Because babies and dogs don’t speak English (or French, or Spanish, or Swahili, or…)
Intonation is a universal language. There are melodic patterns that have the same effect on infants of any culture, as well as on our very sensitive animal companions. A rising pitch captures attention and engages; a falling pitch is calming; a short, sharp tone interrupts and stops unwanted behavior.
The musical cadence of “baby talk” is comforting and reassuring. It also makes each of us, as the speaker, feel more authentic, caring, and effective as caregivers.
So, when I have a protracted conversation with my sweet Sadie, I invariably slip into that sing-songy, and rather silly, voice. I’ve never even tried to avoid doing so.