The "digital earplugs" (photo courtesy of King Jim)
The "digital earplugs" (photo courtesy of King Jim)
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King Jim Co Ltd will release "digital earplugs," which reduce noise with a frequency of 300Hz or lower by about 90%, March 7, 2014, in Japan.

The product consists of a main body and earphones equipped with microphones. It has a noise-canceling function that detects noise with the microphones and generates signals with an anti-phase waveform to cancel out the noise.

Noise generated by public conveyances and air conditioning equipment consists mainly of low-frequency components while human voice consists mainly of high-frequency components. King Jim set a threshold at 300Hz and realized the earplugs that cancel out noise having a frequency lower than that and transmit human voice such as in calling someone's name and making an announcement. The noise-canceling level measured by the company is up to -20dB.

The main body measures 64 x 14 x 64mm and weighs 33g (excluding the battery, including the code). It can be continuously used for about 100 hours with an AAA battery cell. The manufacturer's suggested retail price of the product is ¥5,229 (approx US$51.65, including tax). King Jim incubated the product, which was then developed and manufactured by a contractor. King Jim aims to sell 10,000 units of the product within a year after the release.