A world of investigation into the relationship between plants and soundwaves is going on; bioacoustics, sound frequency flower essence, utlrasound encouraged growing, the interesting translation of electronic signals from plants into sound and music, shamanic ideas and onwards forever. Research really does indicates that sound is an integral aspect to plant life.
Recently scientists Dr Monica Gagliano (University of Western Australia), Professor Daniel Robert (University of Bristol) and Professor Stephen Mancuso (University of Florence) found that young corn plants communicate via clicking noises at a frequency of around 220Hz. The young corn roots also responded when suspended in water to a constant tone of 220Hz by moving their tips toward the sound source. See more details here:
Other interesting facts about the frequency of 220Hz: it is within the range of female alto singer, it is the frequency of the A string on a cello and also in some circles believed it to be the healing frequency for lungs.