Analysis of Possible Algorithms for Active Noise Control of Siren Noise into an Ambulance

This paper discusses a potential application of Active Noise Control (ANC) algorithms for the reduction of ambulance siren noise inside the vehicle. The study starts from the analysis of ANC techniques available in literature and currently used in industrial and consumer applications. The concept of ANC is based on the introduction of a canceling “antinoise” wave through a suitable speaker array known as secondary sources. These generators are managed through a specific signal-processing algorithm tailored according to the characteristics of the noise generated by the primary source that has to be cancelled. The primary signal is recorded by the control microphones and then processed by the ANC algorithm. An “antinoise” is then generated to reduce the primary source noise in a specific target zone. Based on the fundamental principles of wave superposition and wave cancellation, ANC technique is a very effective solution from a theoretical point of view; nevertheless, this technique faces numerous practical implementation problems and despite the wide number of available industrial and domestic applications, it is still poorly exploited. In this paper, the state of the art about most advanced ANC techniques and applications is analyzed. In particular, the implementation of adaptive signal processing algorithms and digital signal processing (DSP) in ANC systems is analyzed.