frightening

become, get

The noise from the storm became frightening as it got louder throughout the night.

make sth

Loud noises make the situation frightening for young children.

find sth

She found the dark forest path quite frightening when she walked alone at night.

for

Flying in a thunderstorm can be quite frightening for nervous passengers.

to

Giving a speech in front of hundreds of people can be quite frightening to someone who is shy.