All about Digital Audio

Two brilliant videos, subtitled in many languages. Everything you always wanted to know about digital audio (and digital media in general) but were afraid to ask, by Red Hat's super geek Monty MontgomeryXiph.Org.
The first video "A Digital Media Primer for Geeks" presents the technical foundations of modern digital media via a half-hour firehose of information.
"The program offers a brief history of digital media, a quick summary of the sampling theorem, and myriad details of low level audio and video characterization and formatting. It's intended for budding geeks looking to get into video coding, as well as the technically curious who want to know more about the media they wrangle for work or play."

The second video explores multiple facets of digital audio signals and how they really behave in the real world.
"Demonstrations of sampling, quantization, bit-depth, and dither explore digital audio behavior on real audio equipment using both modern digital analysis and vintage analog bench equipment... just in case we can't trust those newfangled digital gizmos. You can also download the source code for each demo and try it all for yourself!"

A wonderful project and a great resource: some deep technical informations free for all, moreover explained very clearly.


Top 5 Sound Hacks Ever

UPDATED 30/10/2014

My favorite electronic sound hacks make use of acoustic illusions, the limits of our perception or the brilliant exploitation of technical equipment. It all happened before the 80s of the twentieth century.

1. Shepard Tone - 1964

A sound consisting of a superposition of sine waves separated by octaves. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower. Also known as the sonic barber's pole, the sonic Penrose stairs, the continuous Risset scale or Shepard–Risset glissando.

How does it sound?

How can you use it in your own compositions?
Csound/Csoundforlive: CircularPitch instrument in Rossing's Psychoacoustics Catalog.
Maxforlive: fp.Glissando device by eltnet. This great effect device uses Shepard-Risset audio paradox with signal in real time. See also M4L Pluggo for Live/Max Instrument/Shephard Tones.
SuperColliderRisset rhythm - eternal accelerando. The rhythmic version of the paradox by Risset.
Mac app and plugin: Endless Series - Oli Larkin.

Selected bibliography
Roger N. Shepard (1964). "Circularity in Judgements of Relative Pitch".
Diana Deutsch (1986). "A musical paradox".
Dodge, Jerse (1997). "Computer Music: Synthesis, Composition, and Performance".

2. Xenakis AM Grains - 1977

When Xenakis composed the music for the Diatope, La légende d'Eer (from Plato's Republic), he realized that in 1977 using granular synthesis with computers was actually more difficult than having invented it. So the composer took amplitude modulation (AM) to obtain some popular granular textures. One of the advantages of AM is that using just two signals or oscillators, or a simple tremolo with hacked modulator frequencies, we can create some partially rich signals, thanks to the sidebands generated when the modulator frequency moves to the audible range. For this reason, the resulting "grains" in this work are less noisy than the most famous grandchildren, and with a more complex spectrum.

How does it sound?

How can you use it in your own compositions?
Csound/Csoundforlive: a tremolo csd with the original Xenakis sample.
Green Oak Crystal: AM Plato Organ from my Crystal preset bank. Read carefully on how to install it on your computer.
Everything: experiment with an LFO applied to the VCA of your favorite synth, or with any tremolo effect. Some random frequency for the modulator will be appreciated.

Selected bibliography
James Harley (2002). "The Electroacoustic Music of Iannis Xenakis".
Giuliano Cantini (2006). "Tecniche di microcomposizione nella musica elettroacustica di Iannis Xenakis". This one was my thesis. An excerpt discussing this technique is available here.

3. Stockhausen Marimba Sound - 1955

Taking advantage of some intrinsic characteristics of filtering, you can edit envelopes and durations starting from a tiny impulse sound: a band-pass filter extends the signal transients (attack and decay), the smaller is the bandwidth with respect to the center frequency (filter Q). Varying the bandwidth and the center frequency you can play with noise and intonation. Stockhausen created and used this kind of sounds in the first electronic music masterpiece in history, Gesang der Jünglinge.

How does it sound?

How can you use it in your own compositions?
Csound/Csoundforlive: start with this basic patch.
Ableton Sampler: download for free my Karlheinz device (Ableton Pack). For more info check out this video.
Everything: start filtering a tiny impulse (you can get the smallest here). Filter type: Band Pass - Controls: Center Frequency and Q (or Reso). Done.

Selected bibliography
Riccardo Bianchini - Alessandro Cipriani (2008). "Virtual Sound".
Michael Manion. "From tape loops to midi: Karlheinz Stockhausen’s forty years of electronic music".

4. Schaeffer Cloche Coupée - 1948

One of the most famous accidental experiment in the history, that gave impetus to the musique concrète. After cutting (with a razor blade) the attack transient from a tape recording of a bell sound, Schaeffer noticed that most people could not identify the instrument that was playing. This experiment not only demonstrated the importance of the fast and noisy attack transient in our perception of sound, but also produced some nice instrument hybrids, obtained by joining attacks and stable parts of various sounds.

How does it sound?

How can you use it in your own compositions?
Any editor/sampler: split and slice audiofiles until you find a combination you like. Then map the sampler. Audacity and Edison can help you to batch edits over many samples at once.

Selected bibliography
Pierre Schaeffer (1966). "Traité des objets musicaux". This is the most beautiful and important book written on the art of sounds ever.
Pierre Couprie (2000). "Pierre Schaeffer".
Daniel Levitin (2011). "This is Your Brain on Music: Understanding a Human Obsession".

5. Risset's Arpeggio - 1969

Jean-Claude Risset's harmonic arpeggio is a beautiful drone-like sound, over which occurs a downward cascading arpeggio of a specified subset of the harmonic series. The instrument's timbre is similar to the sound produced by an overtone singer. Created by beating patterns that result from closely-spaced sinusoids, Risset describes the arpeggio gestures as "spectral scans".

How does it sound?

How can you use it in your own compositions?
Csound/Csoundforlive: see the terrific article by Bain in bibliography. I rarely read a technical article so clear and comprehensive.
UPDATE Chuck: read here and there.

Selected bibliography
Reginald Bain (2012). "Risset's Arpeggio. Composing Sound using Spectral Scans".
Jean-Claude Risset. "Computer Music: Why?".
Dodge, Jerse (1997). "Computer Music: Synthesis, Composition, and Performance".


Forbidden Planets - Music From the Pioneers of Electronic Sound - Various Artists
Schaeffer: L'Œuvre musicale - Pierre Schaeffer
Iannis Xenakis: Electronic Works 1 - Iannis Xenakis
Jean-Claude Risset - Jean-Claude Risset
Archives GRM: Le son en nombres - Various Artists
An Anthology of Noise & Electronic Music, Vol. 4 - Various Artists
New Electroacoustic Music from Paris - CCMIX