• Guitar

    Guitar

  • Audio Production & Sound Design

    Audio Production & Sound Design

Music

Music

Current, upcoming and legacy composition projects.
Read More
Events

Events

Gigs, performances, lectures and events.
Read More
Sound

Sound

Audio production, sound design, live electronics and engineering
Read More
Words

Words

Music publications, articles, papers, lessons and whatnot.
Read More

Latest News

Contact

Spiegel Im Spiegel on a Postcard

The most succinct analysis I can make of Arvo Pärt’s Spiegel Im Spiegel (a stunning and elegant work). Listen here: https://open.spotify.com/track/3rlqTqUOzu0zDwQFJe44gk

Spiegel Analysis

Palindromic scales and their modal groups

I’ve had this insight about palindromic scales, modes, modal groups, and the Euclidean (and sometimes maximally even) distributions of 7 notes in a one octave scale. This is what it looks like in my head. I really like that the ‘central’ scale of a group is not the traditional figurehead (Ionian, melodic minor etc.) but the palindromic parent. Nice to see the patterns emerge diagrammatically, and I will aim to use Melodic Phrygian and its modes in composing/improvising!

Palindromic scales

 

Pendulum Music

Translation of pendulum waves to music using a simple pitch translation system on a 5-limit Yo scale. Watch the right hand edge and all will make sense! This little experiment turned out so well, I think it deserves a whole project. My head and ears are spinning.

Bloodlines on Radio 4 Midweek

A real pleasure to appear with my sister Alex to talk about the Bloodlines project (and data sonification in general) on BBC Radio 4’s Midweek on Wednesday 28th October hosted by the quite brilliant Libby Purves. Fellow guests included the delightful and inspirational Peggy Seeger and Amati’s James Buchanan.

Available here:

Sonic Circles

The next in the series of Hidden Music data sonification works. Data sonification is a long term interest/project/passion of mine, which involves the systematic translation of ‘non-musical’ data into music.

Here I’ve taken Kandinsky’s beautiful 1926 painting Several Circles and translated it systematically into sound. Colour and vertical position are translated into timbre and pitch respectively, as the red cursor scans the image horizontally.

Whether Kandinsky was a synaesthete or not is disputed, but his fusion of music and visual art metaphor, working process and concept is well documented. From the link:

“Our response to his work should mirror our appreciation of music and should come from within, not from its likenesses to the visible world: “Colour is the keyboard. The eye is the hammer. The soul is the piano with its many strings.”
Kandinsky achieved pure abstraction by replacing the castles and hilltop towers of his early landscapes with stabs of paint or, as he saw them, musical notes and chords that would visually “sing” together. In this way, his swirling compositions were painted with polyphonic swathes of warm, high-pitched yellow that he might balance with a patch of cold, sonorous blue or a silent, black void.”

Thanks as ever to Anna Tanczos for the visuals.

 

 

Distant Harmony

Here’s the first in a long series of data sonification experiments. This Hidden Music series is a long term interest/project/passion of mine, which involves the systematic translation of ‘non-musical’ data into music. Here’s a simple example, the orbital periods of the planets of the solar system translated into pitch and rhythm. The rhythms are simply created by speeding up the actual orbital periods by 25 octaves (doubling the speed 25 times), and the pitches are created by transposing them up 37 octaves. I haven’t quantized pitch or rhythm, so its both microtonal to the nearest cent  (100th of a semitone) and microtemporal (to the nearest millisecond), but I hear a clockwork beauty in this irrational/chaotic collection of ratios nonetheless. Stay tuned for some even more distant harmony from some ex-planets. I recommend a sub-bass speaker to really feel Uranus and Neptune’s drones. Thanks to Rob Scott for his space science brain, and my long term partner-in-nerd Anna Tanczos for the visuals.

 

IGRC 2016 Call for Papers

The next international conference of the International Guitar Research Centre has been announced. It will take place 18th to 23rd March 2016. The call for papers, keynote speakers and headline concert artists can be found here. The deadline for proposals is midnight GMT on Friday 9th October 2015.

The IGRC has no stylistic or conceptual prejudice, if you are doing work that is innovative, creative and related to the guitar, we are interested. For further info

Harmonic Series vs. 12-Tone Equal Temperament

It’s hard (for me at least) to start talking about any aspect of musical theory without talking for an hour or writing several thousand words and/or producing many diagrams. So I’m going to try and just provide some vignette posts, little moments of insight in a hugely complex field of study.
Here let’s look at the harmonic series (the pitches that emerge by multiplying a frequency by the set of integers (1,2,3,4 …) and its relationship to 12-tone equal temperament (the ‘standard’ division of the octave into 12 equal divisions).
The following diagram courtesy of the incredible programmer Dean McNamee (and Mathematica) shows how the pitches generated through the harmonic series differ from 12-tone equal temperament.

harmonic-distance-1-20

 

The X-axis names the harmonic number (ending at the 20th harmonic) and the Y-axis is the deviation from the nearest even-tempered note (where for example -0.2 is 20% of a semitone flatter than equal temperament). If you look carefully, you’ll see that the fundamental and all the octave equivalents (harmonic numbers 1,2,4,8, 16 etc.) align perfectly with the even-tempered equivalents. In fact these powers of 2 are the only point where the harmonic series meets up (exactly) with 12-TET. These points are circled in red below.

Annotated Harmonic series vs 12-TET

The ‘non-octave’ harmonics are indicated with different coloured arrows (showing in which way they differ from equal temperament). The 3rd harmonic (indicated in orange) is about 2 cents (a mere 2% of a semitone) sharper than the equal tempered equivalent (a perfect 5th), and so of course are its octave equivalents the 6th, 12th, 24th etc. The 9th harmonic is about 4 cents sharper (as it is ‘affected’ by two 3rd harmonics), and is indicated with 2 orange arrows. This ‘stacking’ (and unstacking) of the 3rd harmonic is what is used to create the Pythagorean scale, also known as a 3-limit scale, since we only allow the 3rd (and 2nd) harmonic as tools to reach musical notes.

The 5th harmonic is significantly flatter than the 12-TET equivalent (and the cause of the many historical temperaments that have emerged in polyphonic music. The 10th harmonic has the same ≈14 cents discrepancy. The 15th ends up about being 12 cents flatter, since 15 = 3*5, it uses the 3rd harmonic (which makes it ≈2 cents sharper than 12-TET) and the 5th harmonic (≈14 cents flatter) resulting in an overall drop of about 12 cents (note the contrary orange and yellow arrows). Incidentally, the use of the 3rd and 5th harmonic (together with the trivial 2nd harmonic), creates the 5-limit system of tuning, with its extensive and beautiful use in Hindustani music.

You’ll see that the other prime-numbered harmonics get their own coloured arrows (7th=green, 11th = blue, 13th = purple etc.). The 11th is about as far from 12-TET that is possible, which is why Harry Partch stops there in his 11-limit 43-note universe. Since the primes never end so the harmonic pathways of tuning are (theoretically) endless.

Another way to see the relationship between the harmonic series and 12-TET is to visualise the harmonics resting at points on an infinitely expanding spiral. Each sweep of the spiral represents an octave, and the 12 equally spaced slices of the octave pizza represent each 12-tone slice. This has the advantage of indicating where in the octave each harmonic lies, as well as the octave relationships between sets of harmonics (e.g. between the 3rd ,6th, 12th and 24th harmonics  etc.). Here’s a beautiful rendering by Skye Lofander (whose website musicpatterns.dk has many awesome visualitions of musical concepts and is highly recommended).

Ligedeling vs naturtoner

You’ll notice that the harmonics get closer and closer together, and essentially ‘sweep’ through the 12-TET discrepancy in an ever (but never completely) flattening upward slope. Here’s Dean’s rendering which shows the same phenomenon emerging with the first 500 harmonics:

harmonic-distance-1-500

 

So along the way the 12-TET and harmonic series will get ‘close enough’ most certainly for human perception (which is a couple of cents on a good day) and acoustic instruments (which waver considerably in temperature and human execution). Even a slight head-turn will invoke enough doppler shift to make fractions of a cent meaningless in real terms.

So which is ‘better’ 12-TET or tuning derived from the harmonic series (also known as just (i.e. ‘true’) intonation)? And what incantation of the harmonic series is more ‘pure’? Is 4 jumps up the 3rd harmonic more ‘natural’ than one jump up the 5th harmonic? They both roughly approximate the major 3rd (the first a ‘Pythagorean third’ ≈8 cents sharper than 12-TET, the second a ‘just 3rd’ at ≈14 cents flatter). Some have attempted a measure of harmonicity (see Vals and Monzos), but its relationship to subjective experience is sketchy at best. Can one think of 12-TET as existing way, way up the harmonic series (so still harmonic), is it a ‘good enough fit’, or wholly incompatible with the harmonic series? What’s inate and wha’t encultered? Why 12 equal divisions and why not some other number?

EDOs

Just intonation enthusiasts can get heated about its superiority to 12-TET, but there is no doubt that the limiting of notes to 12, close-to, or exactly evenly-spaced has led to the creation of countless, otherwise impossible, musical creations and activities.

The best answer is that they are different, and both available to every composer, get over it, embrace and enjoy.

P.S. this was 3 times longer than planned. Apologies.

John Williams (Candle)Light on the Edge

On Saturday 6th June 2015, I’ll be performing with John Williams, Gary Ryan and friends at the beautiful Shakespeare Globe in London. Among other works, we’ll be performing Phillip Houghton’s sumptuous Light on the Edge by candlelight. I’ll be providing electronics (courtesy of Ableton and one of my many MIDI controllers) and it should be rather magical, unless of course I accidentally play Chloe’s playlist of Wheels on the Bus and other hi-energy toddler classics.

Click the pretty picture for info and tickets.

Pretty

 

A Painful Lesson in Sampling Rates

Van SamplenAn audio sampling rate is the frequency at which an audio signal has been captured. You can think of it like the frame rate in movies, capturing a series of photographs from which a seemingly smooth film can be generated. The sampling rate for CDs is 44.1kHz (that’s 44,100 samples per second between you and me), but other sampling rates exist 48kHz, 96Kz, 192Khz etc. It’s a contentious issue – beyond the scope of this wee post – about how high is high enough and why that may be the case but it is vital to ensure that whatever rate an audio file is recorded at, that’s the rate that it should be played back (unless you want the speed and pitch of the original recording to change of course). Essentially its like a record player and a record. A record may have been produced at 33rpm, and to ensure you hear the intended pitch and speed the record player has to spin at the same speed. Simple.

So what happens if we spin a record (or playback a digital audio file) at a higher rate than it was recorded? Well it’s pitch becomes higher and its speed increases. Play back at a slower rate and its lower in pitch and, well, slower.

What’s more, if we play a file (or record) at twice its intended rate (a 44.1kHz file at 88.2kHz), its duration is halved (of course) and its pitch goes up an octave. In contrast, a file played back at half of its recorded rate drops an octave (you can hear this used musically in loop pedals).

An octave (derived from halving or doubling a frequency) has a kind of musical equivalence. (It’s called the Law of Octave Equivalence no less), but what of other frequency relationships? Here things get a bit complicated.  Our experience of pitch is logarithmic, so that the multiplication of a frequency produces a particular musical interval. Double a frequency it goes up an octave, halve it it goes down an octave, multiply by  ≈1.059463 and the pitch goes up one (equal-tempered) semitone. This catchy number is actually the 12th root of 2, which makes sense if you think about it. Multiply it by itself 12 times and it reaches 2, because there are 12 ‘equal’ jumps between in each octave in the 12-tone equal-tempered system.

To help us understand this, let’s imagine an octave as a physical vertical object, then we can slice it into a number of equal slices (say a tower block with a number of equal storeys). Again, I say ‘equal’ because each slice is the same musical interval but that in fact means that it is the same multiplication every time (that’s the whole logarithmic thing). The convention is to divide the octave into 1200 cents. Why are they called cents if there are 1200 of them? It makes no cents HAHA – well because often the octave is divided in 12 big slices (known as semitones or half steps) and each of them has 100 cents. So 100 cents is a semitone (in the US half-step), 200 cents is a tone (whole-step), 700 cents is a perfect 5th and so on.

So how can we calculate the resulting musical interval from a dispcrepancy in sampling rates?

We use this equation.

cents = 1200 × log2 (f2 / f1)

That’s it.

So, imagine an audio file was recorded at 44.1kHz (f1) and played back at 48kHz (f2), the cents difference would be

1200 × log2 (48000 / 44100)

This comes to ≈146.7 cents, which is just shy of one and a half semitones. A no-person’s land in most musical situations, and if you were trying to play along on the guitar you could go up one fret (one semitone) and still be a quarter tone flat, but 2 frets would be over a quarter tone sharp. Most ears forgive a few cents here and there, and a keen musician can bend into a few cents more but a 46.7 (or 53.2) cent differential is about as cold sweat nightmare of a musical situation imaginable. A bass player would face the same problems, and a keyboardist would have to resort to Herbie Hancock style pitch bends, or embark on a desperate hunt for the operating manual to readjust the tuning reference. Failing that they could run away at just the right speed to allow the doppler effect to drop the pitch.

Would you like to know what it sounds and feels like? Just ask Van Halen and their audience, who suffered this exact ordeal when a backing track (or keyboard triggered sample) recorded at 44.1kHz played back at 48kHz during a live performance of ‘Jump’ – not the most obscure of their tunes. Eddie desperately tries to adjust by shifting frets but is cursed by the mathematics.

Funny or painful, you decide. The jump that EVH desperately offers at 2:02 is fraught with all the tragedy of the human condition. But at the very least, this remains an important lesson in the importance of sampling rates, logarithmic scales and their relation to musical intervals. Thanks Van Halen!

Menu Title