Active noise control in light aircraft cabin using multichannel coherent method

Abstract

The paper deals with active noise control system for the cabin of a light aircraft. Basic system uses coherent averaging method of the residual error signal to produce signal that drives secondary source. Advanced versions of this system use a-priori information about noise waveform and adaptation process begins with the assumed waveform (sinus signal of adequate amplitude, phase and frequency or even low pass ltered referent noise signal). After testing single-channel system, achieved noise suppression is verified with additional simulation considering measured acoustic characteristics of real aircraft cabin (characterized by impulse responses). System could be extended to multichannel version of type SIMO (Single Input Multiple Output) where the same tacho/referent signal after adequate delay (acoustic propagation of the noise signal through the cabin) drives eight single-channel systems connected with multiple gain-delay combinations to reduce crosstalk between individual channels.