Patent ID: 9071214
Filing Date: 2015-06-30
Classification: H03F,H03G,H04R,H04S

Abstract:
1. A microphone device comprising a microphone transducer element, adapted to execute the steps of: receiving an audio input signal from the microphone transducer element; attenuating the audio input signal from the microphone transducer element; generating a first and second digital audio signal from the audio input signal; estimating a signal feature of the first digital audio signal or the second digital audio signal, monitoring the first and second digital audio signals and detecting respective zero-crossings of the first and the second digital audio signal, detecting a simultaneous zero-crossing of the first and second digital audio signals, comparing the estimated signal feature with a predetermined feature criterion, wherein the predetermined feature criterion comprises a level of the first digital audio signal or a level of the second digital audio signal or a combination of levels of the first and second digital audio signals, switching from transmitting the first digital audio signal to transmitting the second digital audio signal to a controller output, or vice versa, only at the simultaneous zero-crossing of the first and second digital audio signals based on the comparison between the estimated signal feature and the predetermined feature criterion by: initializing a peak tracking variable, MaxPeak, representing a maximum absolute value of the first or the second digital audio signal between a pair of consecutive zero-crossings of the first or second digital audio signal, to an initial value; comparing an absolute value of a current audio signal sample, ABS x(n), of the first digital audio signal or the second digital audio signal with a current level estimate, Yp(n−1); computing an updated level estimate, Yp(n), with a first time constant if the absolute value of the current audio signal sample is larger than the current level estimate, Yp(n−1), or computing the updated level estimate, Yp(n), with a second time constant if the absolute value of the current audio signal sample is smaller than the current level estimate, Yp(n−1); comparing the value of peak tracking variable, MaxPeak, with the updated level estimate, Yp(n); wherein if the updated level estimate, Yp(n), is larger than the peak tracking variable, MaxPeak, updating the value of MaxPeak to Yp(n), and if the updated level estimate, Yp(n), is smaller than the peak tracking variable, MaxPeak, retaining a current value of MaxPeak; detecting a zero-crossing of the first digital audio signal and the second digital audio signal, and comparing the value of MaxPeak to a first predetermined threshold level when a zero-crossing is detected; wherein if the value of MaxPeak is larger than the first predetermined threshold level: switching from transmitting the first digital audio signal to transmitting the second digital audio signal to the controller output or continuing transmission of the second digital audio signal to the controller output; and if the value of MaxPeak is smaller than the first predetermined threshold level: switching from transmitting the second digital audio signal to transmitting the first digital audio signal to the controller output or continuing transmission of the first digital audio signal to the controller output.