*I'll wait for the obligatory jokes about the female voice, hot air, amount of said hot air, et cetera, et cetera....
Done now? Good.
Anyway, in the month-long study, the Royal Horticultural Society recorded ten people reading from either literary or scientific works, both men and women, and played their voices through a set of headphones that was attached to each tomato plant's pot (so, one tomato plant per person.) The same tomato variety was used, same soil, same care regimen, etc. They also included two plants that were not read to as a control. At the end of the month, the plants that had been attached to female voices grew an average of an inch taller than those attached to a male voice. The overall winning tomato listened to Sarah Darwin, great-great granddaughter of Charles Darwin. Her plant grew approximately two inches taller than the rest.
What did Ms. Darwin read to her tomato plant? On the Origin of Species.
Asked about her plant's favorable response to her voice and selection, Sarah Darwin commented, "I'm not sure if it's my dulcet tones or the text that I read from On the Origin of Species that made the plant sit up and listen, but either way I think it is great fun and I'm proud of my new title."
Researchers went into the study with the idea that the male voice would make the plants grow faster, and were surprised with the results. They said that they are unsure why the female voice worked better, saying that it could be that women may have a greater range of pitch or tone that affects the sound waves that hit the plant, and that sound, just like any other environmental factor, has an effect on plant growth.