For speeling purposes have you tried ASMR content?
For example Let’s Find Out makes ASMR content focused on anstronomy and physics stuff and mainly whispering things. Example: youtu.be/U6M7_Pt0d14?si=0By2q3YJ-r95K0TD.
You also have The French Whisperer ASMR, who does a bit of everything (history, some science, reading stories…)
For pure ASMR (but non informative nor anything) RaffyTaffyASMR puts out some solid content.