Ikemefuna's nervousness in the face of hushed whispers and mumblings could stem from several reasons, depending on the context within Chinua Achebe's "Things Fall Apart":
Cultural Significance of Secrecy and Gossip: In Igbo culture, whispers and secrets often carry weight. They might hint at impending danger, hidden agendas, or taboo topics. This cultural context could make Ikemefuna, especially as an outsider, feel uneasy about the unknown information being exchanged.
Fear of Ostracization or Exclusion: Whispering can be a form of excluding others from a conversation or knowledge. As a young boy and a newcomer to the village, Ikemefuna might be particularly sensitive to feeling left out or ostracized. The hushed tones could signify something he's not supposed to know, further amplifying his anxiety.