The result of a commission to produce a dance piece for children for the Rainforest Foundation. The piece involved spoken word, a children's choir, sound effects and backing involving a standard rock-band plus amongst other things; pan pipe samples and Spanish guitar. Hey Bulldozer is based on a two-bar musical quote (and I mean a quote, NOT a sample!) from the fade out of Hey Bulldog by The Beatles. This two-bar ostinato underpins the whole concern whilst other ostinato phrases build up on top, first four-bar, then eight-bar then finally sixteen-bar. The problem was, none of the pieces component parts - the choir, the band, the narrators etc. - seemed to be able to be at the same place at the same time! Genuine sound effects were promised from South America but these arrived only just in time for the final mix and then on a standard analogue cassette. The narration excerpts and pieces of choral annunciation were recorded in a dance studio in central London (complete with a very live acoustic and traffic noise) and arrived on un-edited quarter inch analogue tape recorded at 15 inches per second. The skeleton of the backing tracks were prepared as MIDI tracks and therefore existed only on floppy discs and the children's choir were rehearsed and waiting somewhere in deepest Surrey. It began to look as if personally lying in front of the bulldozers might be a simpler way of saving the rainforest!
Once the realisation set in that the whole project would have to be put together "collage" style, the first step involved making a gash mix from the original MIDI files and dubbing this onto a multi-track tape as a working cue track. The multi-track was then loaded in the back of the car along with an array of microphones, mixer, power amps and fold-back speakers and driven down to the choir. The children recorded several different "takes" whilst listening to the backing via several fold-back loudspeakers carefully set so that they were loud enough for the children to hear them but not so loud as to cause too much "spill" of this signal onto the final choir microphone signals.
Back at another recording studio a week later, after the final tweaks to the MIDI sequencer data and samples were complete, the complete vocals track was formed by selecting the best bits from the various "takes". The narrated speech and choral speaking excerpts were then carefully edited and "topped and tailed" using a digital audio hard disk editing system and spun-in to a track on the multi-track by hand (or do I mean by mouse?). The two acoustic guitar tracks were then added, then the electric guitar track and then a backwards electric guitar which involved turning the multi-track tape over on the deck and having the guitarist play along to the other tracks backwards (something you can only do with an analogue multi-track machine!) And all that was left was to add the sound effects which involved a combination of real jungle sounds (from cassette - arrrgh!) and library FX. Oh and the mix down, 16 tracks of MIDI, four guitars, four stereo pairs of choirs, 2 of narration, 4 of sound effects. Not having the budget for a studio with fader automation, it took me six goes but we got it in the end.
It still intrigues me when I listen to the finished song that the children who say, "Leave the forest alone," and the children who sing, "Don't let them bulldoze the rainforest away" immediately afterwards are not only the not the same children but were recorded twenty miles and a month apart. It's a tribute to modern parametric equalisers, noise gates and digital reverberation equipment that the choir, recorded direct to master tape with spaced omni microphones in stereo doesn't sound too different from the chorus who were recorded in a noisy London location in mono onto analogue quarter-inch tape with different microphones.
Despite its tortured genesis, I'm proud of this track. It starts with a an eerie prediction from an Indian chief which still sends a shiver down my back.....
There is so much smoke, all the animals are being killed, the rivers too. My spirit is warning me that when the forest is all destroyed there will be no shade, there will be very strong winds, the sun will get very hot and it will be difficult to breathe. Then everybody will die, not just the Indians - everybody will die. I am warning you - leave the forest alone.
Hey Bulldozer received several performances during the summer of 1991 and has been performed several times since in different versions. There are a number of commercial recordings available.
Track 52 - Birdsong
Birdsong illustrates how sounds may be cut up and re-used (the term "brassage" is sometimes used) in digital editing software. Here the technique has been exploited to produce a musical composition based on the minimalist technique of taking tiny sound "bites" and building them into larger structures. In this case, the building "bricks" are taken from a recording of rennaissance choral music. These are layered, reversed and mixed to produce the final collage of sound. The title is from the book by Sebastian Faulks.
Track 53 - Classical, crossed-pair stereo recording. This file, and the following downloadable MP3 encoded file, contain a recording of Handel's "Messiah" (made by Perfect Pitch Music Productions - there's no piracy on these pages!). This track was recorded using the classical, crossed, cardioid microphone-pair technique. When you listen to this music on a two-channel stereo audio system, a sound "image" is spread out in the space between the two loudspeakers. And the result is really very pleasing. However listen carefully to the reverberation and to the precise position of each instrumental and vocal sound-component. The reverberation isn't completely "aligned" with the direct sound. And individual instruments are not as precise as when you listen in real life. Can stereo be better than this?
Yes it can: Track 54 is Francinstien processed. Note the integration of live and reverberant sound; as well as the pin-point positioning of the instruments. Now imagine what this would sound like in your hi-fi system and not on your computer!
Track 54 - Track 53, FRANCINSTIEN processed.
Track 55 - Stand-In for an Echo
As far as I know, there exists no strong intellectual link between the minimalist movement and the hard-boiled, pulp novels and detective films of the nineteen-thirties and forties. Perhaps it is their common, unflinching lack of emotion - or simply their distinctive Americanism -which ties them so closely together in my own mind. Whatever the reason, I've taken this opportunity to re-write history and re-score some of my favourite moments from a few classic "Noir" films.
Technically, the music incorporates the discrete phasing technique which Steve Reich introduced in Clapping Music in 1972. All four instrumental parts are derived from the set of patterns played by piano 1. Piano 2 copies these patterns but drops on quaver-beat every 30 quavers, the flute drops a quaver every 20 quavers and the marimba drops a quaver every 9 quavers. The process is extended to incorporate several "tacit" bars before any instrument starts. In other words, the phasing has "already begun" before the music starts. Over the instruments are superimposed "sound-bites" taken from the films of books by Dashiell Hammett and Raymond Chandler. These, monaural, sound sources are treated by means of a spatial sound processor to appear outside of the area bounded by the loudspeakers and even behind the listening position - without the use of extra loudspeakers.
The title is taken from one a jotting in one of Chandler's note-books, "I called out and no-one answered, not even a stand-in for an echo."
More tracks to demonstrate the psychology of auditory perception hidden_tone: This track demonstrates the phenomenon of "hidden bass". The first few seconds is a synthesised waveform composed of the 2nd, 3rd, 4th and 5th harmonics of a 440Hz fundamental; except that no fundamental is present! There follow several seconds of a 440Hz sinewave. And the track finishes with a repeat of the first waveform; harmonics only, no fundamental. Note how the perceived pitch of the sound doesn't change, the ear effectively "fills in" the missing fundamental.
hidden_bass: Similar to the previous track, but with a fundamental of 100Hz.
phase_deaf: This track consists of a 261 Hz tone with 50% third harmonic (783 Hz). In the first 5 seconds, the third harmonic has a zero phase relationship with the fundamental: in the second half the third harmonic has a 90 degree offset. Notice that the timbre is exactly the same. The ear is phase-deaf to this type of steady state sound; hence the reason why tone controls which affect phase response are tolerable in audio.
triangle: triangular waveform at 261 Hz fundamental.
inc_mod_index: Demonstrates the effect of increasing modulation index. The 440Hz tone is modulated by a modulation frequency of 330Hz with an increasing modulation depth. Note the brightening of the tone as modulation depth increases.
bell_1: A reversed and edited version of inc_mod_index; showing how a gradually decaying modulation index (coupled with the appropriate amplitude envelope) can be used to generate a sound wherein the harmonic complexity decays throughout the tone. The resulting composite tone is very bell-like.
bell_2: Delay effect added to a (slightly attenuated) bell_1.wav, to add realism to the bell sound.
bell_3: Bell_2.wav, used as a sample to generate a Westminster chime.
hammond: The first part of this track is a simple additive synthesis of squared sinewaves in the following proportions: fundamental x 100%, 2nd harmonic x 56%, 4th harmonic x 35%, 6th harmonic x 21% and 8th harmonic x 32%. Already, the sound has the characteristics of a Hammond organ. The classic tone-wheel Hammond organs produced reasonably high purity sinewaves; using squred sinewaves helps add the distortion which the amplifiers and keying circuits introduce. After 3 seconds a simple chorus effect is added to give the sound the simulation of the Hammond organ sound amplified and passed through a Leslie loudspeaker.
Unfortunately not all vocal performances can be captured in the hallowed halls of La Scala, Milan. So how might we capture the particular characteristic of an individual performance space? This is the aim of convolutional reverb.
There exists the interesting possibility that, if a very short pulse (known as an impulse function) is played over loudspeakers in an acoustic environment: and the resulting reflection pattern recorded with microphones and stored in a digital filter, that any signal - passed through the resulting filter - would assume the reverberation of the original performance space. Truly one could sing in La Scala! The next two tracks are intended to demonstrate the principle of convolutional reverberation.
reverb_signature: This is a recording of a short impulse, recorded in a church.
convolved_reverb: In this track, reverb_signature.wav is used as the impulse response and convolved with a short organ tone. The result is the reverb signature of the church "imprinted" on the organ tone.
All tracks on Music Engineering CD disk and this website are © Richard Brice 2001. All rights reserved.
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