Simulations and experiments for hybrid noise control systems

A Muffler with Adaptive Acoustic Properties

“…In recent years, a great deal of effort has been put into the research of adaptive reactive mufflers [6], [11], [15] and [16]. Instead of loudspeakers, adaptive mufflers use non-acoustic actuators to eliminate the problems of acoustic feedback, which is one of the prevailing problems in the practical usage of ANC.…”

“…Cherrier et al [18] created perforated panel resonators with an active control of their openings (so-called necks). Chen and Too [11] combined the principle of the reactive muffler with an actively controlled loudspeaker. Kostek and Franchek [19] proposed a hybrid resonator with an actively controlled cavity of the Helmholtz resonator.…”

“…ANC is a method for reducing unwanted noise with its "antinoise", which is specifically calculated and generated to be a copy of unwanted noise with a reversed phase. ANC can be applied in various situations for suppressing unwanted noise [8], and is widely used in cabins [9] and [10], in ducts [11] and [12] and also in engine exhaust systems [13] and [14]. The ANC method applied to vehicle exhaust noise reduction has some advantages, such as no increase in the exhaust backpressure, improving the performance of the engine, and reducing fuel consumption.…”

Adaptive muffler based on controlled flow valves

“…2,6,[10][11][12] The main advantage of this muffler is its ability to control its effects in real time and consequently achieve higher noise reduction under various levels of input noise. Their efficiency in noise reduction can be tuned to desired levels and/or to the welfare of the users' subjective perspective.…”

“…ANC is often applied in various situations for suppressing unwanted noise. 4 It is widely used in ducts, 5,6 in cabins, 7,8 and also in engine exhaust systems. 9 Mufflers with ANC usually use a loudspeaker to cancel the exhaust noise.…”