The audience was so quiet you could have heard a pin drop.

观众安静得连针落地的声音也听得见。

《牛津词典》

One could have heard a pin drop.

一根针掉在地上都能听见。

youdao

The room was so still that you could have heard a pin drop.

那房间静得针掉在地上都能听到。

《新英汉大辞典》

If you get out of the range of the GPS tracking system, it will help locate your item on a map with its unique last-seen map pin-drop feature.

FORBES: Uh Oh: I Lost My iPhone 5. Now What?

Proximo delivers a unique way to track multiple valuables with a last-seen map pin-drop feature, an active proximity dashboard and extended battery life on both its Fob and Tag.

ENGADGET: Kensington wants you to be very afraid of losing your iPhone, buy its $60 Proximo system

It might take a while before our on-the-go conversations are pin-drop clear, though.

CNN: Coming to your phone: High-definition voice