I must say that there have been some excellent contributions to this thread (thankyou) and it is apparent that most if not all replies have been placed by traders who actually make a living out of the markets.
It is certainly not a coincidence that consistent profitability is intrinsically linked with psychological composure. I recall when I read Douglas's Trading in the zone, (about 3 years ago) my initial reaction was one of being repulsed, because at that point in time I recall feeling somewhat persecuted by consistent failure, which was due to the combination of my irrational emotional response to random undisciplined speculations for which I hadn't admitted to myself that I just didn't have a plan. I'm pleased to say that I now have my plan defined and with it the byproduct that is psychological composure.
One trader said to me a few years ago that all you need is psychological composure, retrospectively I disagree, first comes the plan, then the composure which is a byproduct of success, and this success gradually becomes reinforced until a new definition of yourself is created.
Do the voices ever "go away" completely ? I would speculate that after a minimum of one year of consistent profits where the trader uses the 1 min timeframe that it is possible for them to be completely eliminated (In terms of their capacity to influence your actions), as any pause for thought would reduce trading the 1 minute timeframe to a pointless activity (Unless you like losing money, which is a rather dubious thought). However my current thought at this point in my personal journey is that there may always be some kind of emotional chatter (however quiet), because the truth is our system is defined by the probability of an outcome being true, and therefore logically every trade is potentially a losing trade, and this fact must be accepted. Therefore in my humble opinion the acceptance of this fact will always retain a miniscule level of subconsciousness noise, albeit more or less irrelevant noise once the plan is defined.