Correct pronunciation for 北, 白 in Cantonese? 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'?

PS: I want to know for 白 as well, is it paak? (as in 白泥- a place in Hong Kong) or 'baak' as in 白色(baak sik - white color)?

Can b and p be used interchangeably or is there an official pronunciation?
北 is definitely bak1. 

白 is baak6. 

I believe this b/p issue is probably just a romanization problem. Remember 北京 was Peking in times past. 

Words that start with b are usually represented by letter [p] in IPA and that is how many romanizations started, from IPA.

The Meyer–Wempe Cantonese romanization system is one such pinyin that does write the IPA initial [p] as p and not b.