An electronic system includes a fan module, an embedded controller, an error microphone, an active noise cancellation controller, and a micro speaker module. The error microphone is configured to output an error signal by detecting the noise level during the operation of the electronic system. According to the error signal and the fan information provided by the embedded controller, the active noise cancellation controller calculates the narrow-band noises associated with the actual single-blade fundamental frequency noise and the actual BPF fundamental frequency noise generated by the fan module, and drives the micro speaker module accordingly for providing a noise cancellation signal. The error signal may be reduced to zero by adaptively adjusting the noise cancellation signal for canceling the noises generated during the operation of the electronic system.

The present disclosure provides a method for determining an arrangement of reference sensors for active road noise control (ARNC) in a vehicle with an automatic calibration system. The method includes mounting a plurality of vibrational sensors on a plurality of structure elements of the vehicle to generate a plurality of vibrational input signals and mounting at least one microphone inside a cabin of the vehicle to capture at least one acoustic input signal. The method further includes determining an arrangement of reference sensors from the plurality of vibrational sensors by determining a subset of vibrational sensors which sense the main mechanical inputs of road noise contributing to the at least one acoustic input signal.

A headphone having a speaker, a feedforward microphone, a feedback microphone, and an OED processor. The speaker is configured to transmit an audio playback signal based on a headphone audio signal. The feedforward microphone is configured to sense an ambient noise signal and transmit a feedforward microphone signal based at least in part on the ambient noise signal. The feedback microphone is configured to sense a total audio signal and transmit a feedback microphone signal based at least in part on the total audio signal, in which the total audio signal is the sum of the audio playback signal and at least a portion of the ambient noise level. The OED processor is configured to determine whether the headphone is off ear or on ear, based at least in part on the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal.

A headphone having a speaker, a feedforward microphone, a feedback microphone, and an OED processor. The speaker is configured to transmit an audio playback signal based on a headphone audio signal. The feedforward microphone is configured to sense an ambient noise signal and transmit a feedforward microphone signal based at least in part on the ambient noise signal. The feedback microphone is configured to sense a total audio signal and transmit a feedback microphone signal based at least in part on the total audio signal, in which the total audio signal is the sum of the audio playback signal and at least a portion of the ambient noise level. The OED processor is configured to determine whether the headphone is off ear or on ear, based at least in part on the headphone audio signal, the feedforward microphone signal, and the feedback microphone signal.

A headphone detector including a headphone and a processor. The headphone has a microphone and a speaker, and the microphone is configured to generate an audio signal based on an output of the speaker. The processor is configured to receive the audio signal, determine a characteristic of the audio signal, and assess whether the headphone is on ear or off ear based on a comparison of the characteristic to a threshold. The threshold corresponds to one or more of an audio response of the audio signal at a corresponding frequency and an audio response of a feedback microphone signal at a corresponding frequency, under one or more known conditions.

A headphone detector including a headphone and a processor. The headphone has a microphone and a speaker, and the microphone is configured to generate an audio signal based on an output of the speaker. The processor is configured to receive the audio signal, determine a characteristic of the audio signal, and assess whether the headphone is on ear or off ear based on a comparison of the characteristic to a threshold. The threshold corresponds to one or more of an audio response of the audio signal at a corresponding frequency and an audio response of a feedback microphone signal at a corresponding frequency, under one or more known conditions.

The present disclosure provides a method for determining an arrangement of reference sensors for active road noise control (ARNC) in a vehicle with an automatic calibration system. The method includes mounting a plurality of vibrational sensors on a plurality of structure elements of the vehicle to generate a plurality of vibrational input signals and mounting at least one microphone inside a cabin of the vehicle to capture at least one acoustic input signal. The method further includes determining an arrangement of reference sensors from the plurality of vibrational sensors by determining a subset of vibrational sensors which sense the main mechanical inputs of road noise contributing to the at least one acoustic input signal.

A headphone detector including a headphone and a processor. The headphone has a microphone and a speaker, and the microphone is configured to generate an audio signal based on an output of the speaker. The processor is configured to receive the audio signal, determine a characteristic of the audio signal, and assess whether the headphone is on ear or off ear based on a comparison of the characteristic to a threshold. In another aspect, an off-ear detection (OED) system includes a headphone and an OED processor. The headphone has a speaker, a feedforward microphone, and a feedback microphone. The OED processor is configured to determine whether the headphone is off ear or on ear, based at least in part on a headphone audio signal, a feedforward microphone signal, and a feedback microphone signal.

A method of operating an audio system in a vehicle includes providing m number of microphones disposed within a passenger compartment of the vehicle. The microphones produce a plurality of microphone signals. Within the passenger compartment of the vehicle, k number of loudspeakers are provided. A plurality of convergence factors for use in performing active noise control are estimated. The estimating includes calculating an Eigen value () of an autocorrelation matrix of a passenger compartment transfer function as ${}_k\left(\right)=\frac{{A_k\left(\right)}^2}{2},$
wherein A.sub.k() is the frequency response of the passenger compartment transfer function. A frequency .sub.min of a local minimum of () is determined. A largest stable value for Max(.sub.min) is found by experimentation, wherein a rotational speed of an engine of the vehicle, expressed in revolutions per minute, f.sub.rpm=2.sub.min. A calibration factor is calculated as L=(.sub.min)Max(.sub.min). All values of Max() are estimated as $\mathrm{Max}\left(\right)=\frac{L}{\left(\right)}.$
A plurality of active noise controlled audio signals are transmitted to the loudspeaker. The active noise controlled audio signals are dependent upon the microphone signals and the estimated convergence factors.

A method of operating an audio system in a vehicle includes providing m number of microphones disposed within a passenger compartment of the vehicle. The microphones produce a plurality of microphone signals. Within the passenger compartment of the vehicle, k number of loudspeakers are provided. A plurality of convergence factors for use in performing active noise control are estimated. The estimating includes calculating an Eigen value () of an autocorrelation matrix of a passenger compartment transfer function as

[00001]${}_k\left(\right)=\frac{{A_k\left(\right)}^2}{2},$

wherein A.sub.k() is the frequency response of the passenger compartment transfer function. A frequency .sub.min of a local minimum of () is determined. A largest stable value for Max(.sub.min) is found by experimentation, wherein a rotational speed of an engine of the vehicle, expressed in revolutions per minute, f.sub.rpm=2.sub.min. A calibration factor is calculated as L=(.sub.min)Max(.sub.min). All values of Max() are estimated as

[00002]$\mathrm{Max}\left(\right)=\frac{L}{\left(\right)}.$

A plurality of active noise controlled audio signals are transmitted to the loudspeaker. The active noise controlled audio signals are dependent upon the microphone signals and the estimated convergence factors.