The nasal cavity plays a role in vocalization. Nasal sound is a part of speech composition, and the strength of nasal sound is directly related to the quality of speech. The consonants m, n and ng of speech must be emitted through the nasal cavity. When pronouncing, the air flow path of the mouth is blocked, the soft palate is drooping, and the sound made by nasal ventilation. A class of consonants classified by pronunciation method. When pronouncing, the airflow passage in the oral cavity is blocked, the soft palate droops, and the airflow passes through the nasal cavity. The general nasal sound can also be regarded as a kind of stop sound, because the airflow path is blocked when pronouncing. Some pronunciation methods will be confused with nasal sounds, such as semi-vowels. When various diseases occur in the nasal cavity or soft palate, the normal nasal sound will change.
Tone change (ancient Chinese: semi-tongue sound) is one of the pronunciation methods. When pronouncing, the middle of the airflow channel in the mouth is blocked, and the airflow passes through both sides of the tongue. The origin of medieval sounds and the L in Mandarin are marginal sounds. Lateral sound, also called lingual side sound and stop sound, is a kind of consonant divided according to the obstruction of airflow when pronouncing. The airflow on one side of the tongue is called unilateral consonant, and the airflow on both sides of the tongue is called bilateral consonant. Consonants produced by the obstruction of the middle passage of the mouth and the passage of air from the lingual side. For example, the L pronounced in Mandarin.