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Professor Yasuhito Kawai
Professor Yasuhito Kawai,Faculty of Environmental and Urban Engineering
Professor Kawai was the first person to discover the distinctive movement of aerial vibration when sound is transmitted. By applying his innovative“Edge-effect suppression theory,” he was successful in creating a commercial noise barrier edge device to control noise pollution emanating from highways.
 

Professor Kawai made a discovery 30 years ago that culminated in his theory of “sound insulation”

With a penchant for classic music and an interest in spatial acoustics, Professor Kawai studied the theoretical analysis of architectural acoustics at the Faculty of Engineering during his undergraduate days at Kansai University. In graduate school, he noticed a peculiar phenomenon when analyzing acoustic fields around plates using boundary integral equations. He found that when sound waves reached the plate, there was a marked difference in the sound pressure between the front and back, and air particles that transmitted sound were vibrating strongly near the border area. After more than 30 years of exploring how he could apply his theory in a daily life situation, he reached a conclusion in 2009 when researching noise barriers with his students. He hypothesized that narrowing the vibration range at edge of plates would result in reduced noise volume.

Time-integrated flow of sound energy at noise barrier edge

Commercializing groundbreaking“noise insulation equipment”

Sound factor transmitting materials such as a porous substances and cloth serve to reduce noise when placed over the edge of a plate to moderate the velocity of air particles. Professor Kawai discovered this phenomenon after repeated experiments, and he named it “Edge-effect suppression theory.” It was a groundbreaking theory as it was previously thought that noise absorbing walls should be covered by solid materials such as iron. Supported by his friend, Kunihiko Araki, who has extensive experience in designing acoustic features for theaters and concert halls, Professor Kawai initiated the joint development of noise barriers with Nippon Sheet Glass Environment Amenity Company, a leading manufacturer in the industry. After completing verifications on intensity and weather resistance on expressways, an edge device for sound-proof barriers called “Dura-calm E-fX®” was successfully created.

Providing blue sky to expressways and sunshine to construction sites

“Dura-calm E-fX®” is smaller, thinner and lighter in weight but more effective than standard noise buffers, and decreases more than half of the sensory noise. Moreover, the height of a noise barrier equipped with “Dura-calm E-fX®” can be one third shorter than a regular barrier, and provides expressways with sky view factors, open sky, and sense of release. As trial tests on expressways are coming to an end, it is slated for use in controlling noise in other environments such as Shinkansen bullet train tracks. The edge device is now being commercially developed in cooperation with Toda Construction Company, and is already being employed at construction sites to mitigate visual impact in surrounding neighborhoods, as well as for reducing noise pollution. Professor Kawai’s goals of benefitting society through research were realized through reduced noise and the enhanced landscape. Because of its small size, his invention was also successful in reducing construction costs.

The edge device for sound-proof barriers “Dura-calm E-fX(R)”
Professor Yasuhito Kawai, second from left
Photo credit: JST News

Curiosity leads to the betterment of society

Kansai University’s Center for Business, Government and Universities supported Professor Kawai’s research by providing guidance regarding intellectual property such as patent applications, and in applying for the A-STEP system (Adaptable & Seamless Technology Transfer Program through Target-driven R&D) awarded by the Japan Science and Technology Agency. Kansai University advocates social contributions through its educational policy, which is in line with industry-academia-government cooperation ideals. Taking advantage of being a comprehensive university, Kansai University affords students an atmosphere in which they can become cognizant of social needs, and pursue studies freely in a way that can contribute to a better society with the backing of the university’s support systems. Professor Kawai implores his students to be curious without holding stereotypes, and to always be sensitive to how their knowledge and learning can be utilized in the real world. He teaches his charges to create fruitful and useful ideas for the benefit of all.

  • Passion for Research
  • Faculty of Environmental and Urban Engineering
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