Almost impossible to answer "why does someone speak in this way" unless you know something about them.
He may come from a dialectical group, he may be speaking in a foreign language, he may have a hearing disability, he may be using a fashionable accent.
Who is the person and where does he come from?
I'm not at all familiar with the way by which Buddaheart explains pronunciation but I do know that in the UK the long O sound is altered to OR by people from the north (Yorkshire, Lancashire) or Scotland, or even Wales:
Horm (for home), Snor (for Snow) and so on.
In some dialects, home can become almost hum, or snow snahr.
(Buddaheart, is there some established practice that describes phonetics and where could I find reference to it?)