Public toilets in Japan are arguably world-famous for their high standards of cleanliness as well as the technology that goes into them. Electronic spray toilets are so sophisticated and complex that the Japan Sanitary Equipment Industry Association found the need to revise the symbols on the buttons to more foreigner-friendly versions. At times, the gadgets go a bit haywire, causing problems for unsuspecting users, but for the most part, they are reliable and convenient.

One feature which is practically unique to Japanese toilets is a device, either embedded in the washlet control panel or attached to the wall, which generates a sound to hide or drown out the noise of urination.

Before the 1980s, bathroom users, mostly women, would flush the toilet to achieve this effect. However, since this needlessly wasted water, a more environmentally-friendly solution was called for. The most famous device, manufactured by toilet brand Toto, is called Otohime (literally, "sound princess").

While sound generators completely resolved the environmental problem, they only partially alleviated the presumed root cause of embarrassment since the sound is not truly eliminated. Many Japanese people push the button with the understanding that it is expected as a polite gesture indicating to anyone within earshot that you are showing consideration, even if your actions are not entirely effective.

Home product maker Lixil consulted with electronic music instrument maker Roland to address this lingering deficiency in the existing technology, and together, they invented a new device, the "Sound Decorator":

Unlike existing devices which merely add a new sound to the original sound, the "Sound Decorator" uses Roland's expertise in electronic sound engineering to generate a sound pattern that actually makes the original sound more difficult to hear.

As the illustration in their press release explains, the sound of flowing water (toilet flushing) produced by previous toilet devices has a different wavelength than the sound of urination, and this difference is particularly jarring in the wavelength band between 400 and 1,000 hertz. By contrast, "Sound Decorator" creates a specially engineered sound which has a very similar wavelength to the sound of urination. Through what is known as the "auditory masking" effect, the stronger wavelength neutralizes the weaker one, and the unwanted sound is effectively neutralized.

But what does it actually sound like when you activate the device? Apparently, it is a relaxing sound that evokes a forest, with a babbling brook and small birds chirping.

Lixil will begin selling their "Sound Decorator" devices from tomorrow, February 1st. They will come in two versions, one in which the sound is activated by a motion sensor when you bring your hand close to the panel, and another in which the sound is automatically generated when you approach the toilet.

With the "Sound Decorator," you can now relax and go with the flow, confident that your personal music stream remains personal.

No word yet on what happens when you drop the bass. Maybe they'll have a solution in a future version?