I could not recognise the last word of the sentence (PROV), although listening to it numerous times it sounded like a word beginning with B. Now, knowing the correct word I
ve replayed it several more times and Im convinced it still isn
t a P. Lets ope its my audio and not the systems!
I think that rule is old-fashioned. The only phrases where that is even remotely acceptable nowadays are 'an hotel' and 'an historic [occasion, day etc]'. However, most of the time people use 'a' even for these words.
So, in general I would advise always using 'a' with h-words. I'm a UK English speaker.