Collocations for startled - adj.

appear, be, look, seem, sound

extremely, fairly, very, etc.
a little, slightly, etc.
for a moment, momentarily
She was momentarily startled by the sight before her.

suddenly
clearly, obviously

at
She was obviously a little startled at this idea.

by
I was startled by his sudden appearance in the doorway.

Startled is used with these nouns:
cry, gasp, horse, look, yelp