An earplug of the type that has a stem (12) and a plurality of flanges (21 23), is constructed to be stiff enough to be easily inserted into the ear canal, and to thereafter press with minimal force against the walls of the ear canal for comfort. The earplug is molded of an elastomeric material whose stiffness decreases considerably, such as at least 4%, when it is warmed from room temperature (about 72.degree. F.) to ear canal temperature (about 100.degree. F.). Each flange has a radially inner portion (52) that extends straight at an angle (B) that is within 15.degree. of a radial direction (62) (a direction perpendicular to the stem axis), and has a radially outer portion (54) that extends straight and at an angle (C) that is within 20.degree. of an axial direction (66).