My youngest daughter aged 2, has and always has had a very deep and unusual voice. We just thought it was a quirk about her that we loved. However as she became more vocal, more and more people commented on it and asked us if she was sick or had a sore throat. After a while, these comments got me thinking and I took her to the doctor, really for her to say I was being silly and nothing to worry about. But she didn't, she took the safe road and said that it wouldn't hurt for a specialist to look at her.
That is where we went today. The specialist said that yes, she has a very deep and unusual voice but that there were no other problems to suggest that there was a problem. If I wished, I could have her vocal cords looked at to be 100% sure but that would mean she had a general anesthetic. No thank you - not unless I really need to.
She did suggest we see a speech therapist, just to monitor her voice and get her opinion over a period of time. So - all happy, she is just quirky.