Methods and systems for performing automatic speed-based audio control. One method includes receiving, with an electronic control unit included in a vehicle, a speed of the vehicle and receiving, with the electronic control unit, an audio signal. The method also includes accessing, with the electronic control unit, a plurality of equalization curves based on the speed of the vehicle, each of the plurality of equalization curves associated with the speed of the vehicle and each of the plurality of equalization curves defining a gain adjustment for one of a plurality of frequencies, and, for each curve of the plurality of equalization curves, applying the gain adjustment defined by the curve to one of the plurality of frequencies of the audio signal.

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.

Doherty radio frequency (RF) amplifier circuitry includes an input node, an output node, a main amplifier path, and a peaking amplifier path. The main amplifier path is coupled between the input node and the output node and includes a main amplifier. The peaking amplifier path is coupled in parallel with the main amplifier path between the input node and the output node, and includes a peaking amplifier and a peaking variable gain preamplifier between the input node and the peaking amplifier. The peaking variable gain preamplifier is configured to adjust a current provided to the peaking amplifier.

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.

A signal processing circuit includes a signal path for outputting a first signal included in an input signal from a first output terminal to another signal processor; branch paths one of which extends from a top position located at a position on the signal path and the others which extend from associated branch positions that divide the signal path starting from the top position to the first output terminal into segments in each of which a first amount of delay obtained by equally dividing an amount of delay caused by the signal path and that is added to the first signal; a switch connected to each of the branch paths and switches whether to allow a second signal other than the first signal included in the input signal to pass through the connected branch paths; a variable gain amplifier connected to each of the switches and amplifies the second signal.

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 method and apparatus for measuring a biopotential signal together with impedance changes uses electrodes on a subject’s skin and for compensating for such impedances to increase accuracy and usability of such devices for short-and long-term monitoring of biosignals. The apparatus can include a first terminal for connection to a first electrode, a second terminal for connection to a second electrode, a first circuitry configured for measuring the biopotential signal from the first and the second terminal, a third terminal for connection to the reference skin electrode, a first variable controlled resistance load connected to the first terminal, and a second variable controlled resistance load connected to the second terminal.

A method and apparatus for measuring a biopotential signal together with impedance changes uses electrodes on a subject’s skin and for compensating for such impedances to increase accuracy and usability of such devices for short-and long-term monitoring of biosignals. The apparatus can include a first terminal for connection to a first electrode, a second terminal for connection to a second electrode, a first circuitry configured for measuring the biopotential signal from the first and the second terminal, a third terminal for connection to the reference skin electrode, a first variable controlled resistance load connected to the first terminal, and a second variable controlled resistance load connected to the second terminal.

A high-frequency (HF) driver circuit for an acousto-optical component includes an HF power amplifier connected to a voltage regulator for supply with a supply voltage and a bias voltage generator connected to an input of the HF power amplifier via a switch. The HF driver circuit can include a measurement device configured to measure a temperature of the HF power amplifier and a compensation device configured to control the bias voltage generator according to the temperature. The bias voltage generator is configured to provide a bias voltage to the HF power amplifier. By switching in the bias voltage, the HF power amplifier can be adjusted to a low quiescent current. By switching off the bias voltage, the HF power amplifier can be very rapidly and effectively blocked. As a result, very rapid switching-on and switching-off times, e.g., in a range of 10 to 50 ns, can be achieved.

The invention is an apparatus used to send sound exterior to the vehicle to a location on the interior of a vehicle which corresponds with the sound’s external location. The apparatus adjusts for gain by frequency and shifts frequencies of the audio signals received exterior to the vehicle to generate a modified audio signal. The adjustments include compensation for hearing loss, compensation for audio in the interior of the vehicle, and attenuation adjustments for unwanted exterior noise. The modified audio signal is generated by filtering unwanted audio from the exterior audio, adjusting for gain by frequency and shifting/compressing frequencies according to hearing deficiencies, and adjusting for gain by frequency according to audio in the interior of the vehicle. The modified audio signal may be limited to a maximum gain and then amplified in the interior of the vehicle.