Imaginary music (PRELIMINARY ENGLISH VERSION)

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Chapter 12 : The musical creation process

The chain of creation

Addressing either the composition or the performance, the creation consists in using one's freedom to produce the music.

The chain of the processes which contribute in the musical creation is more or less long,  but  the departure and the arrival points are always similar :

at the point of departure, the music is in the mind of the composer, and can be imagined through formants (melodies, sounds, movements, etc.) ;

at the point of arrival, the music can be perceived by other human beings only realized by waves of vibration of the air.

Let us take the case of a complex chain: the composer writes on scores and edit them several times; the thought drives the writing and the writing drives the thought. Then the score is reproduced, then given to an interpreter or to a symphony orchestra. After several rehearsals, the piece is executed in a studio to obtain a multitrack recording. This recording is mixed to produce a master-disk. Disks are burned and sold. The music-loving buyer can then adjust his hi-fi system and listen to and listen again.

The simplest case is the improviser who plays in front of his public.

A musical creator thus drives one or several processes in the chain, which includes both moments when the music progresses in the time and moments when it remains stored, in a written or recorded way.

To steer a process, it is necessary to perceive its result, to adapt consciously or unconsciously its control to obtain what is wanted. So the instrumentalist or the singer has to listen to himself, the editor listens again to his tapes, the writer of scores reads again, etc..

This perception in return, or feedback, is essential for the process of creation.

Music and feedback

What is feedback?

 

The feed-back is a fundamental concept of the Theory of Systems.

The feedback consists in reintroducing the result of a process to control this process itself. We also speak of  "loop" of the process on itself.

feedback

Figure 1 : diagram of a process with feedback

 

The effect of the feedback thus modifies the behavior of the process.

Let us consider three simple types of effects of the feedback :          

Positive :

 

The feedback acts on the control in the same direction as the evolution of the received result, and so tends to strengthen this one.

Negative :

 

The feedback acts on the control in the direction opposite to the evolution of the received result, and so tends to reduce this one.

Corrective :

 

The result received by feedback is compared with a desired result, and the difference acts on the control in sort that the received result evolves towards the desired result.

 

The positive feedback makes the process unstable because the result increases more and more until  its possible maximum is reached. For example, during an amateur rock concert, the bad acoustic quality of loudspeakers makes that it is often difficult for the various musicians to distinguish well their own instruments, what leads them to increase the volume to better hear themselves. This increases more and more the distortions, and finally the concert is performed with all the amplis with maximal power. This type of process is also qualified of divergent or inflationary, or even explosive.

The negative feedback stabilizes the process towards a zero result. For example, a teacher can obtain gradually the silence in his class by speaking at a level slightly lower than the ambient hubbub. This type of process is also qualified of convergent or deflationary.

The corrective feedback also stabilizes the process, but towards an intended result. It is in fact a negative feedback, that tends to minimize the distance between the actual result and the desired result. For example, to tune a string instrument on the diapason, the instrumentalist stretches out the string if the note is too low pitched, and releases it if it is too high pitched, and repeats until satisfaction. This type of process, convergent too, is considered as optimal if the stabilization on the objective is obtained in a shortest possible way. In our example, a novice tuner will turn numerous times the key in both ways, while an expert will make practically a single gesture.

To illustrate, the following table shows some examples of feedback at the different levels of space :


 

Space level

Considered items

Examples of positive feed-back 

Examples of negative or corrective feed-back 

Physical

Vibration waves of molecules of air.

Larsen effect, due to the reception by the membrane of the microphone of a pressure of air in sync with the vibration of the membrane of the loudspeaker.

Systems of active noise reducing used in the aviation (by superimposing of an identical noise in opposition of phase).

Acoustic

Signals of vibration waves.

Example (quoted above) of the rock concert with maximum power .

Dynamic compression (for example: automatic correction of volume on amateur's camcorders and  sound recorders).

Sound

Sound objects.

Group self-excitation (applauses chanted for example).

Self-listening, indispensable to sing or play right, and even speak (without shouting as a deaf person!).

Musical

Sound beings.

Burst advertising of a "hit",  fashion due to the collective autosuggestion.

To listen again to self-criticism.

Figure 2 : examples of feedback at different levels of space

 

Dynamics ot the feedback

In the reality, the feedback loops are more complex than the above diagram would let it suppose:

The effectively perceived result does not represent reliably the really produced result, because the perception results itself from processes which are not neutral for the author of this producing; for the music, we saw that the chain of processes contains the following levels, each containing limits and transformations :

vibration of the eardrum and excitement of the hearing nerve ;

frequencial analysis and transmission to the brain ;

hearing and immediate memorization of the sound objects ;

listening, producing the aesthetic interest.

There are delays and latencies in the loop, mainly for two reasons :

as well as the spread of the sound in the air is not intantaneous, the human reaction to stimuli is not immediate ;

the music can be deliberately stored in a temporary way through an audio recording or on paper, to be listened again or read again later.

feedback2

Figure 3 : feedback with latencies

 

Effects of perception processes 

Our previous analysis made us to notice the limits and the constraints of the listening chain, for example for the perception of durations, presences and colors, or for the understanding of forms. The feedback allows the musician to verify that his production can be listened. However his own conditions of listening are not identical to those of his listeners.

By comparing the topologies related to the positions of the listener and the composer, we however noticed that the perception of the characters of the music is not the same. For a listener, every new perception is relative to the previous ones, while the musician get the general overview, excepting if he improvises. It can then be interesting for the composer to forget a while the music which was in his mind to listen to in a naive attitude.

Effects of delays

The analysis of the effects of temporal gaps is essential in the understanding of the dynamic behavior of the systems with feedback. Without developing the whole theory, let us keep the most interesting phenomenon: it is about the resonance, which is a spontaneous vibration caused by a feedback system with delays.

The phenomenon of resonance is the one which is at the origin of almost all the musical instruments. Besides, it is a similar phenomenon  that makes the imagination to put himself in favorable capacities to create the music... !

At first let us explain briefly by examples of the common life how the delays can cause very strong oscillations on a system that should normally converge to a stable behavior thanks to the corrective feedback.

In an intense stream of the road traffic, every driver accelerates or slows down to keep a correct distance with the previous vehicle. He relies on the estimation of the accelerations and the slowings down of his predecessor, but, his reaction being not immediate, he is leaded to accelerate or to brake more energetically than his predecessor. The action is more and more stressed for the drivers at the back of the line, provoking finally the well known, absolutely inevitable phenomenon of accordion, even when everybody is attentive, until to degenerate into a suite of chokepoints spaced out by empty sections.

The alcohol slowing down the reflexes of balance, the trajectory from a point to another for the common drunk man famously oscillates around the theoretical straight line...

When a significant time is necessary to transmit or understand  the information, any adjustment process often tends to a oscillatory phenomenon, because the answers to out-of-date stimuli are unsuitable, even in contradiction with the reality which it is necessary to master (did you already climb on your roof to direct the television mast thanks to the indications roared by the person situated in the living room?).

The purpose of these examples is not to bitterly notice that it is very difficult to do what we would like, but rather to bring to light that any system including a feedback or a loop naturally tends to oscillate, with a specific period which depends directly on delays in the loop. It is the period of resonance of the system.

Effects of feedback on musical creation

In the field of the artistic creation, when the thought drives the action and the action drives the thought, this swing can generate as well unwanted effects of offbeat as positive effects of emphasizement or surprise. Particularly, at the stage of the musical creation, a resonant feedback system is instinctively initated by the musicians, to begin and enrich a creative process which develops spontaneously its own rhythms. And so the idea takes shape.

The system of feedback is itself complex: it includes at the same moment direct returns while the musician plays, and delayed returns consisting in replaying the music from a version stored in a written or recorded artefact.

Direct feed-back

The direct feedback loops send back stimuli resulting from the action of playing the music. The latent periods do not exceed the few seconds of the perception span. These stimuli can include:

the effects of the music on the musician, in the same way as on the listener ;

the stimuli of the other senses, inferred by the response of the instrument to the gestures of the musician: touch, elasticity, inertness, vibrations, ...

the physical sensations when doing the gestures: balance, swing, fluidity, speed, heat, perspiration, pain. This is also worth for a conductor !

Delayed feed-back

Almost always the music creators will find convenient to establish latent periods by the following processes:

reading again of the score,

rehearsal (according to the score, the  improvisation grid or any written representation),

to listen again to the recorded music.

So the multiple feedback loops overlap within the system of musical creation, opening occasions of multiple resonances which the musician will exploit to give rhythm to the achievement of his intentions.

 

 


 

 

 

Imaginary music ISBN 978-2-9530118-0-7 copyright Charles-Edouard Platel

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