Pinyin Lessons Study Material GoodChinese
An unaspirated voiceless alveolar plosive. It is pronounced by raising the tongne tip against the upper teethridge to block the air and then putting it down to release the air. The vocal cords do not vibrate .
An aspirated voiceless alveolar plosive. It is pronounced in position for "d", but explodes with a strong puff of air. It is an aspirated equivalent of "d".
A voiced alveolar nasal. It is produced by raising the tongue tip against the upper teethridge and dropping the soft palate to allow the air to run out through the nose. The vocal cords vibrate. 
A voiced alveolar lateral. It is pronounced with the tongue tip a little behind the position for "n" to allow the air to run out from bothsides of the blade. The vocal cords vibrate.