A drive system includes an actuator including an electric motor, a microphone, and a sound generator emitting a sound in response to a signal derived from sound caught by the microphone. The microphone is attached to the actuator. This drive system makes it easy to establish an optimal positional relationship between the microphone and the noise source in the actuator, thereby properly reducing noise arising from the actuator.

A microphone system may include a measuring device that includes a plurality of sound elements and a semiconductor chip connected to the sound elements and receives a vibration signal and a noise signal from the outside to cancel the vibration signal and changes a phase of the noise signal to output a reverse phase noise signal; and a driver that is connected to the semiconductor chip and is included in a front glass of a vehicle and vibrates in response to the reverse phase noise signal to cancel a noise signal inputted from the outside.

An acoustic conversion device for an active noise control is provided. The acoustic conversion device can effectively suppress or remove noise by controlling variation in a lowest resonance frequency. A volume of a closed space is smaller than an equivalent compliance air volume of a speaker unit. Therefore, motion of a vibration plate, an edge and a damper is suppressed, it is possible to restrain the edge and the damper from being deteriorated with time, variation in lowest resonance frequency can be suppressed, phase of emitted sound can be less prone to be deviated from opposite phase of noise, and it is possible to effectively suppress or remove noise.

Rotor noise cancellation through the use of mechanical means for a personal aerial drone vehicle. Active noise cancellation is achieved by creating an antiphase amplitude wave by modulation of the propeller blades, by utilizing embedded magnets through an electromagnetic coil encircling the propeller blades. A noise level sensor signals the rotor control system to adjust the frequency of the electromagnetic field surrounding the rotor and control the speed of the rotor. An additional method comprises of incorporating a phase lock loop within the control system configured to determine the frequencies corresponding to the rotors and generate corrective audio signals to achieve active noise cancellation.

Systems and methods for reducing noise or vibration generated by an internal combustion engine are described. An engine controller is arranged to operate the working chambers of the engine in a cylinder output level modulation manner A noise/vibration reduction unit actively control of a device that is not a part of the powertrain. The device is controlled in a feed forward manner to alter an NVH characteristic of the vehicle in a desired manner based at least in part on a characteristic of the cylinder output level modulation operation of the engine.

A synthetic jet assembly includes a synthetic jet having a cavity and an opening formed therein. The synthetic jet assembly also includes an actuator element coupled to a second surface of the body to selectively cause displacement of the second surface, and a control unit electrically coupled to the actuator element. The control unit is configured to transmit a multi-frequency drive signal to the actuator element, the multi-frequency drive signal comprising a cooling frequency component and an acoustic frequency component superimposed on the cooling frequency component. The cooling frequency component causes a cooling jet to eject from the opening of the body. The acoustic frequency component produces a desired audible output.

A sound control device mounted in a vehicle and control method include measuring a drive signal input to a speaker, wherein the drive signal is generated in response to an input signal including at least one of a noise control signal and an audio signal, estimating a state of a voice coil of the speaker including at least one of displacement and temperature of the voice coil, based on the drive signal and a model of the speaker, and adjusting the input signal based on the state of the voice coil.

Provided is an electroacoustic transducer capable of reducing the thickness and weight of the entire pillow when a speaker is embedded in the pillow or a headrest, enabling miniaturization of a device by causing the position of the speaker to be close to a position at which the head is placed, and improving the accuracy of signal processing by reducing a load of the signal processing in a case where active noise control is performed, thereby improving a noise reduction effect. The electroacoustic transducer includes: an electroacoustic transduction unit having an electroacoustic transduction film including a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature and thin film electrodes respectively laminated on both surfaces of the polymer composite piezoelectric body, and an elastic support disposed in close contact with one principal surface to bend the shape of the electroacoustic transduction film; and a first cushion layer that is in contact with the electroacoustic transduction film on an electroacoustic transduction film side of the electroacoustic transduction unit to cover the electroacoustic transduction unit and is formed of a three-dimensional solid knitted fabric.

An electroacoustic transduction film including a polymer composite piezoelectric body in which piezoelectric body particles are dispersed in a viscoelastic matrix formed of a polymer material having viscoelasticity at a normal temperature, and thin film electrodes respectively laminated on both surfaces of the polymer composite piezoelectric body is included, and two or more of the electroacoustic transduction films are laminated, and a gap between the adjacent electroacoustic transduction films is less than or equal to 3 cm.

An acoustic conversion device for an active noise control is provided. The acoustic conversion device can effectively suppress or remove noise by controlling variation in a lowest resonance frequency. A volume of a closed space is smaller than an equivalent compliance air volume of a speaker unit. Therefore, motion of a vibration plate, an edge and a damper is suppressed, it is possible to restrain the edge and the damper from being deteriorated with time, variation in lowest resonance frequency can be suppressed, phase of emitted sound can be less prone to be deviated from opposite phase of noise, and it is possible to effectively suppress or remove noise.