Tutorials

Alberto Bernardini – Dipartimento di Elettronica Informazione e Bioingegneria (DEIB), Politecnico di Milano

Audio systems can be often accurately described using equivalent circuit models that are capable to represent their behavior in multiple physical domains (e.g., electrical, magnetic, mechanical, acoustic) in a unified fashion. Moreover, such models allow us to efficiently emulate audio systems in the digital domain by employing circuit simulation methods. In this tutorial, we will highlight a further advantage of representing audio systems using circuits. In fact, we will show how, given an audio system represented as a circuit with input and output signals, it is possible to design the corresponding inverse circuital system. As a first example of application of this inverse system design approach, we will describe a method for loudspeaker virtualization through digital audio signal preprocessing. This method can be used to alter the behavior of a physical loudspeaker in such a way to match that of a target loudspeaker. Special cases of this approach are loudspeaker linearization and equalization. The proposed virtualization algorithm is extensively tested both through simulations and applications to real loudspeakers. Moreover, we will show how a similar reciprocal approach can be used for the virtualization of acoustic sensors, like microphones or guitar pickups. Finally, further possible examples of application and related future research works are discussed.