YOU SAID:

i was watering the plants when i suddenly heard a noise

INTO JAPANESE

植物に水をやっていたとき、突然物音が聞こえました

BACK INTO ENGLISH

When I was watering the plants, I suddenly heard a noise.

INTO JAPANESE

植物に水をやっていると、突然音が聞こえました。

BACK INTO ENGLISH

As I was watering my plants, I suddenly heard a sound.

INTO JAPANESE

植物に水をやっていると、突然音が聞こえました。

BACK INTO ENGLISH

As I was watering my plants, I suddenly heard a sound.