An audio playback path of an audio apparatus includes a digital modulator, a digital-to-analog converter (DAC), and a power amplifier. The digital modulator receives a playback signal corresponding to playback audio content and generates a digital input signal in accordance with the playback signal. The DAC receives the audio input signal and generates an analog preamplifier signal. The power amplifier generates an audio output signal in accordance with the preamplifier signal and an analog attenuation determined by the analog attenuation signal. The apparatus may include a volume control input to receive a volume control signal and a playback controller configured to perform operations including generating an analog attenuation signal in accordance with the volume control signal, monitoring a playback state indicated by the playback parameters, and responsive to detecting the playback state satisfying the playback criterion, modifying a selected playback parameter to improve a performance parameter of the playback path.

A speaker and a microphone are provided to a helmet main body. A phase of a sound signal passing through a high pass filter is controlled by a first phase control section, and is amplified by a first amplification section. A phase of a sound signal passing through the low pass filter is controlled by a second phase control section, and is amplified by a second amplification section. These sound signals are synthesized by a synthesis section. A drive section drives the speaker according to a synthesized sound signal. A control section switches phase inversion processing/non-inversion processing of the phase control sections and controls an amplification factor of the amplification sections based on sound power of the sound signal.

A volume control device controls reproduced sound levels at the listening position set to the seat in the vehicle compartment, and gives the phase difference to an externally inputted sound signal, and supplies the sound signals to two speakers. Here, the phase difference is calculated, at a frequency lower than a predetermined frequency, for sound signals reproduced by the speakers in front of and behind the listening position. Also, the phase difference is calculated to make a reproduced sound level at the listening position smaller than the reproduced sound level when the sound signal is reproduced by either one of the pair of speakers. Preferably, the listening position includes two evaluation points, and the reproduced sound level at the listening position is a sum of the reproduced sound levels at the two evaluation points. Thus, the reproduced sound may become small at an arbitrary listening position in the acoustic space.

The present invention relates in one aspect to an audio amplification circuit comprising an input terminal for receipt of an input signal from a transducer. A signal processor is operatively coupled to the input terminal for receipt and processing of the input signal to generate a processed digital audio signal in accordance with a programmable configuration setting of the signal processor. A serial data transmission interface is configured for receipt of the processed digital audio signal and supply of a corresponding digital audio stream at an output terminal of the integrated audio amplification circuit. A serial data receipt interface is operatively coupled to an externally accessible configuration terminal of the integrated audio amplification circuit and a controller is configured to adjust one of the programmable configuration setting of the signal processor and a format of a digital audio stream in accordance with first configuration data received through the serial data receipt interface. The controller is in a first state is responsive to a logic state of the externally accessible configuration terminal to control the format of the digital audio stream or the programmable configuration setting. In a second state, the controller is configured for receipt and reading of the first configuration data through the externally accessible configuration terminal and the serial data receipt interface.

An earphone line control device includes a power supply management unit, a filter unit, a switching circuit and a control unit. The switching circuit includes a switch in series with a resistance, a first end of the power supply management unit and an end of the filter unit are both connected to a power supply, a second end of the power supply management unit is connected to a first end of the control unit, the other end of the filter unit is connected to a second end of the control unit, a third end of the power supply management unit is connected to ground, a third end of the control unit is connected to ground, an end of the resistance is connected to the power supply, the other end of the resistance is in series with an end of the switch and connected to a fifth end of the control unit, and the other end of the switch is connected to a forth end of the control unit. When the switch is turned off, the control unit outputs a preset coded pulse signal.

In accordance with an embodiment, a method includes determining an amplitude of an input signal provided by a capacitive signal source, compressing the input signal in an analog domain to form a compressed analog signal based on the determined amplitude, converting the compressed analog signal to a compressed digital signal, and decompressing the digital signal in a digital domain to form a decompressed digital signal. In an embodiment, compressing the analog signal includes adjusting a first gain of an amplifier coupled to the capacitive signal source, and decompressing the digital signal comprises adjusting a second gain of a digital processing block.

The invention relates to a method for rendering ultrasonic signals audible that is characterized in that the temporal dynamic range of the ultrasonic signal is maintained. The amplitude profile of the ultrasonic signal picked up in the time domain remains unaltered. The frequency shift from the ultrasonic range to the audible range is possible up to a factor of 32 using the present invention.

An audio processing system includes a server complex in communication with a network. The server complex receives a digital audio file and one or more analog domain control settings from a client device across the network. A digital-to-analog converter converts the digital audio file to an analog signal. One or more analog signal processors apply at least one analog modification to the analog signal in accordance with the one or more analog domain control settings. An analog-to-digital converter converts the modified analog signal to a modified digital audio file. The server complex can then deliver the modified digital audio file to the client device across the network.

An element of an automatic gain control system that automatically calibrates a Composite Gain vs Ambient Noise look-up table responsive to user zone gain inputs at various ambient noise levels. The table is a graph of adjacent (horizontally or diagonally) data points (nodes) mapping ambient noise to composite gain. Three algorithmic rules determine position changes of the nodes responsive to zone gain inputs. A curve may be fit to an arrangement of adjacent nodes. The curve, or the interpolated table value, is used with an ambient noise input to determine the current composite gain. The element may be used with many traditional ANC systems. Once calibrated over the full range of ambient noises in the user's space, the ANC system may never need further user zone gain inputs.

A voice aware audio system and a method for a user wearing a headset to be aware of an outer sound environment while listening to music or any other audio source. An adjustable sound awareness zone gives the user the flexibility to avoid hearing far distant voices. The outer sound can be analyzed in a frequency domain to select an oscillating frequency candidate and in a time domain to determine if the oscillating frequency candidate is the signal of interest. If the signal directed to the outer sound is determined to be a signal of interest the outer sound is mixed with audio from the audio source.