Please help me with a gender question. I think I have a Rooster?!

[hanmarie8]

I have been trying to record the chickens sound but am unable to get a recording because it stops ever time it sees me. It is a 10 weeks old chicken... white with brown spots, unknown breed. Larger then the other chickens bought at the same time, those chickens are 1 black plymoth rock and 2 gold sex links. Anyways, Our unknown chicken makes this almost baa-ing sound. Not a definate cock-a-doodle doo but a baaaaaaaaa or raaaaaaa sound. I know this is not much help but I live in town and am not supposed to have a rooster and am starting to get paranoid that "it" is a he and not a she. It just started doing this maybe a week ago and it's not trying to mount the other chickens... so I'm not sure what to think. PLEASE HELP WITH ANY ADVICE!
Thanks!

 

[K Spot]

Pics would help

 

[aolexa21]

Yes pictures please