These sounds are really close together to begin with, but in English, we don't actually use either of those sounds in word-initial position like the example recording, and so unless you speak a language that distinguishes these sounds in this context, they are going to be difficult to differentiate. Our word-initial voiceless stops (p, t, k) are actually aspirated stops, that is they are produced with a strong puff of air, while our word-initial voiced stops (b, d, g) are partially unvoiced and are actually somewhere between the t and d recordings.
Hold your hand in front of your mouth and feel the difference in pressure when you pronounce the first sound of the word "tune" versus the word "dune". This will let you feel that puff of "aspiration." Next, try putting your fingers over the front of your throat, (on your layrnx or where the Adam's apple is on men), and pronounce the sounds slowly. You may be able to feel the difference when your vocal cords start to vibrate as you say the "d" sound. In native English speakers this happens shortly after the pressure is released from your tongue, while in the English "t" sound, the vibration doesn't start until the vowel does. The "d" sound in the example from the chart has the vocal cord vibrations start immediately as the pressure is being released.
> Hold your hand in front of your mouth and feel the difference in pressure when you pronounce the first sound of the word "tune" versus the word "dune". This will let you feel that puff of "aspiration."
The aspiration will be even more obvious if you try speaking into a microphone.
Hold your hand in front of your mouth and feel the difference in pressure when you pronounce the first sound of the word "tune" versus the word "dune". This will let you feel that puff of "aspiration." Next, try putting your fingers over the front of your throat, (on your layrnx or where the Adam's apple is on men), and pronounce the sounds slowly. You may be able to feel the difference when your vocal cords start to vibrate as you say the "d" sound. In native English speakers this happens shortly after the pressure is released from your tongue, while in the English "t" sound, the vibration doesn't start until the vowel does. The "d" sound in the example from the chart has the vocal cord vibrations start immediately as the pressure is being released.