A detection unit has a fixed magnet, which is part of a magnetic circuit unit, and also has a movable magnet and a magnetic sensor, which are disposed below a cap. A fixed magnetic field component oriented toward a vibration direction acts on the magnetic sensor due to a leakage flux from the magnetic circuit unit. A movable magnetic field component acts from the movable magnet on the magnetic sensor in a direction crossing the fixed magnetic field component. A change in the angle of a detection magnetic field component, which is a combined vector formed from the magnetic field components in two directions, is detected by the magnetic sensor. According to the output in this detection, the operational position of the movable magnet is measured.

A system for detecting parasitic oscillation in a wearable audio device that includes an electro-acoustic transducer that is configured to develop sound for a user, a housing that holds the transducer, at least one of a feedforward microphone that is configured to detect sound outside of the housing and output a feedforward microphone signal and a feedback microphone that is configured to detect sound inside of the housing and output a feedback microphone signal, and an opening in the housing that emits sound pressure from the transducer. The system includes a parasitic oscillation detector that is configured to determine a fundamental frequency of at least one of the feedforward and feedback microphone signals and compare an amplitude of the determined fundamental frequency to a threshold level, to determine parasitic oscillation.

A system includes a feedforward path coupled to a signal input. The system also includes a speaker coupled to the feedforward path. The system includes a back electromotive force (BEMF) extractor coupled to the speaker, where the BEMF extractor has a first input, a second input, and an output. The BEMF extractor includes a first summing point coupled to the first input. The BEMF extractor includes a resistor amplifier coupled to the second input and the first summing point. The BEMF extractor includes a high pass filter coupled to the second input and to an inductor amplifier. The BEMF extractor also includes a low pass filter coupled to the first summing point. The BEMF extractor includes a second summing point coupled to the low pass filter, the inductor amplifier, and the output.

Illustrative embodiments enable a MEMS transducer to quickly recover from, acoustic overload events by quickly resetting signal processing circuitry downstream from a MEMS transducer. An acoustic overload sensor detects occurrence of an acoustic overload event, and triggers a reset circuit to operate a set of switches to rapidly drain charge from a corresponding set of capacitances within the transducer, or within the signal processing circuitry, thereby resetting the signal processing circuitry more rapidly than would occur if said transducer or circuitry were allowed to recover on its own.

A virtual image display includes acoustic sensors and a controller, and a method is for operating the same. The acoustic sensors are for detecting the wind frequency information in the environment. The controller computes time points of the acoustic sensors receiving the wind frequency information, and computes wind direction information based on the time points.

Methods, systems, and media for ambient background noise modification are provided. In some implementations, the method comprises: identifying at least one noise present in an environment of a user having a user device, an activity the user is currently engaged in, and a physical or emotional state of the user; determining a target ambient noise to be produced in the environment based at least in part on the identified noise, the activity the user is currently engaged in, and the physical or emotional state of the user; identifying at least one device associated with the user device to be used to produce the target ambient noise; determining sound outputs corresponding to each of the one or more identified devices, wherein a combination of the sound outputs produces an approximation of one or more characteristics of the target ambient noise; and causing the one or more identified devices to produce the determined sound outputs.

An apparatus for processing an audio input signal having one or more audio input channels to obtain an audio output signal having one or more audio output channels has an estimation unit configured to estimate a radiation resistance of each driver of one or more drivers of each loudspeaker of one or more loudspeakers as an estimated radiation resistance; or as an estimated radiation impedance, wherein said estimated radiation impedance has estimated information on the radiation resistance of said driver; and a processing unit configured to obtain the audio output channels by processing each audio input channel depending on the estimated radiation resistance or the estimated radiation impedance of each driver of each loudspeaker. The estimation unit is configured to estimate the estimated radiation resistance or the estimated radiation impedance depending on estimated sound pressure information indicating an estimation of sound pressure at said driver of said loudspeaker, and depending on estimated velocity information indicating an estimation of a driver velocity of said driver of said loudspeaker.

An object is to provide a sound collection apparatus capable of collecting a sound with a higher SN rate than before through use of a reflected sound. The sound collection apparatus is installed in a vehicle. The vehicle includes a seat for a passenger to sit on, and a reflective structure that reflects a sound emitted by a passenger sitting in the seat. The sound collection apparatus includes a first microphone arranged at a position where a direct sound that is a sound emitted by the passenger is readily collected, and a second microphone arranged at a position where a reflected sound that is a sound emitted by the passenger and reflected by the reflective structure is readily collected.

A system for detecting parasitic oscillation in a wearable audio device that includes an electro-acoustic transducer that is configured to develop sound for a user, a housing that holds the transducer, at least one of a feedforward microphone that is configured to detect sound outside of the housing and output a feedforward microphone signal and a feedback microphone that is configured to detect sound inside of the housing and output a feedback microphone signal, and an opening in the housing that emits sound pressure from the transducer. The system includes a parasitic oscillation detector that is configured to determine a fundamental frequency of at least one of the feedforward and feedback microphone signals and compare an amplitude of the determined fundamental frequency to a threshold level, to determine parasitic oscillation.

In an active noise reducing headphone, a signal processor applies filters and control gains of both the feed-forward and feedback active noise cancellation signal paths. The signal processor is configured to apply first feed-forward filters to the feed-forward signal path and apply first feedback filters to the feedback signal path during a first operating mode providing effective cancellation of ambient sound, and to apply second feed-forward filters to the feed-forward signal path during a second operating mode providing active hear-through of ambient sounds with ambient naturalness.