A system for modifying an audio signal comprises a computer including a first digital signal processor (DSP). The first DSP includes a first module and a second module. The first module is coupled to the interface to provide a musical instrument with a set of testing input signals and obtain a set of testing output signals from the musical instrument via the interface. The second module is configured to perform functions including: analyzing the set of testing output signals to obtain a set of parameters, constructing an acoustic transducer to model characteristics of the musical instrument based on the set of parameters, and receiving the audio signal to modify the audio signal using the acoustic transducer, wherein the first DSP module obtains the set of parameters at least by identifying occurrences when an output level state determined at least based on the set of testing output signals significantly changes.

A method of modeling a characteristic of a non-linear system, comprises feeding testing input signals into the non-linear system to obtain testing output signals corresponding to the testing input signals, wherein the testing input signals include a first testing input signal and the testing output signals include a first testing output signal, identifying occurrences when an output level state in at least one specific frequency band of the first testing output signal significantly changes under the first testing input signal so as to obtain a first profile, and modeling the characteristic based on the first profile.

The present invention relates to a face alignment virtual piano system using computer vision technology. Traditionally, projector-based virtual pianos are centered on the projection, this limits the size of virtual pianos. The system circumvents this issue by utilizing facial landmark tracking to accurately and dynamically adjust the virtual keyboard's alignment based on the user's face position. In doing so the position of the keyboard is no longer fixed to the position of the projection, but rather it is determined by the user's position. This not only significantly enhances the freedom of movement of the user, but also allows for the possibility of full 88-key pianos.