Embodiments relate to earmuffs with speakers, and attempt to improve speaker acoustic quality without negatively impacting sound attenuation of the earmuffs. The trench and the conductive metal column and the via have a common axis. In one embodiment, flow control frames carry an IEEE802. In this way, the OS-thread does not access the parameters in the object heap directly while performing the IO operation. 1 of one of array probes 10 are arranged along one side of a rectangular shape of the material being tested, and a plurality of transducers 1. Further, error information that is generated as a result of the automated administration process itself can be stored and made available to the system administrator for review.