3M's E-A-RCAL Acoustical Laboratory, established in 1979, has offered contract testing since 1992. The principal service offered is the measurement of the real-ear attenuation at threshold (REAT) of hearing protection devices (HPDs). Additional services include objective hearing protector and earphone measurements utilizing either KEMAR or the ANSI S12.42-2010 or ISO/TR 4869-3 acoustical test fixtures, or miniature microphones and/or probe microphones placed in real ears.