audio signal is sampled by ADC,and reconstructed.
What you heard is the reconstructed signal. The background noise is come from oscilloscope, the background noise of reconstructed signal can not be heard, even with a earphone.
blue trace : output digital steam.
yellow: loop sampler gate.
red: input audio
ADC : 1 bit quantizer; first order modulator; loop sampler frequency 1.6 MHz.
