What manner of articulation is defined as sound gliding into another phoneme, making it difficult not to add a schwa sound at the end?

The correct answer is glides, which are produced with a relatively open vocal tract, allowing for a smooth transition between sounds. In the case of glides, the articulation begins with one vocalization position and then shifts to another, often resembling vowel sounds. This characteristic of glides, where one sound glides into another, can create a phonetic environment that makes it challenging for speakers to avoid the addition of a schwa sound at the end, particularly when transitioning between vowels.

This merging quality not only influences pronunciation but also the rhythm and flow of speech. In contrast, affricates are produced by briefly stopping the airflow and then releasing it, which does not create the same blending effect as glides. Nasals involve airflow through the nasal cavity, and fricatives are characterized by turbulent airflow through a narrow constriction. Each of these manners of articulation has distinct features that do not contribute to the gliding transition between sounds as glides do.