A method for eliminating unstable noise is provided and applicable to a sound recording device and implemented by a codec. The method includes: activating the sound recording device to start recording; setting a suppression duration and a cutoff frequency switching duration according to unstable noise and a DC offset value of the sound recording device; processing a front-end audio of a recorded sound by a filter having a first cutoff frequency to make the unstable noise in the front-end audio quickly converge, and outputting a filtered audio signal; suppressing the filtered audio signal according to the suppression duration to eliminate the unstable noise; and adjusting the first cutoff frequency of the filter to a second cutoff frequency according to the cutoff frequency switching duration, where the first cutoff frequency is greater than the second cutoff frequency. A device for eliminating unstable noise is also provided.

An apparatus for amplifying an audio source includes a speaker and a chip. The chip includes a processor configured to generate a signal and an amplifier element configured to amplify the signal into an amplified signal. The chip further includes a current monitor configured to monitor the current of the amplified signal prior to the amplified signal being output from the chip to the speaker and a voltage monitor configured to monitor the voltage of the amplified signal prior to the amplified signal being output from the chip to the speaker. The processor of the chip is configured to control a power of the amplified signal output from the chip to the speaker based at least on the current and the voltage.

An acoustic apparatus includes a class-D amplifier including a current feedback circuit, and a speaker system including a voice coil driven by the class-D amplifier. The speaker system is configured such that, in a case where the speaker system is driven by an ordinary amplifier having a first output resistance lower than a second output impedance of the class-D amplifier, a Q factor of the speaker system falls below a predetermined lower limit of an ordinary Q factor range of an ordinary speaker system. The current feedback circuit is configured to increase the second output impedance of the class-D amplifier by feeding a current flowing to the voice coil back to an input of the class-D amplifier so as to increase a Q factor as the acoustic apparatus higher than the predetermined lower limit of the ordinary Q factor range and within the ordinary Q factor range.

A virtual reality (VR), augmented reality (AR) and/or mixed reality (MR) system in a physical environment with a plurality of loudspeakers includes a user-worn head mounted display (HMD), a VR/AR/MR processor, and a VR/AR/MR user tracking processor. The HMD includes a microphone and a user tracking device configured to track a user orientation and position. The VR/AR/MR processor delivers a digital video signal to the head-mounted display, and a digital control signal and a digital audio signal to a receiver/preamplifier. The VR/AR/MR user tracking processor receives user tracking data from the HMD user tracking device and provides a digital user tracking data signal to the receiver preamplifier. the receiver/preamplifier receives the digital user tracking data signal, the digital control signal, the digitized microphone signal, and the digital audio signal, and provides a processed audio signal to the amplifier. An amplifier receives the processed audio signal and provides amplified audio signals.

An improved method of providing high burst power to audio amplifiers from limited power sources, using parallel power paths to increase system efficiency without need for a power path controller, thus utilizing a simplified circuit operation and maximizing average power available for both the amplifier and supporting circuitry.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, multiplying the received audio signal with a power feedback signal to create a product audio signal, wherein the feedback signal comprises a low-pass filtered signal, applying a power amplifier to the product audio signal, and providing the amplified product audio signal as an output signal to a speaker.

Apparatus, systems, articles of manufacture, and methods for volume adjustment are disclosed herein. An example method includes collecting data corresponding to a volume of an audio signal as the audio signal is output through a device, when an average volume of the audio signal does not satisfy a volume threshold for a specified timespan, determining a difference between the average volume and a desired volume, and applying a gain to the audio signal to adjust the volume of the audio signal to the desired volume, the gain determined based on the difference between the average volume and the desired volume.

A driving circuit of a loudspeaker includes a periodic signal generation circuit, a signal processing circuit, a class-D amplifier circuit, a current sensing circuit, and a sample and hold circuit. The periodic signal generation circuit is arranged to generate a periodic signal and a control signal. The signal processing circuit is coupled to the periodic signal generation circuit, and is arranged to generate a pre-driving signal. The class-D amplifier circuit is coupled to the signal processing circuit, and is arranged to drive the loudspeaker according to the pre-driving signal. The current sensing circuit is coupled to the class-D amplifier circuit, and is arranged to generate a current sensing signal. The sample and hold circuit is coupled to the periodic signal generation circuit and the current sensing circuit, and is arranged to sample and hold the current sensing signal according to the control signal, to generate a current sampling signal.

The speaker coil in a dynamic speaker in a mobile computing device can be used to generate radio frequency (RF) signals having a frequency of about 100 kHz or greater. A speaker amplifier drives the dynamic speaker to produce sound and RF circuitry drives the speaker amplifier to generate the RF signals having a frequency of about 100 kHz or greater. The speaker coil can comprise a tap at an appropriate point between the ends of the coil to cause the coil to operate at resonance over a desired RF frequency band. A low-pass filter can be positioned at the speaker amplifier output to protect the speaker amplifier from RF energy generated by the RF circuitry and a high-pass filter can be positioned at the output of the RF circuitry to protect the RF circuitry from audio energy generated by the speaker amplifier.

One example includes a differential amplifier, a voltage weighting element, coupled to a voltage source which provides an input voltage, to provide a reference voltage with a constant power limit when the input voltage varies, an error amplifier configured to receive and compare the reference voltage provided from the voltage weighting element and a feedback sensed voltage provided from the differential amplifier to identify whether the sensed voltage exceeds the reference voltage, and a pulse width modulation (PWM) controller, coupled to a power transformer and the error amplifier, that reduces a transformer input current provided to the power transformer based on the comparison of the reference voltage from the voltage weighting element and the feedback sensed voltage from the differential amplifier.