You could hear the grass grow(ing) expression
It is so quiet that you would be able to hear even the tiniest sounds.
The evenings here are so peaceful and quiet that you could hear the grass growing.
Very quiet
Extremely quiet.
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.
"I can hear the grass grow" is the second single by the Move, written by Roy Wood. The song was first released on 31 March 1967. The basis of "I can hear the grass grow" came from photographer Robert Davidson, who had received a letter from an unknown individual that read "I listen to pop music on the radio because where I live it's so bloody quiet that I can hear the grass grow." He promptly told this to Wood, who was inspired enough to write a song regarding the subject.