Which type of speech sound involves partial obstruction of airflow?

The type of speech sound that involves partial obstruction of airflow is indeed a consonant. Consonants are produced when airflow is obstructed at some point in the vocal tract, which can occur at various locations and with varying degrees of constriction. This partial blockage creates different sounds depending on how the airflow is modified, such as through the positioning of the tongue, lips, or teeth.

In contrast, vowel sounds are produced without any significant obstruction of airflow, allowing the air to flow freely. Diphthongs, which are complex vowel sounds that begin with one vowel sound and glide into another, also do not involve obstruction but rather a smooth transition between two vocalic elements. Glides, similar to diphthongs, are characterized by a smooth movement of the tongue and do not involve significant airflow blockage either.