Hi I am new to soprano and this is my second time practice. I am using a Antigua 586LQ and original MP. I found that when I play "Do" in middle pitch (press all bottons and octave botton), some funny noise come out. It sounds like "Zzzz". I am not sure where is from but I personally feel that it comes from mouthpiece. It also soundx like air or water leaking somewhere around month. When it comes to "Re" and others, there is no noise. I also tried "do"in low pitch (do not press octave), no such noise. Do anyone know why? Thanks a lot!