What is a glottal stop?

A glottal stop is indeed characterized by the obstruction of airflow at the level of the vocal cords. It is produced when the vocal cords come together completely, stopping the airflow temporarily before releasing it. This type of consonantal sound is marked in phonetics by the symbol [ʔ]. It occurs in various languages and dialects, serving as a crucial sound that can differentiate meaning.

The other choices do not accurately define the glottal stop. For example, the description of open vocal cords refers to sounds that are voiced, which is the opposite of what occurs during a glottal stop where the airflow is interrupted. The statement about whispered speech does not pertain specifically to the definition of a glottal stop but rather describes a mode of speech that modifies sound production, often without using the vocal cords in a way that characterizes the glottal stop. Lastly, while non-native speakers may sometimes struggle with producing certain sounds, labeling the glottal stop strictly as a feature of non-native speakers overlooks its presence in many language systems, including those of native speakers in various dialects.