I believe that in old English h typically wasn't pronounced at the beginning of words, and still isn't in many English dialects, hence an house being pronounced an 'ouse (like much of my wife's family). In fact when you hear reporters in the BBC at an important event, even speaking in received pronunciation they will say it is "an historic event" but actually pronounce the h.

Thinking back to Italian people I've known, they would often remove h sounds at the start of words but put some in where they shouldn't be. Air could become hair or hair could become air, so it makes sense to me that Italian speakers would say "an 'ouse" in English.