Whats a cheap and unobtrusive way to estimate the BSimple version of the noise scale in real time? Piggy back on ADAM's moving mean and variance estimates? Edit

Whats a cheap and unobtrusive way to estimate the BSimple version of the noise scale in real time? Piggy back on ADAM's moving mean and variance estimates? Edit: I see that Appendix A has a method for the multi-device training setting, but I'm thinking of single device training.