The audio here is generated speech. A recorded human voice for this lesson is on the way.
The two sounds
For D and T, the tongue tip touches the ridge just behind your top teeth, then lets go. Same place, same movement. The difference is the voice: D buzzes, T is silent with a small burst of air. Touch your throat and say "duh", then "tuh". The buzz is on D only.
American English adds one twist that surprises learners. Between two vowels, T often turns into a quick, soft D-like tap: "water" sounds like "wadder", "city" like "siddy", "better" like "bedder". That is not a mistake, it is how Americans speak. You don't have to copy it, but you must recognize it, or common words will sound unfamiliar.
Hear the difference
Tap each word. Then test your ear.
At the end of a word, the vowel before D is longer: "ride" stretches, "right" is clipped.
Say it out loud
Tap a sentence to hear it. Say it after the voice.
Listen for the American tap in "water" and "bottle".
Practice · 3 min
Repeat each sentence after the model. First say every T with a clear puff. Then say the last sentence the American way, tapping the T in "water" and "bottle", and hear the difference.
Say it today
Use it once in a real conversation before tomorrow. Out loud counts, even to yourself.