When Tracey returned to Africa in 1969, he quickly got back to his research on African music, carrying on as an associate at ILAM under his father. His field research centred on Zimbabwe, Mozambique, Malawi, Zambia, Uganda, South Africa, and Namibia, focused on the playing technique of members of the mbira and xylophone families. A highlight of Tracey's research was the identification of the lower course of tines on the karimba (i.e., Jege Tapera's mbira nyunga nyunga) as the logical ancestor of essentially all mbiras. Those eight notes can be traced through every mbira and karimba played in the Zambezi Valley, and those eight notes form the core of all kalimba music in that region, which is considered to be the birthplace of the metal-tined kalimba about 1300 years ago. Tracey asserts that the first written account of the kalimba by Portuguese missionary Father Dos Santos, in Mozambique in 1589, was in essence these eight notes. Other instruments, such as the mbira, or the modern karimba (mbira nyunga nyunga), are based on those eight notes, with other notes and other courses of notes having been added over the centuries. While it is impossible to say when those eight notes first started appearing in kalimbas, Tracey's work convinces that the note layout of the karimba is truly ancient and gave rise to all other kalimbas in the region.