1-bit recording is in fact a common thing for very noisy signals. You're actually aggressively over-sampling and using correlations over many samples (in time) to get the signal out from under the noise. I've only glanced over it, but this looks like a fun related article, but driving the opposite way (oversampling to get more effective bits) https://thecavepearlproject.org/2017/02/27/enhancing-arduino...