Total internal reflection optics have an engagement member that mates with a complementary feature on the LED holder. The GaNAlN superlattice mitigates the strain between a GaNsapphire template and a multiple quantum well heterostructure active region, allowing the use of high Al mole fraction in the active region, and therefore emission in the deep UV wavelengths. The swirler includes one fuel tube for gaseous fuel positioned in parallel on each side of a mixing rod in the passage, wherein the fuel tubes are provided with a plurality of diffuser holes distributed along the tube acting as gas injectors for efficiently distributing fuel in a flow of air passing through the swirler passage. A processor determines a contact and coupling condition for the target tissue based at least in part on reactance of the impedance measured by the measurement circuit. If the difference in levels drops below or exceeds the threshold value, the respective hearing device is switched to the telephone mode. The reconstruction, verification and location process may then be repeated, if there are enough remaining packets, until the reconstructed original packets are deemed correct.