remarkably decreasing the pressure difference between the inside of the external auditory canal and the external atmosphere as well as preventing leakage of sound causing so-called howling.
In order to realize this object, the present invention provides an ear plug to be interted into the external auditory canal, having a compressible sleeve member and a core member attached therein, the improvement in which plural projections or a single projection are formed intermittently or continuously on an exterior of the core member, and vent is formed through or along the projection to make the external auditory canal communicate with the external atmosphere when inserted into the external auditory canal.
According to the present invention, the projections are formed on the exterior of the core member and the vent is defined throughor along the projection to make the external auditory canal communicate with the external atmosphere, so as to lengthen a communicating passage or vent to an effective degree for remarkably decreasing only the pressure difference between an inside of the external auditory canal and the external atmosphere as well as preventing leakage of sound causing so-called howling.
In the present invention, it is preferable that an innermost vent is formed through an innermost projection of the intermittently formed projections or through an inner end portion of the core member to open into the external auditory canal, other vents are formed through other respective projections, and an outermost vent is formed through an outer end portion of the core member to open into the external atmosphere.
In this case, the vents