The effect of sound on the growth of plants

This project is intended to show how the rate of growth of two different plant species was affected by sounds of varying frequencies. Two plant species, beans and impatiens, were selected because of their relatively fast growing rates. Ambient conditions were regulated by environmental chambers in which the plants were housed. One chamber was used as a control for the plants, and the plants in the other chambers were subjected to sounds of different frequencies at roughly the same sound intensity. Sounds of pure tones and random [wide band] noise were used. The changes in the growth of the plants were monitored every two days for twenty-eight days. Upon completion of the tests, it was observed that optimum plant growth occurred when the plant was exposed to pure tones in which the wavelength coincided with the average of major leaf dimensions. It is suggested that this was due to the scrubbing action of the traversing wave, causing air particle motion on the surface of the leaf; this movement removed the stagnant air layer adjacent to the leaf, thus increasing the transpiration of the plant. It was also noted that the plant growth was less when exposed to random noise.