Synonyms to ear trumpet

amplifier, attenuator, audio-frequency tube, ballast regulator, ballast tube, beam-switching tube, convertor, current regulator, damper, detector, discriminator, doubler, electronic hearing aid, focus tube, generator, hard-of-hearing aid, hearing aid, iconoscope, inverter, limiter, local-oscillator tube, megaphone, mixer tube, modulator, multiplier, multipurpose tube, multivibrator, oscillator, output tube, phase inverter, picture tube, power tube, preamp, preamplifier, pulse generator, radio-frequency tube, receiving tube, rectifier tube, regulator, repeater, speaking trumpet, stethoscope, transducer, transistor hearing aid, trigger tube, vacuum-tube hearing aid