Associate Professor OBATAYA Eiichi, Faculty of Life and Environmental Sciences

Various musical instruments such as violins, guitars, marimbas and recorders are made of wood. Their beautiful sounds are achieved by the characteristics of wood: lightweight, fast sound propagation, anisotropic nature and so on. No matter how high-tech, no synthetic material can substitute wood at this time. Focusing on the kind of wood used in stringed and wind instruments, Prof. Obataya dedicates his studies to the extraction of even higher quality and value enhancement.

There are various types of wood, all with different qualities. There are even differences in quality between pieces of wood of the same type. Skilled instrument makers determine the quality of a piece of wood by watching its surface and listening to the sound by tapping. In actuality though, the quality of wood is determined according to scientific factors such as the anatomical feature of tissues and the fine structure of the cell walls in nanometer scale. Having turned his attention to wood for use in instruments, Prof. Obataya studies and evaluates wood qualities best suited to instruments, and is involved in the development of technologies that enable modification of those qualities.

The value of an instrument is affected less by the wood than by the reputation of the instrument maker and by the instrument's perceived beauty. Also, the value of an instrument increases with its age. For that reason, fresh wood is sometimes deliberately stained to give instruments an antique appearance. However, these superficial measures can only be regarded as unnatural. That is why Prof. Obataya studies thermal treatment of wood. It has been known that when wood is heated it darkens the color and induces various chemical changes, creating the appearance and quality of aged wood. Recently, though, it has become possible to faithfully reproduce not just the color but also the acoustic properties of aged wood by regulating temperature and moisture. It is also possible to predict the properties of wood that has aged for several hundred years, so the process is also valuable for the restoration of old wooden cultural properties.

Meanwhile, wood used in instruments is facing a serious crisis. Wood from the tree known as grenadilla, of African origin and with a central section colored deep black, is used for the cylinders of woodwind instruments. Grenadilla is heavy and has primarily been used for clarinets, as it is so strong that metal parts can be driven into the wood without breaking it. Some years ago, the tree was listed as an endangered species and its international trade regulated according to the Convention on International Trade in Endangered Species of Wild Fauna and Flora, or CITES. Similarly endangered is rosewood, used in making recorders, erhu and marimbas, and there is reason to fear these woods may become unobtainable. As matters stand, many instruments will become impossible to produce in the near future. As these instruments are unable to produce the same sounds if made of materials other than wood, research has begun into finding substitute woods with similar characteristics.

To address this issue, those involved are using forest resources at hand rather than attempting cultivar improvement. A lightweight wood substitute for grenadilla is treated so that the wood becomes heavier and harder. The treatment method is extremely simple. As wood is a cellular material, it can be densified by folding the cell walls under compression,making it so heavy that it sinks in water. This is not a new technique, but moisture has been the complicating factor when it is used as a material for woodwind instruments. If the wood is merely compressed, it soon recovers its original shape when soaked in water. Particularly in the case of woodwind instruments, the shape of the instrument changes with player's breath and saliva, and it causes serious problems in playing. Prof. Obataya dedicates himself to developing a special process to achieve extremely high dimensional stability under repeated wetting and drying. In the near future, Japanese wood and technology may change the history of material in wooden musical instruments where foreign wood has been used for long time.

Prof. Obataya first took an interest in wood as a graduate student. Intent on becoming a teacher, he was enrolled in the faculty of education. However, in his master's degree program he found it fascinating to study the changes in tone produced by moistening clarinet reeds in water, and so for his doctorate program he switched to the faculty of agriculture and began studying wood in earnest. Prof. Obataya played the clarinet, and has continued to make the study of wood as a material for musical instruments his primary focus. Research into wood as a building material is common, but researchers such as Prof. Obataya who specialize in musical instruments are rare, making his work valuable.

Japan has abundant forestry resources. Rather than worry about them disappearing, we must make active use of these resources and manage them properly. It's possible for the value of wood to be multiplied by the hundreds if no effort is spared in carefully cultivating trees and processing the wood. The fact that wood can be used for a long time makes it environmentally friendly. Some people think that wood is easily degraded by fungi and rot, but this is not true. If we take care of humidity to keep wood dry, it will show excellent durability and stability. Horyu-ji Temple is known as the world's oldest wooden structure, with a history dating back more than 1,400 years. The coffin of Tutankhamun too was made of wood, and is on display in a museum. Compared to functional materials such as ceramics and plastics, wood has a plain image, but it also has immeasurable potential.

Being able to hear beautiful sounds produced by valuable musical instruments has a great psychological effect. However, it is not from that perspective that Prof. Obataya carries out his research, but rather from the standpoint of materials technology. He seeks to apprehend universally pleasant sounds and high-quality materials.

Measuring the vibration characteristics of a piece of wood

Article by Science Communicator at the Office of Public Relations