Microwave radiation of frequency 0. The decay is monitored by a testing circuit such as a comparator. The electric device for N printing material cartridges is configured such that the detection current is predetermined threshold value current or more when N printing material cartridges are all mounted inside the holder. To ensure that the localization of auditory events reproduced by this headphone can be controlled selectively, the acoustic baffle in each housing is provided with a first high damping portion which, relative to the center of the sound transducer, covers a region of more than 170 degrees and less than 340 degrees of the midwoofer. A portion of the channel is covered by a bridge member that defines an aperture between and open to adjacent portions of the channel. A related electronic device is also provided.