Hello,
What you must be observing is the vagina and it can be due to vaginal wall, polyp, a wart or even any septum. What exactly it is can be diagnosed only after a physical examination and a pelvic examination by a gynecologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.
You really should see your Dr about this. Don't worry because Drs see and hear everything you can imagine. I'm not sure what it could be. I wish I could be of more help but all I can say is you really should get this checked out by your Dr.