Abstract
A rest room is required in comfortable living space. There's a tank less toilet going around because a space is excluded recently. But toilet jet that is specific for tank less toilet becomes a problem for the living environment noise. So this paper describes the improvement of sound quality of toilet jet. An acrylic board model is made for taking a picture of the flushing mechanism by a high-speed video camera. It is found that the jet noise generates many bubbles involved in water current, and in order to reduce noise, the form of a nozzle is changed. For the result is evaluated, the relationship between sound quality of toilet jet and human sensation is investigated by using sound metrics and vital data.