(Hitori musuko). Ozu converted to the sound film late, and incorporated the “new” medium into his rigorous style. The Only Son, his first sound feature, has been called by film theorist Noel Burch “his supreme achievement.” The story has an O. Henry–like irony out of which Ozu fashioned one of his most emotional films, “filled with originality, integrity, and the sharpest kind of observation” (Donald Richie). A widowed mother who has worked for years to send her boy to college spends her entire savings on a visit to her “successful” son. He, being unemployed and impoverished, must borrow money to put her up. Ozu's use of sound highlights the industrial backdrop against which the story is set, from the mother's simple grinding of rice flour to the hum of factory machines.