What is "oooh"

Usage examples of "oooh".

People were herding together, watching the event, ooohing and aaahing.

His name tag said VALENTINE, and I ate up his attention with a spoon as he helped me choose a good pair of boots, ooohing over my silk stockings and caressing my feet with his strong, cool fingers.

His stepmother ooohed and aahhhed at a sleek alabaster yacht that swept by, out beyond the bay’s protecting spit of sand.