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.

An active noise cancellation (ANC) system is provided with at least one loudspeaker to project an anti-noise sound within a room in response to receiving an anti-noise signal. A first controller is programmed to adjust a transfer function indicative of a secondary path between the at least one loudspeaker and at least one microphone within the room based on a resonance frequency of the at least one loudspeaker, and to generate the anti-noise signal based on the adjusted transfer function.

Disclosed herein are a speaker device having a built-in microphone and a noise cancellation method using the same. The speaker device having the built-in microphone includes a microphone module picking up sound from a medium to generate a sound pickup signal, a speaker driver transmitting vibration corresponding to a reverse-phase signal of the sound pickup signal to tire medium, and a controller receiving the sound pickup signal from the microphone module, generating the reverse-phase signal of the sound pickup signal, and transmitting the reverse-phase signal to the speaker driver.

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.

According to one embodiment, a sound emitting apparatus includes an elastic member, three or more excitation actuators, and a control circuit. The elastic member has an annular shape. The excitation actuators are arranged at a predetermined angular interval on the elastic member and are configured to apply vibration to the elastic member. The control circuit is configured to generate drive signals for driving the three or more excitation actuators. There is a phase difference between drive signals for two excitation actuators separated by the predetermined angular interval, the phase difference depending on an order of a Lobe mode being a vibration mode excited on the elastic member and the predetermined angular interval.

A speaker (10) includes a radiation surface (15). The radiation surface (15) has a first region (15a), a second region (15b), and a third region (15c) between the first region (15a) and the second region (15b). When an axis passing through the third region (15c) and extending away from the radiation surface (15) is defined as a reference axis (10X), the speaker (10) forms a first wavefront (16a) propagating from the first region so as to approach the reference axis (10X) and a second wavefront (16b) propagating from the second region (15b) so as to approach the reference axis (10X).

According to one embodiment, a sound emitting apparatus includes an elastic member, three or more excitation actuators, and a control circuit. The elastic member has an annular shape. The excitation actuators are arranged at a predetermined angular interval on the elastic member and are configured to apply vibration to the elastic member. The control circuit is configured to generate drive signals for driving the three or more excitation actuators. There is a phase difference between drive signals for two excitation actuators separated by the predetermined angular interval, the phase difference depending on an order of a Lobe mode being a vibration mode excited on the elastic member and the predetermined angular interval.

A noise management system for a window includes an active noise control (ANC) module and a passive sound absorbing module. The ANC module is disposed in or adjacent a ventilation channel of the window and configured to substantially cancel low-frequency noise entering the ventilation channel. The passive sound absorbing module is disposed in or adjacent to the ventilation channel and configured to absorb both high-frequency noise entering the channel and harmonic sounds generated by the ANC module.

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.

A method for sound wave generation includes sensing one or more characteristics of a sound wave; calculating an inverted sound wave based on the one or more characteristics; and emitting the inverted sound wave by flowing a current, selected according to the inverted sound wave, through a wire under tension that passes through a positive pole of a magnet and a negative pole of the magnet, thereby causing the wire to vibrate. An apparatus for sound wave generation includes a microphone configured to detect one or more characteristics of a sound wave detected in a predetermined vicinity of the microphone; a processor coupled to the microphone, configured to calculate an inverted sound wave based on the one or more characteristics; a power supply; and at least one emitter module coupled to the processor, each emitter module including one or more magnets with a positive pole and a negative pole, a wire, made of a conductive material, under tension, that passes between the positive pole and the negative pole, and the power supply configured to deliver a current passing through the wire, the current selected by the processor to vibrate the wire and thereby emit the inverted sound wave.