Falling silences

Just as I was about to say something witty in return, a hush swept over the crowd.
No, that’s not right, a hush didn’t sweep over the crowd, it fell over the crowd. You may think that there isn’t any difference between the two, but trust me, there is.
A sweeping silence is mundane. You hear them all the time, when someone important enters a room, when someone is making a scene, when musicians begin playing a song. The people closest to the source stop speaking first, their attention caught. Next, their neighbours notice their silence, and they too fall silent when they notice the source. This continues outwards in a wave, until the entire room is doused in the quiet. Like any wave though, sweeping silences aren’t even. They falter and crash as people push back at them, self-important nobles with ego enough for three men, rich ladies who’ve had a few too many glasses of wine, musicians paid to keep playing uninterrupted for the entire night. Sometimes the wave crashes entirely, and conversation merely dims for a few second before people decide their stories are in fact more important than whatever is happening. Sometimes, very rarely, when the person is important enough, or the scene loud enough, or the music beautiful enough, a silence will sweep over a crowd so quickly as to be mistaken for a falling silence. But it is not.
Falling silences are exceedingly rare, as the only occur when the source is so significant, so unequivocally more important than anything else that could possibly be happening in the room at the time. More important than egotistical nobles or drunk ladies or professional musicians, more than the king and his court, or the magically gifted witches. They are the result of extreme wonder, or extreme awe… or extreme dread.
And the hush that blanked the room at that moment fell. And it fell hard.