CHAPTER III

I. Review of Related Literature and Studies

In daily life, many phenomena supporting the claim that plants acknowledge and respond to music have been observed. For example, in the Dai minority autonomy in Xishuang Banna of China, there is a type of legume grass whose 2 small symmetric leaves on its main leaf cushion dance rhythmically to harmonious music. Interestingly, it does not show any response if blown or caressed with hands. (Hou and Mooneyham, 1999)
Therefore, it is natural to assume that the effects of music, and thus sound, on plants, might be beneficial, instead of merely “dancing”. A good gauge of this is plant growth, which can be measured in a number of ways: number, size and weight of fruits, storage duration and photosynthetic ability of the leaves, among other methods.
Researches on these variables have been carried out since the first commercial experiment in 1972 by Charnoe, who studied the effects of sound waves on budding of barley. Subsequently, Carlson of the United States of America treated various crops and vegetables with high frequency sound waves (Spillane, 1991), and the Xian Tuo company in Osaka, Japan, has treated vegetables with classical music (Xiao Hai, 1990).
Reports of the growth of many record-breaking fruits have also been attributed to music. For example, French scientists have cultivated a 2 kilogram tomato, and British scientists have produced a 13 kilogram beet (Hou and Mooneyham, 1999). This technology and field of study have come to be known as acoustic biology.
However, most of these reports lack support from advanced scientific theories and precise instruments to measure the actual changes in plants.
Many of these reports attribute the plant’s ability to “sense” music to its natural “sound system”, or the meridian system, similar to those found in animals, as demonstrated by Hou and Li. This system is based on the ancient Chinese meridian theory. Based on this theory developed in Tsing Hua University in Beijing, the He-Ne laser Doppler vibration instrument was invented (Luan and Hou, 1993). By means of this instrument, spontaneous and external sound wave frequencies of plants have been measured, spectrum analysis has been performed, and special wave generators with 7 frequencies between twenty to two thousand hertz have been built.
Hou et al have measured the meridian characteristics of phylodendron plants and found that the sound waves emitted from the plant are in the range of 10 to 240 hertz, with the peak being in the range of 50 to 100 hertz. They have also found that when frequencies of 80, 100 and 150 hertz were used to stimulate the plants, 100 hertz had the best results, increasing the plant’s produced wave forms from 7 dB to 22 dB.
This is probably because of the stimulation of the meridian system of the plant at the range it is most “vocal” in, 100 hertz, which causes the plants to increase their output at that frequency threefold . As Beasley (1978) once observed: “If two independent systems, both having the same nature occurring frequency, are joined together in a harmonious phase, resonance occurs with the result that their maximum and minimum values are reached simultaneously, both systems vibrate in unison. Under these conditions, the resulting wave from the values created by the union of the two frequencies exceeds that which either could produce independently.” Thus, the increase in plant growth is explained by the positive stimulation of the plant meridian system.
If music is involved, the “consciousness” of plants will play a part in the discerning of different types of music. This has to hold true if the claims of certain horticulturists that classical has a “soothing” effect on plants and therefore helps them to grow better. This plant “consciousness” is best described scientifically as the plant meridian system, which is very similar to the human meridian system.
The meridian system, in brief, is a Chinese system closely linked to acupuncture. It proposes that the body (in the case of humans) is connected by a series of pathways, or meridians, in which flows the body’s different energies (the yin and the yang) . Theses energies are collectively known as “qi”. It is believed that the stimulation of these meridian points can enhance the stability of the related meridian, and thus, improve the well being of the person (Shang, 1996).
Therefore, it is possible to stimulate the meridians of plants by playing certain frequencies, creating a more productive plant. This is shown in the experiment on tomato plants conducted by Hou and Mooneyham using agri-wave technology, the fruits showed an increase in the amount of nutrients (up to 92%), as well as accelerated ripening and heavier fresh weight (up to 30%).
Theses above results thus show that sound, and therefore in turn music, can play a part in increasing the growth of plants in general . Although the actual reason for the accelerated growth has yet to be discovered, it is partly explained in the relation to the stimulation of the plant’s meridian system . More scientific studies need to be done to show the viability of such a technology, as the world needs every new technology it can get it’s hands on, no matter how “unscientific” it is, to increase crop production worldwide . If perfected, agri-wave technology can be a cheap and easy way to feed the hungry mouths of the world .
In 1973, a woman named Dorothy Retallack published a small book called The Sound of Music and Plants. Her book detailed experiments that she had been conducting at the Colorado Woman’s College in Denver using the school’s three Biotronic Control Chambers. Mrs. Retallack placed plants in each chamber and speakers through which she played sounds and particular styles of music. She watched the plants and recorded their progress daily. She was astounded at what she discovered.
Her first experiment was to simply play a constant tone. In the first of the three chambers, she played a steady tone continuously for eight hours. In the second, she played the tone for three hours intermittently, and in the third chamber, she played no tone at all. The plants in the first chamber, with the constant tone, died within fourteen days. The plants in the second chamber grew abundantly and were extremely healthy, even more so than the plants in the third chamber. This was a very interesting outcome, very similar to the results that were obtained from experiments performed by the Muzak Corporation in the early 1940s to determine the effect of "background music" on factory workers. When music was played continuously, the workers were more fatigued and less productive, when played for several hours only, several times a day; the workers were more productive, and more alert and attentive than when no music was played.
For her next experiment, Mrs. Retallack used two chambers (and fresh plants). She placed radios in each chamber. In one chamber, the radio was tuned to a local rock station, and in the other the radio played a station that featured soothing "middle-of-the-road" music. Only three hours of music was played in each chamber. On the fifth day, she began noticing drastic changes. In the chamber with the soothing music, the plants were growing healthily and their stems were starting to bend towards the radio! In the rock chamber, half the plants had small leaves and had grown gangly, while the others were stunted. After two weeks, the plants in the soothing-music chamber were uniform in size, lush and green, and were leaning between 15 and 20 degrees toward the radio. The plants in the rock chamber had grown extremely tall and were drooping, the blooms had faded and the stems were bending away from the radio. On the sixteenth day, all but a few plants in the rock chamber were in the last stages of dying. In the other chamber, the plants were alive, beautiful, and growing abundantly.
Mrs. Retallack’s next experiment was to create a tape of rock music by Jimi Hendrix, Vanilla Fudge, and Led Zeppelin. Again, the plants turned away from the music. Thinking maybe it was the percussion in the rock music that was causing the plants to lean away from the speakers, she performed an experiment playing a song that was performed on steel drums. The plants in this experiment leaned just slightly away from the speaker; however not as extremely as did the plants in the rock chambers. When she performed the experiment again, this time with the same song played by strings, the plants bent towards the speaker.
Next Mrs. Retallack tried another experiment again using the three chambers. In one chamber she played North Indian classical music performed by sitar and tabla, in another she played Bach organ music, and in the third, no music was played. The plants "liked" the North Indian classical music the best. In both the Bach and sitar chambers, the plants leaned toward the speakers, but he plants in the Indian music chamber leaned toward the speakers the most.

She went on to experiment with other types of music. The plants showed no reaction at all to country and western music, similarly to those in silent chambers. However, the plants "liked" the jazz that she played them. She tried an experiment using rock in one chamber, and "modern" (dischordant) classical music of negative composers Arnold Schönberg and Anton Webern in another. The plants in the rock chamber leaned 30 to 70 degrees away from the speakers and the plants in the modern classical chamber leaned 10 to 15 degrees away.