Speech Sounds and Information

If the disease described in Octavia Butler’s “Speech Sounds” were to actually infect the world, what would happen to the African “talking drums” described in chapter 1 of James Gleick’s The Information? Who would be able to use them and/or understand them—those with the ability to speak or those with the ability to write? To put the question another way, while they’re called “talking drums,” is this communications technology a form of speech, or a form of writing? Why do you think so?