How has popular music singing evolved over the past 70 years to where it is now?

Question

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?

ADDENDUM:

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?

Answer 1

The modern pop vocal style has its distant origins in the black American gospel music of the 50s and 60s. Compare this early recording of Aretha Franklin from the 1950s for an example. It's a more emotional and raw sound, with a more bluesy, African-American diction, and an abundant use of improvisational melisma, the singing of multiple notes on a single syllable.

The immediate adoption of gospel vocal styles into popular music was a secularization of gospel called "soul music", which was brought into mainstream popularity in the 60s and 70s by figures such as Franklin, Ray Charles and Sam Cooke. The soul-influenced vocal colonized mainstream pop via superstar Mariah Carey's reign on the pop charts in the 90s. Later, after the rise of Christina Aguilara in the 2000s, this style of singing became the universal standard. The modern version is essentially the same, with the addition of more processing and auto-tune.

So, in summary, a lot of what you're hearing over the course of pop music vocal history is the increasing mainstream dominance of black American diction. Interestingly, there's been a bit of a reverse progression in rock music. Most of what we think of as the "classic rock" vocal sound is white American or British imitations of black American blues musicians, whereas more recent indie and alternative rockers often have less of a directly black-influenced sound.