The mnemonic for the difference between prenasal and postnasal consonants is as follows:
The prenasal consonant ends in n, and the postnasal consonant ends in ng. The difference in pronunciation between prenasal and postnasal consonants can be seen in the following ways:
(1) The tongue position is different. When pronouncing the prenasal -n, the tip of the tongue is pressed against the upper gums, don't loosen it and don't retract it; when pronouncing the postnasal -ng, the back of the tongue is raised high, and the root of the tongue tries its best to retract against the soft palate.
(2) The shape of the mouth is different. When pronouncing -n, the upper and lower incisors are opposite to each other, and the mouth shape is more closed; when pronouncing -ng, the upper and lower incisors are farther apart, and the mouth shape is more open.
(3) The timbre is different. The prenasal -n is sharper and brighter, while the postnasal -ng has a thicker and louder sound.
Techniques for pronouncing prenasal and postnasal consonants
Pronouncing prenasal rhymes should be done with the tip of the tongue toward the upper gums, not with the root of the tongue toward the soft palate.
The final phoneme of the prenasal consonant is a prenasal consonant. When pronouncing the prenasal consonant, the root of the tongue should be lowered naturally, so that the airflow reaches the mouth directly, and then returns to the nasal cavity after being blocked by the tip of the tongue and the upper gums to produce a **** sound. If the root of the tongue is raised and the soft palate is touched together, the final sound is inevitably a post-nasal sound.
Try to pronounce the prenasal sound "an". After pronouncing "a", the tip of the tongue is lifted upward against the upper gums, and the airflow reaches the nasal cavity and ends the pronunciation. It's easy to pronounce "an" in this way.
Summary: The state of the tongue after pronouncing all prenasal rhymes is that the tip of the tongue rests against the upper gums, and the root of the tongue is naturally lowered. Instead, it is rolled backward.