Wood Reforming Technology A.R.E.™
Reforming Wood in a Short Period of Time
A.R.E. (Acoustic Resonance Enhancement) is an original wood reforming technology developed by Yamaha. Through precise control of temperature, humidity, and atmospheric pressure, the molecular properties of wood can be manipulated into a more acoustically ideal condition, similar to the molecular characteristics of wooden materials in instruments that have been played for years. A.R.E. is an environmentally friendly technology that does not use any chemicals in its treatment process.
A.R.E. Research Originated in the Development of Violins.
The development of A.R.E. began in the late 1990s with Yamaha’s research to begin manufacturing violins. A violin that is 200 or 300 years old is considered a masterpiece and produces a wonderful sound. As part of our violin manufacturing research, we set a mission to research “wood that sounds good” and to “achieve the same sound quality with young wood as with aged wood”. Wood is subject to changes due to temperature and humidity, and young wood has an angular and hard sound. But, as wood ages, it becomes less susceptible to changes and produces a rounder, deeper, better sound. We believe that this “aging” is one of the key points to improve sound quality, and we considered various methods such as chemical treatment and boiling treatment to accelerate the aging process in a short period of time. Among the many approaches, the safest and most efficient method was to improve sound quality by precisely controlling temperature, humidity, and air pressure.
What are the Characteristics of Wood that can Produce “Good Sound”?
Usually it takes years of playing for strings, such as guitars and violins, to mature to the point where the instrument achieves a great sound. At Yamaha, we have built on research accumulated from over 100 years of piano making and more than 40 years of crafting acoustic guitars, to develop groundbreaking woodworking techniques that are truly revolutionary.
Wood is made up of fibrous cellulose and resinous lignin, and a substance known as hemicellulose that binds these together. When sound vibration is transmitted to a wood board top, non-uniform areas of uncrystallized cellulose interfere with the transmission of vibrations. Hemicellulose acts as an adhesive that binds the cellulose and lignin together. It also prevents surfaces from resonating. In aged wood, the crystallization of cellulose increases and the wood becomes harder in the direction of the grain. On the other hand, the hemicellulose decreases. As it becomes harder in the direction of the grain, wood becomes softer across the grain. This difference in physical properties depending on direction is called “anisotropy”. As the anisotropy of the wood increases, this helps the wood to respond well when an instrument is played, extending the low range, and rapidly decaying the high range. A.R.E. technology was developed by focusing on this characteristic of aged wood.
Applying A.R.E. treatment through a wood panel crystallizes the cellulose, improving its sound transmission. The breakdown of hemicellulose allows the panel to vibrate more easily. These changes give even new wood the same molecular structure as the wood of an instrument that has been played for many years, transforming it into material that resonates beautifully. Just listening to the reverberation of the wood makes it clear. In the video below, you can hear the difference in sound between a normal wood board and a wood board that has been treated with A.R.E. (If you use headphones, you will be able to hear the difference more clearly.)
So what are the characteristics of the “aged wood” that makes this possible? Wood is usually made up of fibrous cellulose and resinous lignin, and a substance called hemicellulose that blends the two together. In old wood, the cellulose crystallizes and becomes harder in the direction of the grain. On the other hand, the hemicellulose decreases, and as a result, the wood tends to shift in the direction of thickness. It becomes harder in the direction of its grain and softer in the direction of its thickness. As the anisotropy of the wood increases, the sound becomes better: the response at the moment of playing is better, the low frequencies are extended, and the high frequencies decay faster. A.R.E. technology was developed by focusing on this characteristic of aged wood.
In the video below, you can hear the difference in sound between a normal board and a board that has been treated with A.R.E.
(If you use headphones, you will be able to hear the difference more clearly.)
You can listen to the performance examples shown in the video by clicking here.
Overview of A.R.E. Treatment
With A.R.E. treatment, the wood is first placed in a cylindrical metal pressure vessel, the internal temperature and humidity are controlled, and the pressure is varied in stages. The treatment is surprisingly quick compared to the time required for the wood to age.
One of the most important aspects of the process is the high-precision control of temperature, humidity, and air pressure, as well as setting the optimal processing volume. Based on our years of knowledge and expertise, we treat the wood by setting the optimal values for processing parameters that will achieve both “good sound” and durability as a musical instrument.
So, what exactly is changing in the wood?
A.R.E. treatment, with its hardening in the direction of the grain and softening in the direction of thickness, increases the extension of the sound in the low frequency range and the rise of the mid-high frequency range. A.R.E. treatment also improves the grain and graininess of the sound, while at the same time reducing the harshness of the sound, resulting in a calm and pleasant tone.
In this way, new wood is transformed into a composition that resembles that of aged wood.
A.R.E. technology is used in wooden musical instruments such as violins, acoustic guitars, and electric basses. A.R.E. technology has also been applied to the stage at Yamaha Ginza Hall. The floor of a hall easily transmits the vibrations of musical instruments, and the material of the hall floor contributes greatly to the sound.
A.R.E. technology is a technology that takes care of wood. Wood is lightweight and easy to work with, and a sustainable supply can be achieved through systematic planting and forest management. In addition, wood is structurally anisotropic, making it an ideal material for musical instruments. This is the reason why many musical instruments are still made of wood, even though many things that were once made of wood, such as building materials and sports equipment, are being replaced by new materials one after another.