Abstract: The systems, devices, and methods provided herein can be used with an audio source to automatically attenuate a signal from the audio source in response to information about a local environment. In an example, an attenuation network circuit can be used to provide automatic or “hands-free” adjustment of a headphone or headset volume level to compensate for changing background sound or noise levels. In relatively noisy environments, the attenuation network can provide little or no attenuation of an audio source signal, and in less noisy environments, the attenuation network can provide greater attenuation of the audio source signal.

Abstract: The systems, devices, and methods provided herein can be used with an audio source to automatically attenuate a signal from the audio source in response to information about a local environment. In an example, an attenuation network circuit can be used to provide automatic or “hands-free” adjustment of a headphone or headset volume level to compensate for changing background sound or noise levels. In relatively noisy environments, the attenuation network can provide little or no attenuation of an audio source signal, and in less noisy environments, the attenuation network can provide greater attenuation of the audio source signal.

Abstract: A triangular wave generator, comprising: a first frequency divider, for utilizing a first positive integer to divide a first frequency of a first periodical signal to generate a first frequency-divided signal; a second frequency divider, for utilizing a second positive integer to divide a second frequency, which equals the first frequency multiplying a third positive integer, of a second periodical signal to generate a second frequency-divided signal; and an up/down counter, for generating a triangular wave first and second frequency-divided frequencies respectively belonging to first and second frequency divided signals; wherein a frequency of the triangular wave equals to the first frequency-divided frequency, and an amplitude of the triangular wave is determined according to a ratio of the first and second frequency-divided frequencies.

Abstract: An audio codec and a BIST method adapted for the audio codec are provided. The BIST method includes the following steps. A first channel digital-to-analog converter (DAC) of the audio codec converts a test signal into an analog signal. A first channel analog-to-digital converter (ADC) of the audio codec converts the analog signal into a digital signal. Use a second channel DAC of the audio codec and a second channel ADC of the audio codec to calculate the magnitudes of a plurality of spectral components of the DFT of the digital signal. Determine whether the audio codec passes the test according to the magnitudes of the spectral components.

Abstract: An audio codec and a BIST method adapted for the audio codec are provided. The BIST method includes the following steps. A first channel digital-to-analog converter (DAC) of the audio codec converts a test signal into an analog signal. A first channel analog-to-digital converter (ADC) of the audio codec converts the analog signal into a digital signal. Use a second channel DAC of the audio codec and a second channel ADC of the audio codec to calculate the magnitudes of a plurality of spectral components of the DFT of the digital signal. Determine whether the audio codec passes the test according to the magnitudes of the spectral components.