Although not generally the centerpiece of a Japanese militaria collection, Japanese Second World War earplugs are a quite interesting and uncommon addition to one’s collection. It has been my personal experience that these earplugs are usually referred to by two different names: mosquito earplugs, or artillery earplugs. In my opinion, neither of these are correct.
It is absolutely the case that the Japanese military served in areas heavily infested with mosquitos, both in Southeast Asia and especially in Mongolia. In response to the threat of malaria as well as the annoyance of mosquitos, the Japanese military did develop equipment to protect soldiers from mosquito bites, most notably hoods, gloves, and nets, and insect repellent. However, if the mosquitos were bad enough to require earplugs to prevent them getting in your ears, wouldn’t you just want to use a hood to protect your entire head?
It is reasonable to assume that artillery crews would have received these ear plugs over most Japanese soldiers. Artillerymen would be subjected to constant loud noise and would benefit from some sort of hearing protection; However, there is no direct evidence suggesting that they were designed solely for artillerymen.
Japanese earplugs were issued in a beechwood box measuring 56mm long, 30mm high, and 22mm in width. The lid rotates counterclockwise on a center slot head screw and washer to reveal two inner compartments containing the earplugs. Interestingly, the body and lid have corresponding angled cuts on one side. These cuts allow the lid to only open counterclockwise and provide just enough tension on the lid to prevent it opening unintentionally. Storage boxes are marked in Japanese Kanji with, “Ear Safeguard Instrument” on one side, and either the Kanji characters for large (大, Ōkī) or small (小, Chīsai) on the reverse
side. It is quite common to find earplug boxes that have been marked with either unit numbers or names on the bottom.
The earplugs themselves are a multi-part construction consisting of the body, mesh screen, and lower disk. The main body is hollow, and cast in black Bakelite, a material similar to plastic. It appears that the earplug bodies are cast in a two-part mold that leaves a seam running vertically on either side of the plugs. This seam is then sanded or filed off. The small size earplugs measure 17mm in length and 12mm in diameter at the base. At the time of writing this article, I only have the small size in my collection, so the large size dimensions are still to be determined. If I ever manage to snag a large size, I will update this article with their dimensions.
The mesh screen is quite fine and intended to dissipate sound while still allowing the user to hear. The screen is held in place by a Bakelite disk that is most likely glued into place. This disk has a center hole measuring 6mm in diameter and allows sound to pass through. It is likely that the “Mosquito” earplug name comes from the use of this mesh screen.
Earplugs are cast with size markings on the outer body for handy identification and some have been observed with knurled rings cast into the upper and lower sections of the plugs. These knurlings are probably intended to make removal easier.
These earplugs are covered very briefly in Agustin Saiz book, Heitai. In his book, Saiz claims that these earplugs were in constant short supply, and when stocks finally reached units, they were snatched up by officers and NCO’s forcing the regular Japanese soldier to make use of improvised earplugs. While this may very well be true, I have found no direct accounts of this happening, although it could explain why these sets are commonly found with names written on the cases.
These Japanese earplugs are somewhat uncommon but not particularly rare on the Japanese collector’s market. When available, they generally command prices of around $75-$100 USD. Some may have a hard time paying $100 for earplugs, but they make for a great addition to any Japanese collection and are an interesting and uncommon talking point.