Method for artificially reproducing an output signal of a nonlinear time-invariant system

The invention relates to a method for reproducing an output signal of a non-linear time invariant system, in particular a method used for example for artificially reproducing a particular acoustic effect going close to the real one. Such acoustic effect can be, for example, the sound that can produce a sound chest of a particular musical instrument when it is played or a sound amplified by a non-linear amplifier such as a tube amplifier. Each of the aforesaid systems, namely a sound chest of a musical instrument or a tube amplifier, or the sound produced by combinations of the aforesaid systems, is a nonlinear system. As a result, each of the aforesaid systems modifies the input signals sent, so the corresponding output signals are distorted with respect the respective input signals. This means that the output signal has different frequency components compared to the input signal. In particular, the output signal may have a plurality of harmonics at frequencies that are different the one from each other and different from the frequency/frequencies of the input signal, even if the input signal has only one component at fundamental frequency. The harmonic distortions introduced by each system characterize the sound generated by each system, making the sound unique and recognizable among others. This means that each sound generated by a system differs from the sound generated by another system because of its harmonic content. It follows that a system is distinguished from another one because of the harmonic distortions it introduces in the sound produced by the system.