February is over, and that means RPM 2013 is, too. I only managed three tracks, but at least I did spend some good time thinking about sound.

My tracks are here.

This is track #2 for my RPM 2013 Challenge sound pieces.

It comes with a video, created at the same time.

Headphones are recommended.

Ten balls move linearly at various constant speeds, bouncing off the sides. Every triangle formed by these balls is drawn, the color determined by how equilateral the triangle is (redder = more equilateral). A sound event is generated for each triangle, twice per frame, determined by the size, location and equilaterality (?) of the triangle.

Made with Csound (audio) and processing (video).

You can see it bigger if you click through to Vimeo.

triangular composition from Matthew Conroy on Vimeo.

Now that the quarter is over, I took a moment to put all my tracks from the 2011 RPM Challenge up on the site. They are all here. Let me know if you'd like a link to a zip file so you can download them all at once.

Track six is up at RPM Challenge 2011. This one is a recording of four prepared music boxes. I prepared them by taking out the guts, removing the plate with the plucky bits, and turning it over, so high pitched notes are now low pitched, and vice versa. The plucky bits are made so that bending in the usual direction is easier than the reverse direction, so in this track you hear the plucky bits putting up a fight. Also, I use binder clips to hold the plate to the rest of the mechanism (since the holes for the screws which normally hold it in place are offset, and do not align when the plate is inverted). The binder clips resonate in their own way with the sound from the music box, and add to the general cacophony.

Track five is up at RPM 2011. It is called "Pride and Enjoyment" from the sample I used as the source audio. I used Csound to generate many layers of rhythms made from sub-samples of one main sample. I threw some ring modulation in the middle to make things more crunchy.

Track four is up at RPM Challenge 2011. It is called "Finger Rodeo".

It was recorded on a dare. I should take more dares.

Another track at RPM Challenge 2011.

This one uses linear transformations to manipulate the audio spectrum from one instant to the next. The result would be asymptotically static, so I added injections of coherent sound periodically (every second). Noisy, but with a nice feel, I think.

Two new tracks up at the RPM 2011 Challenge.

One is straight noise created from the first 100,000 zeros of the Riemann Zeta Function.

Another is one result of an idea I've been using for a while. It is a granular synthesis kind of thing, where the amplitudes of a bunch of grains of fixed frequencies are determined by a quasi-cellular automata. The idea is that the next instant (0.01 seconds) of sound is determined by the current instant of sound.

I hope to do some non-Csound things this month, but time will tell.

I added two more sound files to my page of integer sequence noise. The new sequences are the palindromic numbers (like 121, 32423, etc.) and the set of values taken on by sigma, the sum of divisors function (1,3,4,6,7,8,12,13,14, etc.). The first doesn't sound very interesting, as palindromic numbers are a bit too rare and regular, but the second one is quite noisy. There is a bit of a peak at 44100/6=7350 hz, since multiples of 6 tend to be values of the sum of divisors function, but it's pretty uniformly noisy.

I finally got around to creating a page with my noise from integer sequences.

Put your headphones on and check it out and let me know what you think (or hear), and if you have suggestions for other sequences.