I've heard from some people that once lived in Spanish-speaking countries that old people in those countries usually speak a "d" sound instead of clearly speaking "t" sound when they get old, and they can't usually distinguish these two sounds.
I find this could be explained using a basic theory. Just consider how this two sounds are pronounced:
- "t" (voiceless dental) should use your tongue to touch the back of the front teeth,
- and "d" (voiced dental) should use your throat to pronounce.
When people get older, their teeth fall out. How can they pronounce the "t" sound clearly and accurately?
So I want to ask whether this is true.