Depending on the particular language being discussed, it can take the form of a triangle or a quadrilateral. Vowels differ only in the position of the tongue when voiced. The tongue moves vertically and horizontally within the oral cavity. In the vowel diagram, convenient reference quadrilateral properties chart pdf are provided for specifying tongue position.
The position of the highest point of the arch of the tongue is considered to be the point of articulation of the vowel. The horizontal dimension of the vowel diagram includes tongue advancement and identifies how far forward the tongue is located in the oral cavity during production. Vowels are also categorized by the tenseness or laxness of the tongue. Here, the vocal tract is in its neutral state and creates a near perfect tube. In other words, all vowels but schwas. The next dimension for vowels is rounding. Rounding is important because it continues to help differentiate the vowels of English.
For example, when you say , your lips are rounded but when you say , your lips are spread. We can categorize vowels as rounded or unrounded. The standard IPA vowel trapezium. The vowel systems of most languages can be represented by vowel diagrams. For most languages, the vowel system is triangular. Different vowels vary in pitch. Vowels are distinct from each other based on their acoustic form, or spectral properties.
Spectral properties consist of the speech sound’s fundamental frequency and its formants. Each vowel in the vowel diagram has a unique first and second formant, or F1 and F2. The frequency of the first formant refers to the width of the pharyngeal cavity and the position of the tongue on a vertical axis, ranging from open to close. The frequency of the second formant refers to the length of the oral cavity and the position of the tongue on a horizontal axis. F1 frequency because of the narrow size of the pharynx and the low position of the tongue.