A computer implemented method for managing a sound emitting device comprising: receiving data associated with operation of the sound emitting device at a predetermined location; processing said data to determine an operating characteristic of that device for that location; comparing the operating characteristic with a predetermined mathematical relationship to determine whether a difference exists; and identifying an input adjustment to correct the difference wherein the input adjustment optionally is within a predetermined range and optionally does not exceed a predetermined maximum increment; wherein the predetermined mathematical relationship is between an input variable and an output variable in respect of the sound emitting device.

In one aspect, an example method includes (i) presenting first media content from a first source; (ii) encountering a trigger to switch from presenting the first media content from the first source to presenting second media content from a second source; (iii) determining a first loudness level of the first media content; (iv) determining a second loudness level of the second media content; (v) based on a difference between the first loudness level and the second loudness level, adjusting a loudness level of the second media content so as to generate modified media content having a third loudness level that is different from the second loudness level; and (vi) responsive to encountering the trigger, presenting the modified media content having the third loudness level.

An audio signal processing device comprises: a receiver for receiving an input audio signal; a processor for generating loudness metadata corresponding to the input audio signal; and an outputter for transmitting the loudness metadata generated by the processor. The processor is configured to acquire loudness information analyzed from input content, acquires loudness information about the input audio signal by measuring the loudness of the input audio signal, generates the loudness metadata by converting the loudness information, and transmits, through the outputter, the generated loudness metadata to an output device for outputting the input audio signal.

In one aspect, an example method includes (i) determining, by a playback device, a first loudness level of a first portion of first media content from a first source while the playback device presents the first media content, with the first portion having a first length; (ii) switching, by the playback device, from presenting the first media content from the first source to presenting second media content from a second source; (iii) based on the switching, determining, by the playback device, second loudness levels of second portions of the first media content while the playback device presents the second media content, with the second portions having a second length that is shorter than the first length; and (iv) while the playback device presents the second media content, adjusting, by the playback device, a volume of the playback device based on one or more of the second loudness levels.

A class-D amplifier includes: a gain control unit that amplifies an input audio signal in accordance with a compensation gain to generate an input signal Vin; and a pulse width modulator that generates a first pulse Vp whose pulse width changes according to the input signal Vin within a first input range A1 where a value of the generated input signal Vin is higher than a first boundary Vb1, and that generates a second pulse Vn whose pulse width changes according to the generated input signal Vin within a second input range A2. The gain control unit controls the compensation gain so that first inclination of an input/output characteristic of the class-D amplifier in a first section in which the pulse width modulator outputs both the first pulse Vp and the second pulse Vn and second inclination of the input/output characteristic in a second section other than the first section are similar to each other.

Disclosed are a method and apparatus for improving a signal-to-noise ratio of a microphone signal. The method includes: selecting a target microphone to be improved as a first microphone, and selecting a microphone whose signal-to-noise ratio is greater than a signal-to-noise ratio of the first microphone and exceeds a preset first threshold as a second microphone; and adding, by an adder, a voice signal of the first microphone and a voice signal of the second microphone in a case that a same voice signal is inputted, to obtain a first microphone signal whose signal-to-noise ratio has been improved.

Systems and methods are provided for circuit configurations that maintain audio playback performance while reducing power consumption. In particular, a gain for a current analog-to-digital converter in an audio playback path is adjusted based on an amplitude of the input signal. Additionally, systems and methods are provided for transitioning between a modes of operation for large signals and mode of operation for small signals.

This application relates to amplifier circuitry and, in particular, to class-D amplifier circuits. The application describes amplifier circuitry (400) for receiving an input signal (Sin) and generating first and second driving signals (SoutP, SoutN) for driving a bridge-tied-load. The amplifier circuitry includes first and second class-D output stages (403p, 403n) for generating the first and second driving signals based on the input signal. A controller (406) controllably varies a common-mode component of the first and second driving signals based on an indication of amplitude of the first and second driving signals. The controller varies the common-mode component, at lower signal amplitudes, so the common-mode level of the first and second driving signals is moved away from an operating region that leads to distortion.

A system is provided to analyze frequency (or phase) modulation distortion in an audio device, which may include testing with audio frequencies. In one embodiment a change in pitch (or frequency) is measured at an output of the audio device. One or more distortion signals from the audio device may be measured for an amplitude, phase, and or frequency modulation effect. In another embodiment a musical signal may be used as a test signal. Providing additional test signals to the audio device can induce a time varying cross-modulation distortion signal (or static cross-modulation distortion signal) from an output of the audio device. Also utilizing at least one additional filter, filter bank, demodulator and or frequency converter and or frequency multiplier provides extra examination of distortion. Also frequency and or phase response can be measured with the presence of a de-sensing signal and or another signal that induce near slew rate limiting or near overload condition of the device under test. Another system is provided to analyze modulation index differences between input and output signals for a test signal including modulation.

Disclosed are systems and methods for automatic control of gain in audio and video conferencing applications to maintain a predetermined and stable audio level. In one embodiment, a first stage applies a first stage gain based on a long-term estimate of signal level, while a second stage gain, based on a short-term estimate of signal level assists the first stage gain to achieve a target level. Some embodiments of long-term level estimation utilize statistical analysis of a buffer to validate or arrive at a more accurate long-term signal level estimate.