Analog Devices Global

Knowles Electronics, Inc.

Kasper Strange

Kim Spetzler Berthelsen

Henrik Thomsen

Andrzej Pawlowski

Robert W Adams

Miguel Alejandro Chavez Salas

The disclosure relates to a microphone assembly including a multibit analog-to-digital converter configured to generate N-bit samples representative of a microphone signal. The microphone assembly also includes a first digital-to-digital converter configured to generate a corresponding M-bit digital signal based on N-bit digital samples, wherein N and M are positive integers and N&#x3e;M. The microphone assembly may include a data interface configured to repeatedly receive samples of the M-bit digital signal and write bits of the M-bit digital signal to a data frame.

Microphone assembly with pulse density modulated signal

A method of estimating diaphragm excursion of an electrodynamic loudspeaker may be performed using audio signals. An audio output signal may be applied to a voice coil of the electrodynamic loudspeaker through an output amplifier to produce sound. A detected voice coil current and a determined voice coil voltage may be applied to a linear adaptive digital loudspeaker model that has a plurality of adaptive loudspeaker parameters. The parameter values of the adaptive loudspeaker parameters may be computed based on the linear adaptive digital loudspeaker model and applied to a non-linear state-space model of the electrodynamic loudspeaker. For the non-linear state-space model, a predetermined non-linear function may be applied to at least one of the plurality of received parameter values to compute at least one non-linearity compensated parameter value of the adaptive loudspeaker parameters, to determine an instantaneous excursion of the diaphragm.

Method of estimating diaphragm excursion of a loudspeaker

The disclosure relates to a microphone assembly comprising a multibit analog-to-digital converter configured to receive, sample, and quantize a microphone signal to generate N-bit digital microphone samples representative of the microphone signal at a first sampling frequency. The microphone assembly also comprises a first digital-to-digital converter configured to receive, quantize, and noise-shape the N-bit digital microphone samples to generate a corresponding M-bit Pulse Density Modulated (PDM) signal, wherein N and M are positive integers, and N&#x3e;M. The microphone assembly may comprise a SoundWire compliant data interface configured to repeatedly receive samples of the M-bit PDM signal and write bits of the M-bit PDM signal to a SoundWire data frame.

The present application relates in one aspect to a method of controlling diaphragm excursion of an electrodynamic loudspeaker. The method comprises dividing the audio input signal into at least a low-frequency band signal and a high-frequency band signal by a band-splitting network and applying the low-frequency band signal to a diaphragm excursion estimator. The instantaneous diaphragm excursion is determined based on the low-frequency band signal. The determined instantaneous diaphragm excursion is compared with an excursion limit criterion. The low-frequency band signal is limited based on a result of the comparison between the instantaneous diaphragm excursion and the excursion limit criterion to produce a limited low-frequency band signal which is combined with the high-frequency band signal to produce an excursion limited audio signal.

Method of controlling diaphragm excursion of electrodynamic loudspeakers

A feedback cancellation assembly for an electroacoustic communication apparatus may include a signal transmission path for generation and emission of an outgoing sound signal to an external environment through an electrodynamic loudspeaker and a signal reception path comprising a microphone for generation of a microphone input signal corresponding to sound received from the external environment. The signal reception path may generate a digital microphone signal. The outgoing sound signal may be acoustically coupled to the microphone. An electronic feedback cancellation path may be coupled between a tapping node and a summing node to produce a feedback cancellation signal to the summing node.

Echo cancellation methodology and assembly for electroacoustic communication apparatuses

The present invention relates in one aspect to a voice coil temperature protector for electrodynamic loudspeakers. The voice coil temperature protector comprises an audio signal input for receipt of an audio signal supplied by an audio signal source and a probe signal source for generation of a low-frequency probe signal. A signal combiner is configured to combine the audio signal with the low-frequency probe signal to provide a composite loudspeaker drive signal comprising an audio signal component and a probe signal component. The voice coil temperature protector comprises a current detector configured for detecting a level of a probe current component flowing through the voice coil in response to the composite loudspeaker drive signal and a current comparator which is configured to comparing the detected level of the probe current component with a predetermined probe current threshold. The predetermined probe current threshold corresponds to a predetermined voice coil temperature via a known temperature dependency of a voice coil resistance. The voice coil temperature protector further comprises a signal controller configured for attenuating a level of the audio signal in response to the probe current component falls below the predetermined probe current threshold.

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Copenhagen, Denmark

Kasper Strange