I know that every word pronunciation should be studied by itself since English is full of exceptions but I also know there are general rules that apply.
The question is simple: I would like to know what's the rule about the pronunciation of the letter "e" at the beginning of words. Sometimes it is ɪ and sometimes it is ɛ .
For example: "Error" is pronounced "ˈerəʳ" and "erroneous" ɪˈrəʊnɪəs
Thank you in advance!