An acoustic sensor (e.g., for use in a piezoelectric MEMS microphone) includes a substrate and a cantilever beam attached to the substrate. The cantilever beam has a proximal portion attached to the substrate and extends to a distal tip at a free end thereof. The cantilevered beam has a multilayer structure with a plurality of piezoelectric layers and a plurality of metal electrode layers, at least a portion of one of the piezoelectric layers interposed between two metal electrode layers. One or more direct current voltage sources are electrically connected to one or more of the plurality of metal electrode layers and configured to apply a direct current bias voltage between at least two of the plurality of metal electrode layers to deflect the cantilever beam to at least partially counteract a deflection of the cantilever beam due to a residual stress in the cantilever beam.

The present disclosure relates to an acoustic output apparatus. The acoustic output apparatus comprising: at least one low-frequency acoustic driver that outputs sound from at least two first sound guiding holes; at least one high-frequency acoustic driver that outputs sound from at least two second sound guiding holes; and a controller configured to cause the low-frequency acoustic driver to output sound in a first frequency range, and cause the high-frequency acoustic driver to output sound in a second frequency range, wherein the second frequency range includes frequencies higher than the first frequency range.

The present disclosure relates to an acoustic output apparatus. The acoustic output apparatus comprising: at least one low-frequency acoustic driver that outputs sound from at least two first sound guiding holes; at least one high-frequency acoustic driver that outputs sound from at least two second sound guiding holes; and a controller configured to cause the low-frequency acoustic driver to output sound in a first frequency range, and cause the high-frequency acoustic driver to output sound in a second frequency range, wherein the second frequency range includes frequencies higher than the first frequency range.

A signal processer is configured to decrease total harmonic distortion plus noise of an output signal generated from an input signal. The signal processer includes a mixer, a pulse-width modulator, a power stage circuit, and a feedback circuit. The mixer is configured to mix the input signal and a feedback signal to generate a mixed signal. The pulse-width modulator is configured to module the mixed signal to generate a modulated signal and output the modulated signal from an output terminal of the pulse-width modulator. The power stage circuit is configured to amplify the modulated signal to generate the output signal and output the output signal from an output terminal of the power stage circuit. The feedback circuit is configured to generate a feedback signal selectively according to the modulated signal or the output signal.

A signal processer is configured to decrease total harmonic distortion plus noise of an output signal generated from an input signal. The signal processer includes a mixer, a pulse-width modulator, a power stage circuit, and a feedback circuit. The mixer is configured to mix the input signal and a feedback signal to generate a mixed signal. The pulse-width modulator is configured to module the mixed signal to generate a modulated signal and output the modulated signal from an output terminal of the pulse-width modulator. The power stage circuit is configured to amplify the modulated signal to generate the output signal and output the output signal from an output terminal of the power stage circuit. The feedback circuit is configured to generate a feedback signal selectively according to the modulated signal or the output signal.

A method for detecting a prominent tone of an input audio includes establishing a first analysis audio signal based on the input audio signal, establishing a second analysis audio signal based on the input audio signal, wherein an analysis audio signal of the first analysis audio signal and the second analysis audio signal is established by applying an analysis audio filter to the input audio signal, comparing the first analysis audio signal and the second analysis audio signal to obtain an energy level contrast, and determining a representation of the prominent tone by converting the energy level contrast by a contrast-to-frequency mapping function.

A system configured to perform microphone occlusion event detection. When a device detects a microphone occlusion event, the device will modify audio processing performed prior to speech processing, such as by disabling spatial processing and only processing audio data from a single microphone. The device detects the microphone occlusion event by determining inter-level difference (ILD) values between two microphone signals and using the ILD values as input features to a classifier. For example, when a far-end reference signal is inactive, the classifier may process a first ILD value within a high frequency band. However, when the far-end reference signal is active, the classifier may process the first ILD value and a second ILD value within a low frequency band.

A vehicular apparatus having at least one of a voice calling function and a voice recognition function, the apparatus comprising a voice input unit including a plurality of microphones, the voice input unit being disposed between a driver's seat and a passenger seat with respect to a vehicle width direction; and a control unit configured to control a directionality direction and a gain level of each of the plurality of microphones, wherein the control unit controls the directionality directions of the plurality of microphones in two directions, the two directions being a driver's seat side and a passenger seat side, and controls a gain level on the passenger seat side to be lower than a gain level on the driver's seat side.

A transducer system has a transducer configured to receive an incident signal and produce an output signal as a function of the incident signal. As known in the art, the output signal has a −3 dB point. The transducer system also has circuitry operatively coupled with the transducer. The circuitry includes an amplifier with an output configured to produce an amplified signal as a function of the output signal. In addition, the circuitry further has a positive feedback loop and a negative feedback loop that both are electrically coupled between the transducer and the amplifier. The positive feedback loop is configured to move the −3 dB point in a first frequency direction. Conversely, the negative feedback loop is configured to move the −3 dB point in a second frequency direction. Preferably, the first and second frequency directions are different.

A transducer system has a transducer configured to receive an incident signal and produce an output signal as a function of the incident signal. As known in the art, the output signal has a −3 dB point. The transducer system also has circuitry operatively coupled with the transducer. The circuitry includes an amplifier with an output configured to produce an amplified signal as a function of the output signal. In addition, the circuitry further has a positive feedback loop and a negative feedback loop that both are electrically coupled between the transducer and the amplifier. The positive feedback loop is configured to move the −3 dB point in a first frequency direction. Conversely, the negative feedback loop is configured to move the −3 dB point in a second frequency direction. Preferably, the first and second frequency directions are different.