They look female alright. Do you have any roosters? If not, then one of the hens could be taking the role of a rooster. It's usually normal. It happened to me once. Sometimes they will attempt to crow but it will sound off. They will also attempt to mount the other females but just in display of dominance. They will also most likely stop laying eggs. One of the hens could eventually change sex.
Hens get noisy as they get ready to start laying eggs, practicing their ' egg song' which can kind of sound like crowing sometimes. You have one that looks like she'll start laying any day now. I had a pullet who crowed before she started laying eggs but once she'd started she stopped with the crowing (thankfully).
Those are hens - like EmbertheChicken said, one will sometimes decide to crow and act like a rooster. They don't actually change into males, but they start to display secondary sex characteristics like crowing, feathering like a male, dominant behaviour and no more eggs. I've read that illness or an injury to their ovaries sometimes can cause it. It happened to one of my Rhode Island Reds "Rooster", who had recovered from an earlier unidentified illness (vomiting water, sitting in the corner and not moving), but after we got a real rooster, "Rooster" starting laying again and behaving like a hen.