Ghost Stories/Gakkou no Kaidan (Dubbed) S1/E18

Satsuki's teacher asks her to take up the job of the school announcer. While doing her task, Satsuki realizes that the broadcast room is haunted by the ghost of Akane, a girl who died of a sudden heart attack during a radio show in the old school. Since then, her ghost curses all those who hear her voice and they will die at the sunset of that same day. Satsuki puts her into spiritual sleep by repeating the number four several times (in Japanese culture, "4" is an unlucky number, because "shi", the word for four, is also the word for death), with Hajime finishing the process by ringing the bell that announces the end of the radio transmission.