Final answer:
The oral cavity proper is the area of the mouth where the tongue moves to create different vowel sounds, and it is essential for the resonance required in human speech.
Step-by-step explanation:
The area of the mouth within which the tongue can move to create different vowel sounds during speech is known as the oral cavity or oral cavity proper. The oral cavity proper is the area of the mouth where the tongue moves to create different vowel sounds, and it is essential for the resonance required in human speech.
Human speech is produced by shaping the cavity formed by the throat and mouth, the vibration of vocal cords, and the movement of the tongue which adjusts the fundamental frequency and overtones. This area is crucial for creating the resonance needed for vowel sounds.
The mouth and throat form an air column closed at one end that resonates in response to the vibrations in the voice box, with the spectrum of overtones and their intensities varying with the mouth shaping and tongue position, thereby forming different vowel sounds.