This lesson concerns Consonance and Dissonance and just to define these terms, again, at the outset Consonance means a tone combination that we like and Dissonance means a tone combination that we don't like. And I should say right at the beginning that an individual tone, think of playing a single tone on the piano. It really is meaningless with respect to Consonance and Dissonance. When we talk about Consonance and Dissonance, we're talking about tone combinations. In the simplest case, two tones played together and of course they're a much more complicated chords that we'll on some occasion to discuss. So let's listen as Ruby demonstrates the 12 chromatic dyads. The simplest tone combinations that form a chord that have the sense of or we like it, that sounds good or we like it less. Incidentally, I mean, the consonance and dissonance over the range of musical tones, is roll towards the consonant end of things. I mean, we don't play things for the most part that sound terrible. Dissonance just means relatively less consonant, doesn't mean horrible. So here's really playing these 12 chromatic diads, and you'll appreciate what consonance and dissonance means as she demonstrates these. [MUSIC] So now, let's turn to a formal consideration of what consonance and dissonance tones are, in terms of their ranking. So, this is something that goes back a long way, demonstrating the relative appeal of chromatic dyads. And you can see from the references that are listed here along the right hand side of this slide that these classical studies all are late 19th century, early 20th century studies. As people asked, in that era, how can we formally denote the relative consonance or dissonance of dyads? So here is the octave interval and what all of these studies have done is to ask what's the relative consonance? What's the relative appreciation of the appeal of these total combinations? And the graph here shows what in these various studies, all of these studies being aimed at the same thing using somewhat different techniques and instruments, and so on. What the relative consonance is of the different intervals in the chromatic scale. So this interval, P8, is the octave. This, a perfect fifth, perfect fourth, major third, and so on for all of these intervals down to the major seventh and the minor second which are the least consonant of these intervals. Again, this notation is the notation in the standard western scale. But music around the world has some similar kind of notation, maybe expressed in a little bit different way. So the point of this is that the intervals that are most consonant in all of these studies are quite definite. The octave, the perfect fifth and the perfect fourth, those intervals are appreciated as the most consonant, the second most consonant, third most consonant. After that things get a little bit murky and you can see that in these various studies that have been done. There is a good deal of variation in the consonance ranking that subjects express. So the consonants, the degree in which you subjectively like the tone combination, goes down or the chromatic scale, in this order. But as you can see, it gets kind of murky in the more dissonant end of the studies that have sought to rank this. But it's generally the case that this ranking that's shown here is on average the ranking that in these different studies people indicate. As the tone that to them sounds best, using of the octave most consonant and the tone that sounds most dissonant which is the major seventh or the minor second down at the opposite end. But you can see that there's a huge amount of variation. As people try to rank, in some systematic way, their appreciation of these less consonant tones.
