Abstract: An adaptive filter converts time domain samples of an input signal into frequency domain signals, dynamically adjusts a stability conditional number based on the frequency domain signals, and uses the dynamically adjusted stability conditional number to control step size normalization during adaptation of frequency domain coefficients of the adaptive filter. The stability control number may be global to a range of frequency bins based on a peak magnitude of the input signal and/or may be frequency bin-specific stability control numbers based on corresponding frequency bin-specific error signal magnitudes. The adaptive filter also dynamically adjusts a noise floor based on the frequency domain input signals and refrains from updating frequency domain coefficients when a magnitude of the frequency domain input signal associated with a frequency bin is greater than the dynamically adjusted noise floor.

Abstract: This application relates to audio driving circuitry (100), and in particular to audio driving circuitry for outputting first and second audio driving signals for driving a stereo audio load (106), which may be a stereo audio load of an accessory apparatus (102) removably coupled to the audio driving circuitry in use. A load monitor (111) is provided for monitoring to monitor, from a monitoring node (112), an indication of a common mode return current passing through a common return path, together with an indication of a common mode component of the first and second audio driving signals and to determine an impedance characteristic of the stereo audio load. The load monitor (111) can provide dynamic monitoring of any significant change in load impedance. In some embodiments the load monitor (111) comprises an adaptive filter (301) which adapts a parameter of the filter which is related to the load impedance so as to determine the indication of load impedance.

Abstract: A system for evaluating an ear seal between an earphone of a hearing device and an ear canal includes a first transducer that plays sound in response to an electrical signal that includes a reference frequency component and a test frequency component lower than the reference frequency. A second transducer receives the sound in the ear canal. A controller is configured to: calculate at least one electrical signal level difference between the electrical signal reference and test frequency components, measure acoustical levels of the reference and test frequency components of the sound in the ear canal, calculate an acoustical signal level difference between the measured acoustical levels of the reference and test frequency components, calculate a normalized acoustical difference value by subtracting the electrical signal level difference from the acoustical signal level difference, and determine a measurement of the ear seal based on the normalized acoustical difference value.

Abstract: A system may include a resistive-inductive-capacitive sensor, a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor and configured to at a plurality of periodic intervals, measure phase information associated with the resistive-inductive-capacitive sensor and based on the phase information, determine a displacement of a mechanical member relative to the resistive-inductive-capacitive sensor. The system may also include a driver configured to drive the resistive-inductive-capacitive sensor at a driving frequency and a driving amplitude, wherein at least one of the driving frequency and the driving amplitude varies among the plurality of periodic intervals.

Abstract: A method of speaker verification comprises receiving an audio signal representing speech. While the audio signal is being received, features of the received audio signal are extracted. The extracted features, of at least a part of the received audio signal corresponding to the speech of at least one speaker, are summarised, and the summarised extracted features are stored. In response to a request for a speaker verification process relating to at least one enrolled user, the speaker verification process is performed using the previously summarised features.

Abstract: MEMS devices comprise a filter configured and arranged to inhibit the entry of particles into at least a region of the interior of the substrate cavity from a region underlying the substrate.

Abstract: Methods and apparatus for digital signal processing of signals received from sensors are provided. A first input signal and a second input signal are received. A noise correlation statistic between the first input signal and the second input signal is estimated. An inter sensor signal model representative of a relationship between desired signal components present in the first input signal and the second input signal is estimated. Responsive to the noise correlation statistic meeting a predefined condition, estimating the inter sensor signal model is based on the noise correlation statistic. Responsive to the noise correlation statistic not meeting the predefined condition, estimating the inter sensor signal model is based on a constrained noise correlation statistic derived from the noise correlation statistic.

Abstract: A data acquisition system may include an input for receiving an input signal for the data acquisition system, a plurality of data paths including a first data path and a second data path, and a signal estimator configured to determine a magnitude of the input signal using estimation of the input signal and dynamically deactivate one of the first and second data paths based on the magnitude of the input signal.

Abstract: A multi-microphone algorithm for detecting and differentiating interference sources from desired talker speech in advanced audio processing for smart home applications is described. The approach is based on characterizing a persistent interference source when sounds repeated occur from a fixed spatial location relative to the device, which is also fixed. Some examples of such interference sources include TV, music system, air-conditioner, washing machine, and dishwasher. Real human talkers, in contrast, are not expected to remain stationary and speak continuously from the same position for a long time. The persistency of an acoustic source is established based on identifying historically-recurring inter-microphone frequency-dependent phase profiles in multiple time periods of the audio data. The detection algorithm can be used with a beamforming processor to suppress the interference and for achieving voice quality and automatic speech recognition rate improvements in smart home applications.

Abstract: An acoustic testing apparatus may include connections for multiple devices under test (DUTs) to support simultaneous testing of two or more miniature electroacoustic devices. The acoustic testing apparatus may allow the testing of multiple DUTs with a ratio of less than one reference microphone per DUT. Thus, the speed of testing DUTs may be increased without adding significant cost through additional reference microphones. For example, a single reference microphone may be used to test two or four DUTs coupled together through an acoustic test cavity.

Abstract: A system may include a forward signal path having a forward gain and configured to receive an input signal at an input and generate an output signal at an output as a function of the input signal, a feedback signal path having a feedback gain and coupled between the output and the input, and a control subsystem configured to operate the forward signal path and the feedback signal path in at least two modes comprising a first mode in which the forward gain is a first forward gain and the feedback gain is a first feedback gain and a second mode in which the forward gain is a second forward gain smaller than the first forward gain and the feedback gain is a second feedback gain larger than the first feedback gain. The control subsystem may cause operation in the first mode when signal content is present in the input signal and may cause operation in the second mode when signal content is absent from the input signal.

Abstract: A driver system may include a first n-type field-effect transistor coupled at its non-gate terminals between an output of the driver system and a first terminal of a supply voltage and configured to drive the output when the first n-type field-effect transistor is activated, a second n-type field-effect transistor coupled at its non-gate terminals between an output of the driver system and a second terminal of the supply voltage and configured to drive the output when the second n-type field-effect transistor is activated, a high-side capacitor coupled to the output of the driver system, and a low-side capacitor coupled to the second terminal of the supply voltage, wherein the high-side capacitor and the low-side capacitor are configured to track and correct for mismatches between a first resistance of the first n-type field-effect transistor and a second resistance of the second n-type field-effect transistor.

Abstract: A method for use in a biometric process, comprising: with a headset in a known acoustic environment, applying an acoustic stimulus at a first transducer of the headset; receiving a response signal at a second transducer of the headset, the response signal comprising a component of the acoustic stimulus reflected at an obstacle in the acoustic path of the first transducer; determining a condition of the headset based on the response signal; and performing the biometric process based on the determined condition.

Abstract: A method for generating an acoustic stimulus for use in an ear biometric process on a user, the method comprising: receiving an indication of stimulation frequencies for use in the ear biometric process; grouping the stimulation frequencies into bands of a psychoacoustic scale; generating the acoustic stimulus, the acoustic stimulus comprising a masked bandpass component within each band of the psychoacoustic scale that comprises one or more of the stimulation frequencies.

Abstract: A power delivery system may include a power converter configured to electrically couple to a power source and further configured to supply electrical energy to one or more loads electrically coupled to an output of the power converter, and control circuitry configured to select a constraint factor from a plurality of different constraint factors based on at least one of an input voltage to the power converter and a power level available to the power converter, and control the power converter in accordance with the constraint factor.

Abstract: There is provided a flexible membrane for use in a microelectromechanical transducer, the flexible membrane comprising an electromagnetic waveguide. There is further provided a microelectromechanical system comprising a substrate which comprises the flexible membrane, and a process for forming the flexible membrane. The flexible membrane may be configured to operate within an optical microphone system.

Abstract: The application describes a package substrate for a MEMS transducer package having a recessed region formed in an upper surface of the package substrate. The recessed region extends only partially through the package substrate from an opening in the upper surface of the package substrate in a first direction towards the lower surface of the substrate. The recessed region extends only partially through the package substrate from an opening in a side surface of the package substrate in a second direction towards an opposite side surface.

Abstract: The present disclosure relates to voltage regulator circuitry comprising an input for receiving a supply voltage, an output for outputting an output voltage, and control circuitry configured to receive a reference voltage. The voltage regulator circuitry is selectively operable in either a closed-loop mode in which the control circuitry receives a voltage indicative of the output voltage such that the voltage regulator circuitry regulates the output voltage based on the voltage indicative of the output voltage and the reference voltage received by the control circuitry or an open-loop mode in which the control circuitry does not receive the voltage indicative of the output voltage and the voltage regulator circuitry regulates the output voltage based on the reference voltage received by the control circuitry.

Abstract: A system may include a sensor configured to output a sensor signal indicative of a distance between the sensor and a mechanical member associated with the sensor, a measurement circuit communicatively coupled to the sensor and configured to determine a physical force interaction with the mechanical member based on the sensor signal, and a compensator configured to monitor the sensor signal and to apply a compensation factor to the sensor signal to compensate for changes to properties of the sensor based on at least one of changes in a distance between the sensor and the mechanical member and changes in a temperature associated with the sensor.

Abstract: This application relates to time-encoding modulators (TEMs). A TEM receives an input signal (SIN) and outputs a time-encoded output signal (SOUT). A filter arrangement receives the input signal and also a feedback signal (SFB) from the TEM output, and generates a filtered signal (SFIL) based, at least in part, on the feedback signal. A comparator receives the filtered signal and outputs a time-encoded signal (SPWM) based at least in part on the filtered signal. The time encoding modulator is operable in a first mode with the filter arrangement configured as an active filter and in a second mode with the filter arrangement configured as a passive filter. The filter arrangement may include an op-amp, capacitance and switch network. In the first mode the op-amp is enabled, and coupled with the capacitance to provide the active filter. In the second mode the op-amp is disabled and the capacitance is coupled to a signal path for the feedback signal to provide a passive filter.