Obviously if you've been silenced, at least 10 people disagree with your definition of the difference between spamming and ranting.
Actually, we don't know what the 'critical number' is. We've never been told how many people it takes reporting someone for spamming, in what period of time, before the automatic silencing feature kicks in. I've heard numbers as low as 4 people within a minute from people experimenting, but that is at best apocryphal and what we call in the business 'anecdata.' =) We have no hard or soft numbers confirmed either officially or through experimental rigor.