Musicology, the academic study of the subject of music, is studied in universities and music conservatories. The earliest definitions from the 19th century defined three sub-disciplines of musicology: systematic musicology, historical musicology, and comparative musicology or ethnomusicology. In 2010-era scholarship, one is more likely to encounter a division of the discipline into music theory, music history, and ethnomusicology. Research in musicology has often been enriched by cross-disciplinary work, for example in the field of psychoacoustics. The study of music of non-Western cultures, and the cultural study of music, is called ethnomusicology. Students can pursue the undergraduate study of musicology, ethnomusicology, music history, and music theory through several different types of degrees, including bachelor's degrees, master's degrees and PhD degrees.