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I am a research fellow, conducting research into automatic analysis of bird sounds using machine learning.
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Older things: Evolutionary sound · MCLD software · Sponsored haircut · StepMania · Oddmusic · Knots · Tetrastar fractal generator · Cipher cracking · CV · Emancipation fanzine


Wow, look what came in the post today: the latest release of Alan Jenkins' FREE SURF MUSIC. In fact I got all four albums as part of his kickstarter pledge (watch that video).


This latest one (#4) is one track of 47 minutes and one almost as long. It's a tuneful yet avant-garde surf landscape. Love the way it's experimental yet with tunes that I was singing along to even on first listen.

Frankly I don't understand why there aren't more people making this kind of music. Broad-minded surf instrumentals which lapse in and out of surreal abstraction! ISN'T IT OBVIOUS? COME ON PEOPLE

music · Permalink / Comment

Here's an audio phenomenon you should know about: Schroeder-phase complexes.

These are harmonic series which are designed so that their amplitude envelope is maximally flat. When you synthesise a harmonic series of partials, you know what frequencies you should use for the component sinewaves: F, 2F, 3F, 4F, etc. But what phase should you use?

Often we stick with a simple default such as every partial starts with zero phase. There's an issue with that, though, which can lead to issues in perceptual tests: the amplitude envelope, within one pitch period, is quite bumpy, because there are moments when the component phases all line up to produce strong amplitude. Sometimes this bumpiness leads to experimental confounds.

One thing you could do to work around this is use random phases, but adding this extra randomness into an experiment is usually not that desirable.

In 1970 Schroeder published a formula for choosing the phases so that the resulting waveform has a minimal crest factor, i.e. no big amplitude peaks. The formula is pretty simple but my blog doesn't render equations yet so see e.g. this paper.

Let me prove this to you directly: here I've synthesised the same harmonic sound with five different choices of phase. The top row, "sine-phase" and "cosine-phase" correspond to two versions of the default phase-aligned choice, and look how spiky they are:


In the middle is random phase, and at the bottom are two plots from Schroeder-phase. Please note that the y-axis has different scales in each plot - the waveforms each have the same energy, and the same Fourier-transform magnitudes, despite looking very different!

The reason that there are TWO Schroeder plots is because we have an option to flip the sign (time-reverse the waveform) while preserving the waveform characteristics. The shorthand label that people sometimes use is that one of these is "Schroeder-plus" and one is "Schroeder-minus".

BUT WAIT there's one weird thing I haven't shown you yet, and it pops out when you listen to the examples. These stimuli can be used to find frequency thresholds - at low frequency we can tell the difference, but at high frequency they sound identical. And the weirdest thing is when you listen to them at very low frequencies, they don't sound like static harmonic complexes at all (evenr though that's definitely how we generated them), they sound like otherworldly down- or up-chirps.

Listen to this audio file where I play a plus and a minus, at different frequencies. First at 300 Hz, then at 65 Hz, then 16 Hz, then 2 Hz. At first you'll hear two essentially identical tones, but then the differences become noticeable, and then overwhelming:

Download the wave file

It's a nice demonstration of the fact that any periodic signal can be conceived as a sum of stationary sinusoids - as in Fourier analysis. Here we synthesised a chirpy nonstationary-sounding (but periodic) signal, starting from scratch from the sinusoids.

My implementation is here as SuperCollider code, inspired by this paper: Phase effects on the perceived elevation of complex tones.

sound · 1 comment

If you live or work in Tower Hamlets then please give them feedback on the "Local Plan" they're developing. It's a plan for the next 10-15 years of development in the borough.

So... what's the point of a Local Plan? In practice, it's a document which gives councils/developers/mayors the written "excuses" they need in order to do things or to block things. So the content of the Local Plan will indeed shape what happens.

Some comments from me:

Also some things I found while reading around this topic:

But anyway, like I said, give them feedback on the Local Plan.

politics · Permalink / Comment

Just finished this really useful little book: "Medina in Birmingham, Najaf in Brent: Inside British Islam" by Innes Bowen. It could well be subtitled "An executive summary of Islam in Britain", because that's exactly what it feels like - a brief, breezy and dispassionate summary of the main Muslim groups in the UK, what they believe, how they interact with the world, etc.

Very handy reading, if you're a non-Muslim British person like me who might be wondering: the Muslims in my neighbourhood, are they sunni or shia? Does it matter? How do they relate to the various Muslim groups that are making the news these days? Which ones dress in special ways, and how significant is it? - All those naive questions that you can't just come out and ask.

All kinds of interesting stuff comes up while answering these questions. For example I learnt about the Tablighi Jamaat and why they wanted to build the "mega-mosque" that has been back and forth in the news trying to get planning permission. I learnt which groups have a voice in the Muslim Council of Britain. And even though the book doesn't spend much time on women's issues, it gives lots of titbits about different groups' conventions on veiling, staying in the house, marriage, and mosque provision - so it gives me some "local" insight to complement this other reading on veiling practices.

As in that other book, one thing that might surprise you is that some seemingly "traditional" things (like clothing practices) are borne of quite modern movements within Islam; really, you realise that "traditional" vs "modern" is not a particuarly helpful way to distinguish different strands of Islam practiced in Britain today.

books · Permalink / Comment

Kale and rosemary flatbread. What I particularly like about this flatbread is that the kale baked in the oven goes crispy like fried seaweed. I had it as a main course with a bit of rocket and some manchego cheese. It could also be a good accompaniment, maybe an accompaniment to something meaty.

Serves 2. It's derived from a recipe from "Crumb" by Roby Tandoh.

Combine the flour, salt, pepper and yeast in a large bowl. Make a well in the middle and add the warm water. Mix with a fork, then when that gets difficult add 1 tbsp of the olive oil and rosemary, and mix with one hand.

Knead it for 10 minutes. You might be able to do this in the bowl or it might be easier to tip it out onto a clean surface. You might need to sprinkle a bit more flour on. It should become elastic and less sticky.

Now cover the dough and let it rise for 30-60 minutes in a warm place. Meanwhile, blanche the kale: bring a pan of water to the boil and plunge the kale in. Boil it quickly for 1 minute, then immediately drain it and run cold water over it to stop it from cooking any further. Now you need to get it as dry as you can, firstly by draining it then by pressing it gently.

Knead just under half of the kale into the risen dough. It'll be a little tricky, due to the residual moisture on the leaves, but there's no need to worry about it being perfect.

Preheat a fan oven to 170C. Using a rolling pin and a floured surface, roll out the dough and then roll/hand-stretch it into a kind of A4 shape, quite thin, and put it onto a lightly floured baking tray. Put the remaining kale over the top, pressing it down a bit so that it'll stick in. Drizzle plenty of olive oil over the top and bake for 20 minutes.

recipes · Permalink / Comment

David Cameron wrote an article today saying that knocking down poor people's homes is how to make their lives better. ("David Cameron vows to 'blitz' poverty by demolishing UK's worst sink estates").

There's a short version of my response to this: go and read Anne Power who's studied housing and regeneration a lot, and has concrete recommendations for the best way to handle all this stuff. Read this article: "Housing and sustainability: demolition or refurbishment?"

I was undecided about all this stuff in 2014 when I went to see the Carpenters Estate protests. If you're not involved, it sort of sounds like a good idea. "Ooh those scary estates. If we knock them down and replace them with shinier ones, that's the neatest way to fix the situation up, and the residents can come back and live in them so they won't be any worse off."

But then you go down to the estates and meet people, and you read about how these regenerations happen in reality, and you realise it's not as neat as that. Firstly, in modern times regeneration usually involves selling off a fraction of the estate for private development, and the community doesn't really get to be rehoused back together, many get scattered to random locations over which they have no choice. Community cohesion is lost, i.e. part of the social fabric that keeps everyone safe. Secondly, demolition has unhelpful side-effects on the area around it (house prices, antisocial stuff, disrepair, local services leaving). Thirdly, there are alternatives to demolition (renovation, infill building) which avoid many of these downsides, are more sustainable, and are good for the local economy because local small-scale builders can do them.

Cameron said three out of four rioters in 2011 came from sink estates. "The riots of 2011 didn’t emerge from within terraced streets or low-rise apartment buildings. The rioters came overwhelmingly from these postwar estates. That’s not a coincidence," he wrote.

David Cameron, your logical fallacy is: False Cause. The people he's talking about are poor and disenfranchised, and that's the common cause of both things. It's the cause of living in the less popular estates, and it's an important cause of the rioting. It's not the shape of the buildings which caused the riots!

The current UK government is acting from a position of strength, and they are really taking their opportunity to make bold moves in the directions they want. Putting money into improving housing can be a good thing - the biggest risk I see is that this initiative will end up pushing poor people out of the way and fragmenting their communities. We can do it better. Read this article: "Housing and sustainability: demolition or refurbishment?"

politics · Permalink / Comment

Poached thai-style sea bass - a handy everyday recipe, easy to do, healthy and fresh, whenever you see a nice piece of sea bass in the shop. It takes less than ten minutes. All of the flavourings are optional really but most of them can be kept in your store cupboard.

These amounts are to serve one.

Boil a kettle.

Meanwhile chop things up: the spring onions into ~1mm slices, the chilli into ~1mm slices, the root ginger into fine slices, and chop the parsley. Don't chop the lemongrass, but bruise it (bash it with the heel of the knife a bit). Don't chop the lime leaves.

Put all the flavourings (not the coriander/parsley) into a pan with a small-soup-portion of boiled water and bring it to the boil. Add the noodles, then add the seabass so it sits on top of them (it should still be submerged though). No need to stir anything.

Turn the heat right down and put a lid on. Let it poach for about 5 minutes.

At the end, ladle the whole lot into a soup dish, ideally keeping the fish in one piece sitting on top. Sprinkle the coriander/parsley on.

recipes · Permalink / Comment

Lunchtime showdown: three different tins of mushy peas!

Mushy peas line-up

All served up with a bit of black pudding.

Mushy peas throw-down

The verdict:

Sainsbury's mushy peas are not very nice - there's a kind of minty flavour (mint is not in the ingredients) which tastes like it's masking something.

Harry Ramsden's are nice - chip-shop flavour, with a decent hint of savoury flavour.

Batchelors mushy peas are pretty similar to Harry Ramsden's, but with not so much of the savoury depth. They're fine, but just short of the chip-shop flavour I'm looking for.

food · Permalink / Comment

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