Talk:KAITO/@comment-75.128.120.148-20120606191257/@comment-5165836-20120606192125

I think they're special recordings that make the flow of the pronouced combination of letters more smooth and realistic. According to the Vocaloid3 article on the wiki:

A new feature in Vocaloid 3 is Triphons, these will instantiate a different sound if a particular set of three phonemes are pieced together, for example, allowing “ka” to sound different in “aka” compared to “ika” improving language quality.