Field hollers weren't endemic to African Americans; they were used frequently by rural whites as well.
To explain for anyone who doesn't know, hollering was a way of long distance communication before technologies for communication existed or were prevalent
Depending on the length, duration, and timing of the whoops a variety of different ideas could be communicated over a long distance since the hollering carried better than regular shouts.
For years there was a hollerin' contest in Spiveys Corner, NC where the hollerers preserved their art and practice, but I believe it may have been discontinued recently. If you're simply looking for recordings, I'm sure a number of modern recordings exist from that event; the gist of the practice is substantially the same.
Later, when I'm at a computer I can look for older recordings and see if any exist.
It may also be of interest to mention the practice of Confederate Soldiers, who would holler and yip in the battle field to intimidate the Northern army and also to motivate themselves. Based on a few recordings made from CSA vets in the early 1900s, some sound editors have recreated what an entire army would have sounded like, and let me tell you, it's intimidating.