Actually, Mudit, Th in English has no equivalent sound in hindi. The sound th is an unvoiced (no vocal cords used) consonant made by placing your tongue just under your incisors and blowing air through them. We Indians approximate it to "th" (for a lack of an indic script to represent it), a dental consonant, the first one in fourth row in the consonant table of the devanagiri script, like in Thakan. The english T is a voiced plosive aveolar consonant, made by placing the tongue just above the point where the incicors meet the gums and blowing air out. (in the devanagiri script, the second and 4th consonants are plosive. Place your hand in front of your mouth and notice the difference in the air-speed and volume when you say them). Indians approximate T to the first consonant in the third row of the consonant table - like the T in tapori.
Neither is correct. Unfortunately, we have more T sounds than the roman script accomodates. Most other languages use accents to get additional sounds - like french, spanish, portuguese etc.
