The spelling of the word "bettini" follows the standard rules of Italian phonetics. The initial "b" is pronounced as [b], the "e" is pronounced as [ɛ], the first "t" is pronounced as [t], the second "t" is pronounced as [t͡s], the "i" is pronounced as [i], and the final "ni" is pronounced as [ni]. Therefore, the IPA phonetic transcription of "bettini" is [bɛtˈtiːni]. It is important to understand the rules of phonetics when spelling Italian words to correctly pronounce them.