acoustical network capacitor speaker coaxial speaker cone crossover network diaphragm dynamic speaker earphone electrodynamic speaker electromagnetic speaker electrostatic speaker excited-field speaker full-fidelity speaker headphone high-fidelity speaker high-frequency speaker horn loudspeaker low-frequency speaker midrange speaker monorange speaker moving-coil speaker permanent magnet speaker radiophone radiotelephone speaker speaker system speaker unit triaxial speaker tweeter voice coil wireless wireless telephone woofer