Is the (US) black accent changing?

… and if so, why?

In recent years, I’ve noticed that many African-Americans now talk with an accent that resembles the inflections of certain rap artists; it’s a bit tougher-sounding, with an emphasis on the “o” sound.

Where did the rap inflection get its start, anyhow?

I agree. IMO, & a generalization, "Black speech "as best as I can tell once sounded Southern. It certainly, among the younger,now sounds different. The 1st rappers were from NYC-Sugar Hill gang & Run DMC. More recently out of Compton & Long Beach Cal too. The Cal blacks used to have a much "whiter " accent than other blacks. That has changed in the past 15-20 years. This refers of course to the younger ones.

Boy, this thread will attract many posts i think.

Nope, unfortunately. Stuck at two.

It’s not just the accent of black Americans that is changing. I would venture that the speech patterns of ALL Americans changes over time what with easy cross pollenation (ie suburban kids using words that were previously exclusive to inner city urban kids)

All accents of all living languages always change.

The moment they stop changing is the moment they disappear.

They don’t change so much within an individual speaker, but you can hear obvious differences between generations.