“Speech Sounds” is about what happens when humanity loses its capacity for language. In the world that Butler creates, a mysterious illness has severely impaired people’s ability to communicate verbally. The illness also often leads to an inability to read and write, a poor memory, intellectual impairment, and even death. The rapid decline of organized society into postapocalyptic chaos demonstrates humanity’s natural interdependence and social connection. Cut off from the capacity to connect, the people in “Speech Sounds” are sick. The story implies that language is a fundamental and defining characteristic of humanity. Without it, people cease to be people.

With the illness, humanity is no longer empathetic. Instead, jealousy is a prevailing emotion that often escalates to violence and even murder. When Rye learns that Obsidian is literate, “she had never experienced such a powerful urge to kill another person” (Paragraph 50). This urge is not unusual. The likely explanation for the man murdering the woman at the end of the story is his hatred and jealousy over the two children who can speak. It is possible that he was jealous of the woman because she, too, could speak, which would explain why she was silent as she ran from him (rather than wailing unintelligibly).