He is an expert in osteology and has a deep knowledge of the human skeleton.

He is a world-renowned osteologist.

He is an expert in osteology.

In Sanskrit phonology, retroflex sounds play an important role.

A back vowel is a sound where the back of the tongue approaches the palate.

Back vowels are vowels that are pronounced using the back of the tongue.

A coronal is a sound that is pronounced using the tip or the upper part of the tongue.

Retroflex sounds are difficult to pronounce.

Retroflex is a phonetic feature that does not exist in Japanese.

A dorsal sound is a sound that is pronounced by the back of the tongue approaching or touching the palate or pharynx.