**VBA (Excel), with an *amazing* 322 bytes**


Yeah, and I *LOVE* hexadecimal. (There's no sarcasm font yet, so I'm using italics for now) I'll add comments if someone wants, but I think it's self explanatory.

    Sub b(s)
    For Each c In Split(Replace(s,"D",""),"B")
    Select Case c
    Case"I"
    c=0
    Case"A"
    c=1
    Case"O"
    c=2
    Case"U"
    c=3
    Case"II"
    c=4
    Case"IA"
    c=5
    Case"IO"
    c=6
    Case"IU"
    c=7
    Case"AI"
    c=8
    Case"AA"
    c=9
    Case"AO"
    c="a"
    Case"AU"
    c="b"
    Case"OI"
    c="c"
    Case"OA"
    c="d"
    Case"OO"
    c="e"
    Case"OU"
    c="f"
    End Select
    d=d &c
    If Len(d)=2Then
    E=E &Chr("&h"&d)
    d=""
    EndIf
    Next
    Debug.?E
    End Sub