She sounds like a cutie.
Sebrights are full of surprises, so although mine does not "sing" it wouldn't be shocking to hear of one that one does. I've heard of female Sebrights crowing. I even know of one that let out a couple tiny crows after laying an egg - instead of an egg song. (It sounded like a hic-up.)
Mine is very vocal & has an entire vocabulary of little squeeks & squawks depending on the situation. She makes the cutest little chittering when she's angry with another hen or upset that I gave a treat to another while she has none. LOL She also makes a sweet chatter while following me around. It sounds like she's telling me all about her day. Then there's always the long clucking when she's begging for something and a happy trill when she gets it. Her egg song is of course the highest pitched, so I can always tell when Trouble lays an egg. Like I said, she has quite a repertoire of sounds.