Board Thread:Questions and Answers/@comment-1050617-20140227054202/@comment-53539-20140301225304

Also for those who don't understand the layers of pitch.

Basically, Vocaloid phonetic data is recorded in 3 or more pitches for each note sample. Usually, a high, a medium and a low set of pitching at least. If just one layer is wrong, it can throw the whole vocal off slightly and causing pitching issues when matching notes during the mixing stages. As the vocal goes up and own the octaves, the layers of pitch help adjust the vocal to match going up and down the octaves, however, if the pitch layers are off it sounds less realistic.

Notably, this is a key difference between how a realistic "professional singer" is handled by Vocaloid, as getting the layers right will give it a realistic feeling... And the voice acted vocals like Gachapoid and Miku herself don't really have to worry about sounding realistic, just maintaining their vocal characteristics going up and down the octaves. :-/