Corn is authentically American. A member of the grass family, it was first domesticated from a wild grain several thousand years ago by Aztec and Mayan Indians in Mexico and Central America. The first corn was a loose-podded variety that looked like the seed head at the top of wheat stalks. The kernels were small and each covered by a hull. Central and South American peoples came to depend so heavily on corn — or maize — that they devised some of the earliest calendars just to keep track of their corn planting and harvesting schedules.

Eventually, corn’s popularity spread to North America. By the time the first European settlers arrived on this continent, corn was the chief food crop of the native Indians. The colonists quickly learned how to grow corn and enthusiastically adopted the new staple. In fact, much of the early fighting that took place between the settlers and the Indians was over cornfields. Today, the cornfields of Nebraska and elsewhere in the world actually make sounds of growing.  Click on the picture to the left and listen to the corn grow. 

In 1620, Sir Matthew Lister introduced the rhubarb plant (native to Mongolia) to England for the first time, where it was praised for its medicinal qualities. It wasn’t until the 1780s that rhubarb was used in pies as a substitute for other fruits. In the early 1800s, the growers of the Rhubarb Triangle developed “forcing,” which enabled them to produce rhubarb in much greater quantities than ever before.  Basically, they allow the rhubarb to grow naturally in a field without harvesting for two years. During this time, the plants are storing energy from the sun in their roots in the form of carbohydrates. After this period, usually in the winter months, the rhubarb is moved into a heated shed which is kept in complete darkness. The supplied heat means they no longer need to use any of their stored energy to make leaves (which turn a sickly yellow-green color), so all of it goes into making the stalk larger (and sweeter).  This “forcing” is so successful that you can actually hear the rhubarb growing if you go into the sheds. The buds cracking open is what makes the sound, and there is said to be a constant creaking during growing season. In addition, the rhubarb has to be gathered in very low light, usually candlelight, because the plants are so sensitive to light that the “forcing” would stop.  Listen to the sound of Rhubarb growing in the Rhubarb Triangle of England by clicking on the picture.

Of course trees have been around since the beginning of time.  In Germany, using Ulmus glabra (elm tree), Lashimke et al (2004) revealed that acoustic emissions from plants do not necessarily occur in conjunction with water stress. The waveforms in the various signals show that acoustic emissions may possibly be generated by still unknown hydraulic events, more complex than cavitation.  According to Maeder (2017) plant physiologists have known for several decades that plants emit sounds.  He feels that bigger part of these ‘crackling’ or ‘whispering’ sounds emitted by trees [you can listen to the sounds of a Scots Pine tree at this web site] are of transpiratory/hydraulic origin and are therefore related to the circulation of water and air within the plant as part of the transpiration process [the sonogram to the right is of these scots pine emissions]. The frequencies of the loudest acoustic emissions (the so-called cavitation pulses) lie mostly in the ultrasonic range, depending on the species-specific characteristics of plant tissues.

There is something about those Nebraska cornfields, the fields of the Rhubarb triangle of Leeds, England, the elm trees of Germany , or the Scots pines that make eerie noises. Farmers worldwide have long told the story that “on a quiet night you can hear the corn [or rhubarb, or even trees] growing”.  Likely there needs to be special equipment to really hear plants and trees, but they do make an acoustic signature through their emissions.  

While may seem a bit like something out of a Stephen King movie where children, animals or others are lurking in the fields or talking through these plants, there is now evidence that supports their is quite an emittance of noise by plants while growing.  

 

References:

Cook, D., (2016).  Acoustic Emissions Techniques to Explore Corn Stalk Growth and Breakage. Presentation to the 172nd Acoustical Society of America Meeting, Honolulu, Hawaii, November 28,

     December 1, 2016.  Retrieved July 4, 2017.

Laschimke, R., Sigmaringen, F., Burger, M. & Vallen, H. (2004).  Acoustic emissions from transpiring plants – new results and conclusions.  NDT Net. Retrieved July 4, 2017.

Van Duisen, M., (2013).  Rhubarb grows so fast you can hear it.  Knowledge Nuts. Retrieved July 4, 2017.

 

Videos:

Cook, D., McMechan, J.,  & Elmore, R., (2016).  Listen and Watch Corn Grow.  YouTube.com. New York University, Abu Dhabi, University of Nebraska.  Retrieved July 4, 2017.

Ludgood, D., (2015).  Sounds Dangerous, Listen to Rhubarb.  Retrieved July 4, 2017.

 

 

According to Lentin (2014), three of the five noisiest cities in the world are in India, Mumbai (formerly Bombay), Kolkata (Calcutta), and Delhi.  These are highly populated cities, with about 13 million, 14.3 million and 18 million people respectively.  Known as the entertainment, commercial fashion and financial centers for India, they all have severe city traffic and overpopulation, leading to noise levels of over 100 decibels. Mumbai has been declared the noisiest city in the world in numerous studies. The worst noise offenders for all  Indian cities are the continuous construction, loudspeakers, firecrackers, festivals, honking, rickshaws and taxis. Other cities in the world with high noise levels include Cairo, Tokyo, Madrid, Buenos Aires, and Shanghai.  

Noise is not only disturbing, it’s dangerous to mankind as it may harm the activity or balance of human or animal life. The main sources of most outdoor noise worldwide are machines and transportation systemsmotor vehicles engines, aircraft, and trains.  Outdoor noise is summarized by the word environmental noise. Poor urban planning may give rise to noise pollution, since side-by-side industrial and residential buildings can result in noise pollution in the residential areas. Documented problems associated with urban noise go back as far as Ancient Rome.

New York City is the loudest city in North America and, according to studies, the 7th loudest city in the world. NYC residents are often looking for ways to soundproof their homes, offices, nurseries, dorms and elsewhere to live and work in more peaceful and productive environments.  Although NYC is currently the loudest in Americ, Los Angeles, Chicago, and Houston are probably only a few decibels behind. While noise-induced hearing loss can be caused by outside (e.g. trains) or inside (e.g. music) noise, there are also other issues that are caused by excess noise, such as an increased incidence of coronary artery disease in humans. In animals, noise can increase the risk of death by altering predator or prey detection and avoidance, interfere with reproduction and navigation, and contribute to permanent hearing loss. 

George Prochnik’s 2010 book, entitled In the Pursuit of Silence, investigated the unexpected paradoxes at the heart of our relationship with sound: we create noise in order to soundproof ourselves, and we create noise by clamoring for silence. There is a difference between mere noise control and genuine silence, and Prochnik makes an eloquent case for the latter, whether in the form of personal contemplation or communal spaces of tranquility.  He admits to loving quiet, to relishing conversations without straining to hear, and looking up from a book he is reading without being assaulted by the sound of television news broadcasts. He also feels that one of the most bothersome things about noise pollution in these times is that sound imposes a narrative on you. Prochnik cites the silence of a Quaker meeting, the stillness of a walk in space by an astronaut, or the idea of silence as “a break, a rest, a road to reflection, renewal, and personal growth.”

 In his book, Prochnik focuses on the benefits of silence as a precious resource and the different factors which have stimulated us to become such a loud society.  Recently, Patrick Shen created a film which investigated silence around the world. In Pursuit of Silence, takes the viewer on “an immersive cinematic journey around the globe – from a traditional tea ceremony in Kyoto, to the streets of the loudest city on the planet, Mumbai during the wild festival season – and inspires viewers to experience silence and celebrate the wonders of our world. “(Click on the movie poster for a short video on the benefits of silence). 

Prochnik reminds us that absolute silence doesn’t exist but that quiet spaces are essential because they “can inject us with a fertile unknown: a space in which to focus and absorb experience”.

 

References:

 Lentin, M. (2014). Top 10 noisiest cities in the world.  Citiquiet. Retrieved June 27, 2017.

 

Videos:

Chen, P. (2017).  In pursuit of Silence, Exclusive Trailer.  Published June 5, 2017.  You tube.com Retrieved June 27, 2017.