Brian Slesinsky's Weblog

Saturday, 12 Jun 2010

How To explain Euler's identity using triangles and spirals

Saturday, 22 Aug 2009

Ear training, with links to neat YouTube videos

In an attempt to improve my musical skills, I've been practicing with Interval Ear Trainer a little bit every day. It's a web app that plays two notes, either sequentially or at the same time, and then you have to decide how far apart they are in pitch. (This is a common exercise for musicians.)

If you can recognize a melody then you can hear these intervals, though you probably can't name them. So it might seem like this is just a matter of learning some new names, but it's more like exercising a muscle you didn't know you had. Sometimes when practicing, I would start to think I was getting it, but then lose concentration and make silly mistakes. Low notes seem a bit easier for me than high notes, maybe as a result of my less-than-perfect hearing. Also, just like when listening to a song, the same interval can sound very different depending on what came before it. (Perhaps part of learning to recognize intervals is being able to ignore this effect?)

I've become reasonably good at recognizing intervals when the notes are played sequentially, so now I'm working on doing it when the notes are played at the same time, which is almost like starting over. It was a little frustrating until I hit on the scheme of practicing with only two intervals at a time, starting out with intervals that are spaced fairly far apart. (For example, I turned off everything except perfect fifth and octave.) After hearing the tone, I try to imagine the notes played separately, and that connects back to what I already know. Sometimes it takes a second or two for imagination to kick in: "It's not an octave so I know this must be a perfect fifth, but I'm not hearing it - oh, there it is." It's like I can almost feel the neurons connecting.

It's a fun exercise, in short stretches anyway. If you want to try this, a trick to help you get started is to associate each interval with a song you know. (You could use separate songs for ascending and descending intervals, but I just learned to mentally reverse the notes.) It's best to use songs you know well, but to get you started, here's what I use:

Incidentally, thinking of songs that you know with a particular interval and finding them on YouTube is a fine way to waste an hour or two! It would be fun to find out which songs other people use. My blog doesn't have comments, but if you use Twitter, I suggest posting the link to Twitter with #interval in your Tweet so that it will show up here.

(As an extra bonus tip, here's how to create a link that starts in the middle of any YouTube video: if the link looks like and you want it to start 2 minutes and 18 seconds in, then you add #t=2m18s to the end of the link.)

Update: I decided to write my own ear trainer applet. It lets you do interval training with random musical phrases. You can try it out here.

Sunday, 06 Apr 2008

Why can't Wall Street plan for emergencies?

When not following the election, I've found the latest financial crisis to be pretty interesting; how can so many smart people be collectively so stupid as to put the entire system at risk? I don't pretend to fully understand this stuff, but here are a few thoughts, from a spectator.

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Sunday, 30 Mar 2008

Capsule reviews of a few web comics I like

Maybe it's just that I haven't found the right web site yet, but discovering good web comics online seems a little harder than it ought to be. I went looking for new comics the other day, and found that lots of people make lists of their favorite comics but provide too little information: who wants to follow a blind link from a long list created by someone they don't know? On the other hand, there are a few websites that publish fairly serious critical articles about comics, but that's too much information when you're just looking for a new comic to read. And then there are the websites that review online and offline comics together, so you have to wade through stuff you can't read right now to get to the good stuff.

How is it possible that in the year 2008, a really good web comic review site hasn't spontaneously appeared out of the sea of obsession that is the Internet? It's a clear-cut case of market failure (or maybe just laziness on my part) that I could remain unaware of Girl Genius for several years after it started.

Until someone does start that website, I'll post a few reviews here and leave it to Google to get them to people who might find them useful:

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Saturday, 21 Jul 2007

Proposed Hanson Quarry Expansion

Someone sent me an email in response to my article on Permanente Creek. Hanson Permanente Cement is requesting approval for a plan to "include an additional 917 acres of mining and reclamation activity and extend the termination date by 25 years." There is a public meeting on Thursday, July 26th, and the public is invited to submit topics to be considered in the Environmental Impact Report by August 1. A volunteer group called AD-HOC is opposing the expansion.

Saturday, 07 Jul 2007

Posts I Liked

I don't know whether anyone has noticed it, so I'll mention it here: for a while now, I've been sharing links to blog posts and other web pages I liked in a widget at the bottom-right of each page on this website. You can see the whole list on this page, and there is also a feed.

Saturday, 02 Jun 2007

Chop it all up and start anywhere

It occurred to me while participating in a discussion about David Weinberger's Everything is Miscellaneous that the problems with what he calls the first order of order aren't entirely solved by putting information online, because they often have nothing to do with physical constraints of stores and libraries. They're actually about how we express ourselves.

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Friday, 23 Mar 2007

Here Comes More Video Spam

Apparently a recent anti-Hillary video on YouTube has gotten the professional political types worried about what's going to happen now that anyone can make a political commercial anonymously and for free. I'm thinking we went through this all before with text spam; the interest in this video shows that we're roughly at the Green Card lawyers phase of figuring out what this is all about. I don't have any answers but will speculate somewhat aimlessly about it anyway.

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Saturday, 27 Jan 2007

Lego Mindstorms NXT: First Impressions


I just got the new Lego Mindstorms and built the Tribot, after an impatient two weeks of waiting for it to arrive from Here are some observations after a couple days of tinkering.

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Friday, 05 Jan 2007

Weird Al Let Me Down

I bought Weird Al's latest album only to discover that I can't rip it into iTunes. This is because it uses a new standard called DualDisc, which acts like a CD on one side and a DVD on the other. The only problem is, the CD side doesn't conform to the technical standard for CD's and many CD players can't read them, apparently including iMacs. So beware, don't buy DualDiscs.

Tuesday, 26 Dec 2006

Go Search

A few months ago I started playing Go and, as usual when I become interested in something new, I spent a fair amount of time on the Internet reading more about it. Google works reasonably well, but because "go" is such a common word in English, search results tend to have a fair number of false positives. So, I used Google Co-Op to create a Go Search Engine that searches only Go-related websites:

The home page is here. Currently it searches about 40 Go-related websites; I added the most popular ones I could find until I got bored. Let me know if your favorite Go website isn't listed.

Saturday, 11 Mar 2006

Permanente Creek

In a few weeks I'll be moving to a cottage in Los Altos that's not far from Permanente Creek. This creek runs almost directly north. Most of the water is diverted by an artificial channel into Stevens Creek, but the creek itself goes north under 101, along the west side of the Google campus, and out to the bay. This part of the creek is man-made; originally it disappeared into the marshland. There's a trail that runs along the creek and construction is to begin this year on a pedestrian/bike bridge over 101.

Upstream, the creek flows from land owned by Hanson Permanente Cement (formerly Kaiser Cement). A rock quarry raises a lot of dust, some of that gets into the creek, and apparently there are ponds where the dust settles out, but that must have been insufficient because in 1999 the S.F. Bay Regional Water Quality Control Board ordered them to clean it up. I couldn't find anything explaining what happened since then.

The Kaiser Cement company was started by Henry J. Kaiser, who had a house in the hills next to Permanente creek. He also started Kaiser Permanente, one of the largest HMO's. Kaiser Permanente was named after the creek. The creek, in turn, was named "Permanente" by the Spanish because it was a reliable source of water that didn't dry up in the summer.

The creek has flooded many times before and probably will again. According to the map I saw, the property where I'll be living is outside the 100-year flood zone, but some people downstream aren't so lucky. There's a government project to do more about the flooding. Construction might begin in 2008.

[Update, July 2007: Permanente Creek does dry up in the summer nowadays. According to the June-July issue of Spinning Crank, the Permanente Creek Trail 101 overcrossing needs additional funding and its start date is still unknown. Hansen Permanente Cement is requesting government approval for an expansion of Hansen Quarry.]

Futher reading: