I found this to be a very well-written article about a concept I wasn't previously aware of. Here follow some interesting choice quotes - but I recommend reading the actual article:

When activist Jess Piper heard Alabama Republican senator Katie Britt deliver the GOP response to the State of the Union, she had a visceral reaction. The senator spoke in a breathy voice with a soft and sweet quality ― even as she described horrific acts of sexual violence and murder and painted a dystopian picture of the United States.

For Piper, there was no mistaking that sound, which permeated her childhood in the Bible Belt. Britt was using “fundie baby voice.”

Then more context - conveying submission to male authority:

“I would describe ‘fundie baby voice’ as a woman’s voice that is higher than average in both pitch and breathiness,” said Kathryn Cunningham, a vocologist and assistant professor of theatre and head of acting at the University of Tennessee, Knoxville. “While the average woman’s voice is higher-pitched than the average man’s due to a combination of anatomical and social factors, some women who speak this way seem to be intentionally placing their voices higher than their natural pitch range in order to convey submission to male authority and childlike innocence.”

These changes in voice are deliberate:

Deliberate voice changes are very much a reality for women in fundamentalist Christian communities, noted Tia Levings, author of the upcoming memoir “A Well-Trained Wife: My Escape from Christian Patriarchy.”

“From a young age, we were taught over and over again to modulate our voices,” she said. “It was all about sounding sweet, soft, and childlike. There were very strict gender roles, and women were supposed to never sound angry but keep sweet, obey, dress modestly, speak softly, be very feminine.”

Interesting roots:

This sort of Christian vocal training has roots in Helen Andelin’s 1963 book “Fascinating Womanhood.”

“This book encourages fundamentalist Christian women to sound ‘childlike’ in order to convey submission to male figures,” Cunningham said, noting that there are “references to an idealized voice that a compliant, Christian woman should have.”

I found this quote referenced in the article very remarkable:

“It is important to emphasize in this discussion that women’s voices are always scrutinized and policed. The truth is that we can’t win, no matter how we speak.” - Kathryn Cunningham, vocologist and assistant professor

Of such women in power who use the fundie baby voice, the article goes on to quote the following:

“What they produce is a lot of abuse and subjugation,” Levings added. “And it always stings more when a woman is used as a tool of the patriarchy to promote it. They’re the Aunt Lydias and Serena Joys of the program ― brought in and given power when it suits men, but they will be discarded when it’s no longer useful to those men.”

Toward the end of the article, the very valid warning:

Piper urged those who are interested in the fundie baby voice phenomenon to educate themselves on the Christian nationalist movement in U.S. politics and the Project 2025 agenda. Directing ire toward those in power is more useful than tearing down everyday women for the way they were trained to speak.