Thoracic resonance is the whole resonance caused by vocal cord vibration, which causes the air column vibration in trachea, and then affects the whole chest cavity, including the whole brain area from diaphragm to the top of trachea.
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The so-called chest resonance is a method of practicing vocal music, and it is also a vocal term, which follows the saying that 19 century science is underdeveloped. Chest resonance's feeling is obtained by half yawning his throat. When making sound, the mandible naturally droops, the larynx and pharynx are properly opened, and the reflection point of sound wave vibration on the hard palate is moved to the back of the lower teeth.
Make the sound wave cause greater vibration near the larynx and trachea, and then transmit it to the chest to produce resonance. At this time, it seems like singing the voice to the chest. When singing bass, the chest cavity is the main resonance organ, followed by the oral cavity and pharyngeal cavity, followed by the head cavity.
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