See also: Stamp

In Music, the stamp is one of the characteristic of the sound. This essential component, though lengthily studied, was only tardily included/understood.

The Organology, under the impulse of the factors of instruments, developed its study on purely intuitive bases, the smoothness of our direction enabling us to distinguish from the even tiny differences between various categories of sonorities. The Compositeur S also strongly contributed to this study, the orchestration having developed a theoretical base with the polyphonies of stamps. On the plan Psychoacoustics, the conditions of listening can also vary the appreciation of the color of an instrument, and thus of its stamp.

Harmonic decomposition

The first work of Joseph Fourier on the decomposition of a periodic function in a sum of sinusoidal functions simple had let think that the solution of the problem was to be in the harmonic analysis of the its.

The increasingly sophisticated apparatuses of analysis of sound came to cancel these assumptions. The Sonagraphe, whose discovery goes back to the years 1940 in Beautiful Laboratories, made it possible to explore more before the decomposition of the partial sound in S and harmonic. The only curve of envelope, which expresses the amplitude according to time, appeared inadequate with the description of the characteristics of the stamp.

Only the sonagraphe, apparatus of chart of the totality of dimensions of the phenomenon (Time - Frequency - Amplitude) made it possible to follow an evolutionary spectrum, whose each component has a relative intensity which evolves/moves with time.

Other parameters of the stamp

Other elements, physically simple to describe, are only intuitively perceived like influencing our Perception stamp, and the importance of their role within the field of this recognition is difficult to apprehend. Brightness, the formants, for example, but also the Vibrato, sound texture. Helmholtz in its physiological theory of the music, presented a theory being based on the description of the harmonics of a its periodical and the calculation of their intensity by means of resonators.

He in parallel discovered the frequencies of partial inharmonic and observed their importance in the nature of the sound. With its continuation, Carl Stumpf, philosopher and German psychophysiologist, noted in the years 1930, the importance of the transients (negligible portion of the attack of the sound), of the vibrato, the spectral components (formantic areas ), of the fall in the dimension of the stamp. The portion of attacks is essential with the identification of the instrument. These transients of attack are phenomena which can last 20 ms up to 200, even 300 ms, according to the instruments, and which affects any modification of the perception of the stamp. This work revealed that the properly musical characters of the sounds are registered in the stationary part

But one especially must with work of the LAM (Laboratory of Musical Acoustics of the university Paris VI), directed by Emile Leipp in the Seventies, to have shown that many components of the sound (discrete and continuous) are only psychological components, psychoacoustics, which take seat only at the cerebral level , neuronal of the recognition of the stamp. The study of the modes of set of certain interpreters reveals for example that the stationary phase is continuously differentiated and perpetually varies during the execution of a work. Many components timbrales are thus alive, dynamic elements: even if our ear cannot recognize them intuitively, it can do it unconsciously.

Analyze-synthesis

Starting from these analyzes, the sound Synthèse proceeded by decomposition-recombining to work out its models, and thus made it possible to cross an additional step in the comprehension of the mechanisms of the recognition of the stamp.

Initiated for the analyze-synthesis of the sounds coppered by Jean-Claude Risset (between 1964 and 1969), the study of the spectral components of the stamp of the instruments was taken again by James Andrew Moorer and John Michael Grey which reflects forward a spectrum with three dimensions (frequency, intensity, time), like by Dexter Morrill in a remarkable study of the trumpet: these analyzes made it possible to emphasize the temporal evolution of the spectrum, and revealed the importance of the attack and the dynamic envelope.

They show the progressive emergence of certain harmonics (of high row) stronger in the stationary part than in the attack and the decrease. The concept of space of stamps introduced (in 1975) per J. Mr. Grey opened the way with the discussed concept of musical material, by locating it in a multidimensional representation. Thus, the passage to representations with N (>2) dimensions is particularly significant taking possession of the mathematical paradigms for the representation of the stamp.

We thus need completely a new vision to evaluate this conceptual field of stamp. To judge a stamp amounts comparing two matrices of information. Blow, research which aims at making stamp a structural component reveals an essential difficulty and causes a reflection on the formal function of a badly known parameter.

Gradually the integration of certain scientific data makes it possible new parameters of the sound vibration to take seat in our knowledge of the formation of the stamp and in that more creative of the field of influence of the function timbrale. It is thus, as we said, of the transients, the attack, the vibrato, the spectral components (formantic areas), of the fall… But if a classification by forms (the shapes of waves, attacks, envelope, spectrum) would be enough with the establishment to a typology to the sound one, it is not sure so much that such a classification can be carried out at the musical level, this level is located in another hierarchy. In fact, many components of the sound (discrete and continuous) are only components Psychologiques, which take seat only at the level cerebral, neuronal, and the data to which they are attached in the music are founded on a basis more Esthétique that rational.