I've found another literary reference to African work chants. In this case its Eritrean day laborers cleaning the bottoms of ships in a dry dock in the Port of Massawa on the Red Sea during World War 2, from Under the Red Sea Sun by Commander Edward Ellsberg, pp. 173.

Commander Ellsberg was in charge of bringing the former Italian Navy yard, which had been sabotaged by the Italians before their defeat by the British and Ethiopian forces, back into full operation. When he got the floating dry dock operational and work had begun scraping the barnacles and weeds off the bottom of the first transport ship, he was greatly disappointed in the pace of the work. He then proposed an economic incentive to the sheiks in charge of the labor force, that if their work crews could do the job in less than the three days contracted they would still be paid three days wages. This was the result:

Then the Eritreans went back to work. Had I waved a magic wand over those Eritreans to transform them, the results could not have been more miraculous...A fierce jungle chant, drowning out all else, rose from all over the dry dock and never ceased; to its barbaric rhythm, there were those puny, previously lifeless Eritreans dancing wildly beneath the hull of the Koritza, while they slashed savagely away overhead with their scrapers at the barnacles!

Of course no attempt was made by Commander Ellsberg to transcribe the work chants but the work was done ahead of schedule, two days instead of three.

It should be mentioned that the climate in Massawa is best known for its high humidity and 100 degree plus F. temperatures.

Charley Noble