Apparatuses and methods are described to identify desired audio. A first input of an apparatus is configured to receive a main signal. A second input of the apparatus is configured to receive a reference signal. A normalizer is configured to normalize a compressed main signal by a compressed reference signal to create a normalized main signal. A single channel normalized voice threshold comparator is configured to receive as an input the normalized main signal and to output a desired voice activity detection signal.

An apparatus includes a noise reduction headphone comprising one or more microphones and an acoustic transducer, the one or more microphones configured to generate an input signal; and a controller comprising one or more processing devices, the controller configured to: process the input signal through one or more noise reduction filters to generate a noise-reduction signal, compare the input signal to an estimate of ambient noise to determine if the energy of the input signal is greater than the estimate of ambient noise, wherein if the energy of the input signal is greater than the estimate of ambient noise by a predetermined amount, a change in the noise reduction signal is suppressed; and generate an output signal, the output signal comprising, at least in part, the noise-reduction signal, wherein the acoustic transducer is configured to produce an acoustic output in accordance with the output signal.

Systems and apparatuses are described to automatically balance acoustic channel sensitivity. A computer readable medium containing executable computer program instructions, which when executed by an acoustic signal processing system, cause the acoustic signal processing system to perform a process that includes calculating a long-term power level of a main acoustic signal to obtain an averaged main acoustic signal. Segments of the main acoustic signal are excluded from the averaged main acoustic signal using a desired voice activity detection signal. A long-term power level of a reference acoustic signal is calculated to obtain an averaged reference acoustic signal. Segments of the reference acoustic signal are excluded from the averaged reference acoustic signal using the desired voice activity detection signal. An amplitude correction signal is created using the averaged main acoustic signal and the averaged reference acoustic signal. The amplitude correction signal is used to adjust either the main acoustic signal or the reference acoustic signal to automatically balance acoustic channel sensitivity.

Systems and apparatuses are described to automatically balance acoustic channel sensitivity. A computer readable medium containing executable computer program instructions, which when executed by an acoustic signal processing system, cause the acoustic signal processing system to perform a process that includes calculating a long-term power level of a main acoustic signal to obtain an averaged main acoustic signal. Segments of the main acoustic signal are excluded from the averaged main acoustic signal using a desired voice activity detection signal. A long-term power level of a reference acoustic signal is calculated to obtain, an averaged reference acoustic signal. Segments of the reference acoustic signal are excluded from the averaged reference acoustic signal using the desired voice activity detection signal. An amplitude correction signal is created using the averaged main acoustic signal and the averaged reference acoustic signal. The amplitude correction signal is used to adjust either the main acoustic signal or the reference acoustic signal to automatically balance acoustic channel sensitivity.

A noise reduction system for actively compensating background noise generated by a noise source in a noise reduction area in a passenger transport area of a vehicle. The system includes a microphone array having a reference microphone. An averaging unit is configured to calculate an average error signal, which is calculated based on at least the error signal of a virtual microphone and a direct residual signal of a directed monitor microphone.

An apparatus includes a noise reduction headphone comprising one or more microphones and an acoustic transducer, the one or more microphones configured to generate an input signal; and a controller comprising one or more processing devices, the controller configured to: process the input signal through one or more noise reduction filters to generate a noise-reduction signal, compare the input signal to an estimate of ambient noise to determine if the energy of the input signal is greater than the estimate of ambient noise, wherein if the energy of the input signal is greater than the estimate of ambient noise by a predetermined amount, a change in the noise reduction signal is suppressed; and generate an output signal, the output signal comprising, at least in part, the noise-reduction signal, wherein the acoustic transducer is configured to produce an acoustic output in accordance with the output signal.