Systems, devices, and methods are described for providing loudspeaker protection. An upstream loudspeaker model estimation component receives sensed electrical characteristics of a loudspeaker and generates an impedance model from which an excursion model, and associated parameters, of the loudspeaker as well as a gain change parameter may be generated. The impedance components are fitted to features of an estimated impedance, based on the voltage and current sense data, to generate the estimated impedance model that is converted to an excursion model of the loudspeaker. A downstream audio signal processing component, based on the excursion model, or parameters thereof, limits a predicted excursion of the loudspeaker utilizing excursion-constraining processing circuitry that includes a non-linear constraint filter. Processed audio signals associated with the limited excursion are subject to distortion suppression prior to releasing the output audio signals for playback on the loudspeaker.

A playback device includes a speaker, a controller, a first switch circuit, and a second switch circuit. The speaker has a first terminal and a second terminal. The controller is configured to output a first audio signal and a second audio signal. The controller is coupled to the first terminal of the speaker, and is configured to transmit the first audio signal to the speaker. The second switch circuit is coupled between the second terminal of the speaker and the controller, and is coupled to the first switch circuit. The second switch circuit is configured to transmit the second audio signal from the controller to the speaker when the first switch circuit is turned on.

Smart buzzer systems for apartment buildings, where an intercom station in an apartment unit notifies the user of a request from a guest to unlock the building's door, sends the user's approval of the request to the door, and enables the user and the guest to talk to each other, are disclosed. The smart buzzer systems are enhanced with connectivity with mobile devices and mobile applications as well as automation. The intercom station includes an audio input-output circuit configured to process audio signals, which includes a line input buffer configured to process audio signals from a legacy base microphone through a wiring interface for a legacy intercom system to a processor and a line output driver configured to process audio signals from the processor to the legacy base speaker through the wiring interface for the legacy intercom system.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, determining how much to attenuate the audio signal when a power level of the audio signal exceeds a threshold power level, combining the audio signal with an auxiliary attenuation signal from an auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.

An audio device includes a digital-to-analog converter, an amplifier, a speaker, a power management unit and a temperature sensor. The digital-to-analog converter is configured to convert a digital audio signal into an analog audio signal. The amplifier is coupled to the digital-to-analog converter and configured to amplify the analog audio signal and generate an amplified analog audio signal. The speaker is coupled to the amplifier and configured to broadcast the amplified analog audio signal. The power management unit is configured to provide the amplifier with a first working voltage and provide the digital-to-analog converter with a second working voltage. The temperature sensor is coupled to the speaker and configured to generate a temperature detection signal according to a temperature of the speaker. Wherein, the power management unit adjusts at least one of the first working voltage and the second working voltage according to the temperature detection signal.

An optimised method for driving a loudspeaker is used for protecting the loudspeaker from damage due to excessive excursion or from overheating. The playback power of an incoming audio data stream is compared with a feedback power derived from the loudspeaker actuator and the comparison is used to adjust the frequency response of the loudspeaker, across individual sub bands.

A control circuit for an electrostatic transducer including: an audio signal input, a detector configured to detect a current or charge signal from the electrostatic transducer. The detector is configured to produce an audio output signal varying at audio frequencies. A transform circuit is configured to transform the audio output signal to produce a feedback signal. A comparator is configured to compare an input audio signal at the audio signal input to the feedback signal to produce an error signal. A controller is configured to input a control signal to the electrostatic transducer, the control signal responsive to the error signal. The control signal is configured to control acoustic transparency of the electrostatic transducer, from outside space through through-holes of the first electrode, across the membrane and through through-holes of the second electrode.

A high sensitivity microphone may include a sound detecting module including a vibration film and a fixed film, a power source circuit supplying a power source to the sound detecting module through a switch control of a first switch applying a first bias and a second switch applying a second bias, a detecting circuit removing a noise included in a first capacitance signal and a second capacitance signal that are differential input from the sound detecting module, according to a switch control of a third switch inputting the first capacitance signal in conjunction with the first switch and a fourth switch inputting the second capacitance signal in conjunction with the second switch, and a switch controller performing a first switch mode linking the first switch and the third switch and a second switch mode linking the second switch and the fourth switch for differential input and output of the microphone.

A limiter system for an active speaker may include at least one lowpass filter configured to receive an input signal and output a signal lower than a crossover frequency, at least one highpass filter, configured to receive an input signal and output a signal higher than the crossover frequency, a first allpass filter configured to adjust the phase of the signal lower than the crossover frequency, a second allpass filter configured to adjust the phase of the signal higher than the crossover frequency, a first limiter, configured to receive and limit the signal from the first allpass filter, a second limiter, configured to receive and limit the signal from the second allpass filter, and a mixer, configured to mix the signal lower from the first limiter and the signal from the second limiter.

An aspect of the present disclosure is directed to systems, methods, and software products that enhance the sound and perception of bass energy in loudspeaker systems which have limited response in the low frequency spectrum. The systems, methods, and software products provide for (i) receiving one or more bass sub-bands of audio channel content, wherein each bass sub-band is separated from an audio program content spectrum including high-band energy; (ii) applying boost to each bass sub-band to compensate for rolloff of the speaker system; (iii) applying a limiter to prevent speaker saturation at low frequencies and/or high volume levels; and (iv) combining each bass sub-band along with the high band energy for sending as a recombined audio signal to the speaker system for rendition as physical sound.