Referring to Cantonese Sheik, 北 is normally pronounced as 'bak', as in 北角 (bak gok - a train station in Hong Kong). However, I have seen instances where it is pronounced as 'pak' as in 北潭涌 (Pak Tam Chung- a place in Hong Kong).
So, is 北 officially pronounced as 'bak'? or as 'pak'?
Can b and p be used interchangeably or is there an official pronunciation?