Vowels must be relatively easy. And the B at the beginning of the word, I’m assuming is harder than the middle or ending. If your name is Bill, for example, you could say “Imbill” instead of “I’m Bill”. Or easier would be “Imill”. It doesn’t sound exactly like a B sound but we don’t say our sounds perfectly depending on the context of the adjacent sounds. So, for example, in the word “butter” we usually say “budder,” and don’t think twice about the way the “t” is substituted for a “d” sound. They sound very similar and no one thinks twice about it. By saying “I’mill” in stead of I’m Bill ( or Bryan, etc) the listener “fills in the blanks” without being conscious of it. If it is an uncommon name it may not work as well. — former SLP.