[provigil]

high pitch/frequency "noise" that's always there in the background, much too low to be a nuisance.

Interpreting this is a bit difficult to me as well. It is a well known fact that, at least in younger folks, some hearing loss, and an associated mild tinnitus(usually a high frequency sound), is extremely common, due primarily to damage to the hearing mechanism by the noisy environment we live in (music via ear-plugs, cars, sports, publis transportation media, movies, computer games, computers running, on and on). Certainly, our environment is extremely noisy in comparison with, say, 500 years ago or at the dawn of our species). As to a noisy universe, the current understanding of sound requires a medium through which it can be transmitted (a gas or liquid or solid); unless sound travels through dark matter, I doubt that "the universe" is "noisy" - but our world is becoming progessively more so.

I wondered, while reading "The Sound of Silence", if the sound he referred to reflected the neuronal chatter that is constant and characteristic of the brain. I've also noticed, if I close my eyes and note the background of darkness that I "see" (that my visual cortex "sees"), there are variations of darkness that come and go - probably also reflecting constant brain activity/chatter.



I'm not claiming that this is what Ajahn Sumedho is referring to but I wonder.

I was exposed to extreme noise as a youngster. I am aware of a high frequency hiss that is constantly present - and is associated with mild high frequency hearing loss as measured by the standard testing devices. I can focus on and listen to this if I choose.