As a spiritual basis, Shin Tao(Sorry, Chinese characters for Shinto.) thought is that sound is the energy that moves the universe. Thus, O'sensei thought music was likened to Aikido from a spiritual basis. :-D
I'm not disputing the central role of kotodama in OSensei's spiritualism (which I believe is not mainstream shinto but omoto-kyo) rather referring to him as a shinto priest.