I just started fast-noting as my vipassana practice about a week and a half ago and have made fast progress up to what I think is the three characteristics stage (3rd nana?). The bugs are noisy this time of year, and provide a very fast-pulsing set of sounds to focus my attention on, so I've been naturally drawn to them as my primary object when meditating.
However, sound isn't listed as a primary object in the Vishuddimagga, and I haven't seen other people mention it here.
I've made seemingly fast progress through the first two stages, but the A&P seems to be slow to come on. I keep having intense flickery-light/total exhaustion experiences at the end of my sits of fast-noting, but they don't seem accompanied by any new insight in the same way that the first two stages have been, nor do I feel any of the characteristic post-A&P sensations.
So I'm led to a little bit of doubt: Maybe I should pick a more standard primary object? Does anybody else use sound?
