From CS 294-10 Visualization Sp10

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Data Set

To start, I wanted to find a data set that contained the spectral or harmonic content of many songs, so that I could compare them on this level, and see if there is a correlation between this and the popularity of the song. As far as I can tell, this data set does not exist. It was easy to find the billboard charts for any year, but there was very few data sets with any sort of statistical analysis of the music itself. I was starting to write a program that would do such a spectral analysis when I came across a data set with 1200 folk tunes and a lot of statistical analysis at http://www.cs.nott.ac.uk/~ef/music/Statistics.htm. After tediously putting it all in the spreadsheet, I wanted to see if the musical features of the song pointed to the style of folk tune that it was. The differences in the styles are described here: http://www.cs.nott.ac.uk/~ef/music/database.htm.

What is a common feature among the different styles of British folk tunes?

They are mostly pentatonic and almost all diatonic. When I graphed the normalized scale degree frequencies grouped by dance style, in all cases the first five notes belonged to the pentatonic scale (tonic, second, third, fifth, sixth) and this was immediately followed by the seventh and the fourth. All 7 of these notes combine to make the diatonic scale.


At the same time, I graphed the keys that the songs are in on pie charts and found that all of the styles are mostly in G and D.


Which of the styles use the non-diatonic notes the most?

To find this answer, I filtered out all of the non-diatonic notes: minor 7th, augmented 4th, and all other sharps and flats (the data set I collected this from lumped all other notes into two categories, which is very unclear). I placed these four fields into a stacked bar chart. You can clearly see that the magnitude of the Slip Jig is much larger than the rest, meaning it has more non-diatonic notes. This visualization also allows you to see the proportions of non-diatonic notes that make up this sum.


Does the Slip Jig also have the most non-stepwise intervalic leaps?

I thought since there are proportionally the most non-diatonic notes of all the styles that the Slip Jig would also have the most leaps in the melody making it overall, probably the most dissonant sounding style. There is some correlation, though Hornpipes have the most leaps in the melody overall; the Slip Jig came in second place.



For the summation visualization, I wanted to show both the differences and similarities between songs, and be able to make more judgements based on the intervallic leaps, number of non-diatonic tones and the style of folk song. To accomplish this, I made a scatter plot with the % of non-diatonic notes on one axis, and the % of each interval on the other axis; this time I included seconds and unison for comparison. I also colored the points to label each interval, and change the shape for each song type. I think that the color and shape distinctions are easy to see since the song types and the interval size line up pretty well vertically and horizontally.



There are a few conclusions that stand out in this visualizations. Firstly, it is easy to see that the Slip Jig has the most non-diatonic scale degrees of all the song styles. It is also easy to compare the ordering of the size of the intervals between song types. For example, almost all the song types have about the same percentage of ascending fourths, while the amount of ascending and descending thirds varies pretty substantially. Overall, the Slip Jig sticks out in the number of non-diatonic notes as well as the fewest descending seconds and most descending thirds.

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