i do understand that melisma has existed in many song styles and cultures for centuries. But I still think that the particular style of ad-libbing that is so prevalent in modern pop singing (a very self-indulgent, wavery, wailing) is measurably different from the sort used in, say, classical opera or oratorio.

In classical music, there are clearly defined sections for the soloist, sometimes marked "ad-lib", for a few bars or one extended bar at a climactic point in the music; there are also choral or solo sections where the music is notated in a way that places a single syllable across many notes ("Unto us a child is bo-o-o-o-o-o-o-o-orn", etc). But this latter form is precisely notated, and sung strictly in rhythm and pitch as written, so it can be done by a whole choir or section of a choir, as one. They are not improvised riffs or flourishes, they're just sections of fast-paced music in which a few syllables are stretched across lots of short notes.

The currently fashionable melisma is much closer to the style used in gospel music, adn I think there's a direct link there, as gospel has had a big influence on American pop music.

Marje