A pressure sensor of an embodiment includes a support portion, a transformable membrane part and a sensor portion. The membrane part includes an end portion supported by the support portion, and a first area and a second area. The first area is positioned between a center of the membrane part and the end portion and has a first rigidity. The second area is positioned between the first area and the end portion, and has a second rigidity lower than the first rigidity. The sensor portion is provided at the first area and includes a first magnetic layer, a second magnetic layer and a first intermediate layer provided between the first magnetic layer and the second magnetic layer. An end-side distance between the first area and the end portion is shorter than a center-side distance between the second area and the center of the membrane part.

A noise control system for a ducted rotor assembly, the ducted rotor assembly including a hub, a duct, and two or more blades coupled to the hub and supported by the duct. The noise control system including a microphone configured to receive a sound input generated by the ducted rotor assembly, the microphone configured for association with the hub; a speaker unit configured to generate a cancellation noise, the speaker configured for association with the hub; and a controller operably connected to the microphone and the speaker unit, the controller configured to selectively adjust harmonics of the cancellation noise to reduce an acoustic signature of the ducted rotor assembly. In another aspect, there is provided a rotorcraft with a ducted rotor assembly in a tail portion including a noise control system. In a third aspect, there is a method of reducing an acoustic signature of a ducted rotor assembly.

A sound masking device comprises a housing having an open end, a white noise generator within the housing, and a speaker to receive a white noise signal from the white noise generator and to emit a white noise corresponding to the white noise signal. The speaker is set back from the open end and positioned within the housing to emit the white noise toward the open end. The housing may comprise a shelf or shoulder around an inner surface of the housing located between the speaker and the open end.

The various implementations described herein include methods, devices, and systems for calibrating LED(s). In one aspect, an electronic device includes: (1) a plurality of light emitting diodes (LEDs); (2) one or more processors; and (3) memory storing a plurality of color correction matrices, each color correction matrix of the plurality of color correction matrices: (a) corresponding to an LED of the plurality of LEDs, (b) generated based on a desired color value for the corresponding LED, and (c) scaled to prevent overrange of color values for the corresponding LED; and the memory includes instructions for operating the plurality of LEDs in accordance with the stored plurality of color correction matrices.

Embodiments of the invention relate to methods, apparatus and systems for biometric authentication based on an audio signal, wherein the audio signal comprises a representation of a voice signal of a user conducted via at least part of a user's skeleton. Further embodiments of the disclosure may relate to biometric authentication based upon a combination of a bone-conducted audio signal, or a bone-conducted voice biometric process, with an air-conducted voice signal.

A system for monitoring a building having one or more microphones coupled to a telephone includes a detector configured to detect a triggering event within the building and transmit an activating signal when the triggering event is detected, and a control module configured to receive the activating signal from the detector. The control module is programmed to activate at least one of the one or more microphones to monitor sound when the activating signal is received.

According to an embodiment, a circuit includes a high- resistor including a plurality of semiconductor junction devices coupled in series and a plurality of additional capacitances formed in parallel with the plurality of semiconductor junction devices. Each semiconductor junction device of the plurality of semiconductor junction devices includes a parasitic doped well capacitance configured to insert a parasitic zero in a noise transfer function of the high- resistor. Each additional capacitance of the plurality of additional capacitances is configured to adjust a parasitic pole in the noise transfer function of the high- resistor in order to compensate for the parasitic zero.

Systems, methods, and devices for implementing an audio assisted dynamic barcode system. A gate validation system may include a barcode reader, a speaker, and a processor configured to perform operations including receiving, using the barcode reader, a first barcode from a portable electronic device indicating a request for passage through a gate. The operations may also include outputting, using the speaker, an audio signal having a predetermined feature. The operations may further include receiving, using the barcode reader, a second barcode from the portable electronic device indicating a detected feature of the audio signal. The operations may further include determining that the detected feature matches the predetermined feature and, in response to determining that the detected feature matches the predetermined feature, facilitating passage of a holder of the portable electronic device through the gate.

Systems, methods, and devices for determining a frequency of a received audio signal. A device may include a microphone, a speaker, and a processor configured to perform operations including receiving, using the microphone, a first audio signal having a predetermined frequency. The operations may also include, for each test frequency of a plurality of test frequencies and for each test phase of a plurality of test phases, generating a second audio signal having the test frequency and the test phase, outputting, using the speaker, the second audio signal, receiving, using the microphone, a combined audio signal being a combination of the first audio signal and the second audio signal, determining an amplitude of the combined audio signal, and determining that the predetermined frequency is within a threshold range of the test frequency when the amplitude of the combined audio signal is below a threshold.

An image capture device includes a housing having a pattern of apertures and a membrane assembly. The membrane assembly includes a support that has internal and external surfaces and a channel that aligns with at least one aperture of the pattern of apertures and extends between the internal and external surfaces. The membrane assembly includes indents that are adjacent to the channel, aligned with the pattern of apertures, and disposed on the external surface. The indents have a depth that is less than a depth of the channel.