So quiet you could hear a pin drop phrase informal idiomatic
Extremely quiet.
The children went out and the room was so quiet you could hear a pin drop.
After he announced that he would resign, the meeting room was so quiet you could hear a pin drop.
The crowd fell so quiet you could hear a pin drop as the horrible news was read aloud.
Very quiet
It is so quiet that you would be able to hear even the tiniest sounds.
Used when one suddenly becomes quiet because one is nervous, upset, or does not want to mention a particular topic.
Do something silently, secretly.
1. To keep silent.
2. To prevent someone from divulging information.