overlap. But if you shift one to make it slightly faster than the other or slightly slower, very complex patterns can happen very quickly. And Steve Reich made a body of work out of that called fazing music. But then what happened a few years ago, was that there's a wonderful Web based piece of art which is this guy Seth, he put together to iPhones side by side. And they're each playing the ringtone as if Steve Reich is calling you. But the tempo is slightly different. So we can have a listen to this and you can very quickly here what goes from the familiar ringtone to something beautiful and rhythmically abundant. And so Pedro, I think you have something interesting to share with us about Mayan counting systems and their relationship with rhythm. Yes. I mean, the Maya have been famous throughout history for being one of the ancient civilizations who were great astronomers and predicted solar eclipses and also all kinds of comets. But their numbers were different than those of other traditions and they're visually quite characteristic. There's usually four dots that are the number four and then there's a five signifies a line. And to many a contemporary Mayan and people living in the Yucatan Peninsula, what has been left out too often of the scholarship around Mayan numbers, is it's acoustic or soundic systems. Because for them, you can actually tap the rhythms of these numbers. So you can use your finger to do dot dot dot, four and then a clap is the number five. So by just using soft sounds and then a clap, you actually can create this really complex set of numbers, calculations and so on that your ear can perceive. Related to counting and rhythm of course is the idea of synchronization. And who better than a world traveling deejay to talk about it. Yes. Of course, at the basic level synchronization is the ability for musicians to play together, to follow a common rhythm. So if you see a band and they've got the right notes but the thing feels a little off their synchronisation is kind of something's gone wrong with their synchronization. But what deejays do, one of the main ways in which deejays work, is by synchronizing different songs. And so we'll take one song at a specific number of beats per minute and a specific tempo, and then we'll take the second song and adjust it until it's playing with the exact same tempo. And then we line them up so that each of them is looping at the same point in time. And once they're synchronized, it's called beats syncing in DJ terminology. Then you can mix between them and create a third song by the flawless superposition of two different songs. And that's the core of so many different types of dance music that lets you have these long sets where the beat will just blend from one song to another or from one style to another. This idea of unifying the temples underneath, is really critical to that. And in a way at an abstract level, time becomes the art medium, right? Yes. Because you're stretching time in each one of these tracks as you're deejaying. Exactly. Yes, finding that common time.