Method and device for narrow-band noise suppression in a vehicle passenger compartment

A real-time active method for attenuating, through feedback, a narrow-band noise, essentially mono-frequency at least one determined frequency, in a vehicle passenger compartment, by emitting a sound through at least one transducer, typically a loud-speaker, controlled by a signal u(t) or U(t) according to a SISO or MIMO case respectively, generated by a programmable calculator, as a function of a signal of acoustic measurements y(t) or Y(t) according to the case, performed by at least one acoustic sensor, typically a microphone, wherein the use of a sensor corresponds to a SISO, single input single output, mono-variable, case, and the use of several sensors corresponds to a MIMO, multi-inputs-multi-outputs-variables case, and,

• in a first phase of design, the electroacoustic response of the unit formed by the passenger compartment, the transducer and the sensor, is modeled by an electroacoustic model as an electroacoustic transfer function that is determined and calculated, a control law being then determined and calculated from a global model of the system in which the control law is applied to the electroacoustic transfer function whose output additionally receives a noise signal to be attenuated p(t) to give the signal y(t) or Y(t) in said design phase, said control law making it possible to produce the signal u(t) or U(t) as a function of the acoustic measurements y(t) or Y(t), and
• in a second phase of use, said calculated control law is used in the calculator to produce the signal u(t) or U(t) then sent to the transducer as a function of the signal y(t) or Y(t) received from the sensor for attenuating said noise,
• characterized in that a control law is implemented, which comprises the application of a Youla parameter to a central controller and which is such that only the Youla parameter has coefficients that depend on the frequency of the noise to be attenuated in said control law, the central controller having fixed coefficients, the Youla parameter being in the form of an infinite impulse response filter, and in that, after determination and calculation of the control law, at least said variable coefficients are stored into a memory of the calculator, preferably in a table as a function the determined noise frequency(ies) p(t) used in the design phase, and in that, in the use phase, in real time:
• the current frequency of the noise to be attenuated is collected,
• the calculator is caused to calculate the control law, comprising the central controller with the Youla parameter, using as the Youla parameter the memorized coefficients of a determined frequency corresponding to the current frequency of the noise to be attenuated.