That would actually be easier! If you also want UPPER CASE vowels you would need to add the upper case codes 65 ,69,73,79,85
Code:
Sub findLCVowels()
Dim osld As Slide
Dim oshp As Shape
Dim L As Long
For Each osld In ActivePresentation.Slides
For Each oshp In osld.Shapes
If oshp.HasTextFrame Then
If oshp.TextFrame.HasText Then
For L = 1 To oshp.TextFrame.TextRange.Length
Select Case Asc(oshp.TextFrame.TextRange.Characters(L))
'97,101,105,111,117 are vowels
Case Is = 97, 101, 105, 111, 117 ' lower case vowels
oshp.TextFrame.TextRange.Characters(L).Font.Color.RGB = RGB(0, 0, 0)
Case Else
'do nothing
End Select
Next L
End If
End If
Next oshp
Next osld
End Sub
Note there was an error in the first code 65 should be 97