Study of Soundscape Design Incorporating Sound Instrument into Mini-Plant Factory

A mini-plant factory was originally developed as a kit for growing vegetable and ornamental plants indoors. However, recently, it has become worldwide popular to be installed in public spaces such as schools, hospitals, offices, and airport to improve the indoor environments as well as alleviating human stress. Because opportunities for humans living in the city to interact with the natural greens are decreased, and mental stress is increasing. In this study, we have installed a sound generating instrument into the equipment of the mini-plant factory, and observed sound pressure level in a room. The nutrient solution is necessary for a plant factory to grow plants, but these devices have fatal mechanical noise from electric motors and pumps to circulate the nutrient solution. As a first step, we dropped the droplets of the nutrient solution in the pipes to make the sound by the instrument. The sound pressure level near the device was about 70 dB(A), and about 50 dB(A) was observed at a position of 2m away from the source through the sound outlet of the device. Besides, the frequency characteristics of the sound was widely flat, and components of the high frequency band was sufficiently rich.