An ethnomusicologist is a scientist who studies

An ethnomusicologist is someone who studies music throughout the world

An ethnomusicologist is a scientist who studies music in its cultural and social dimensions.

Explanation:

Ethnomusicology is an academic area linked to anthropology and ethnology, that studies music as a cultural phenomenon. It focuses on people making music in different cultures and societies around the world and what it can tell about the different worldviews, concepts, and psychologies related to those cultures.