Which of the following is true regarding vowels?

Vowels are always produced with an open vocal tract, allowing air to flow freely without significant constriction or blockage. This is what makes them distinct from consonants, which often involve some form of obstruction in the vocal tract. In terms of voicing, vowels are characterized by the vibration of the vocal cords during their production, making them voiced sounds.

While consonants can be either voiced or voiceless, vowels do not have this distinction; they are inherently voiced. This aspect is fundamental in the categorization of speech sounds in phonetics. Understanding that vowels lack a blockage point further reinforces the idea that they are produced differently than consonants, which typically have a defined place of articulation that creates a degree of constriction. Thus, the statement that vowels are always voiced sounds accurately reflects their phonetic nature.