While I have a background in music (as fine arts), I am less familiar with pop and its associated analysis, which tends to be culturally-based. There is a diction in singing that seems to have shifted vastly over the past 60-70 years. There is a style of singing and annunciation in the earlier period I pick up on from, say, The Andrew Sisters or Doris Day or other popular artists from the late 40s to early 60s. The diction and style seems to expand in the late 60s to include folk styles. Nonetheless, that popular music singing diction has much in common with the earlier period. This seems to remain true into the 1980s. For example, Rita Coolidge or Laura Branigan are not terribly far off from earlier singing styles.
Now, in 2019, I don’t recognize the pop singing styles or where they’ve evolved from. There seems to be no connection to the earlier period. What transpired?
Here is an example of what I consider a modern style of diction in singing: https://youtu.be/6v-7PVtdvVk (I chose this example from a pop singer named Ariana Grande, as it seems to have relatively less audio processing versus modern studio recordings.)
Here is Laura Branigan, simply for sake of example, circa 1983: https://www.youtube.com/watch?v=HInA9jKyoKE (a style of diction in singing not unlike earlier pop vocalists; apparently no longer in existence; I could have used Karen Carpenter here as an example, as well)
Here is Doris Day in 1954: https://www.youtube.com/watch?v=UG3FofPUrt8 (again not terribly different to our example of Laura Branigan; older folks might call this "proper singing" or proper diction)
Something seems to have shifted in the 1990s or early 2000s. The older style of pop vocal diction has disappeared. I am using female singers for my examples here to simplify any potential analysis, but I think male vocals have similarly changed. Pop female vocalists now sing in this unnamed style very similar to Ariana Grande. What is this style called, and what are its origins?