Clairaudience: The Philosophy of Its Expression examines the purported psychic ability to hear messages beyond ordinary physical sound—what the author calls “supernormal hearing.” In twelve structured lessons, Grumbine defines clairaudience, explores its historical, philosophical and spiritual context, and offers guided experiments to cultivate it. He discusses concepts like objective versus subjective mind, spirit communication, and differentiates dependent from independent voices in mediumship. The book blends early?20th?century spiritualism with practical exercises aimed at developing inner stillness and receptivity to unseen intelligences.