The idea of keeping silence, or practicing “Noble Silence”, is to extend the quietening of our mind’s chatter to our verbal chatter.
Starting on the evening of the second day of retreat (11th of the month) we keep complete silence until the evening of the 8th day (18th of the month). This means absolutely no talking or extended gesturing to anyone for any reason. Exceptions are for asking questions of the teacher, and at scheduled Interviews. (And of course, in the case of some emergency.)
By keeping silence even when we are sharing the meditation retreat with others, including interactions required for chores, sharing meditation space, and so on, we find out how much of our speech is really necessary – or unnecessary!. And how much we can communicate and learn about each other without it. We do not have to be all grim about it — we can still acknowledge the presence of others with a smile or a bow.