The lower ranges of the voice in speaking or singing WordNet 3.0 & Open English WordNet

Chest voice is a term used within vocal music. Wikipedia

Voice type Wikidata

A kind of voice of a medium or low pitch and a sonorous quality ascribed to resonance in the chest, or thorax; voice of the thick register. It is produced by vibration of the vocal cords through their entire width and thickness, and with convex surfaces presented to each other. Wiktionary

Voice of thick register. Wiktionary (translation)