Ultrasound reproduction appliances, namely, ultrasound loudspeakers, ultrasound transducers; electric, electronic and optical measuring, signaling, checking supervision apparatus and instruments, namely, ultrasonic transproducers, ultrasonic arrays, amplifiers, modulators; apparatus and instruments for recording audio signals and parts thereof, namely, microphones, dynamic microphones, condenser microphones, electret microphones, head strap microphones, swan- neck microphones, directional tub...

APPARATUS FOR THE AID OF MARINE NAVIGATION OF THE TYPE EMITTING AUDIBLE SIGNALS

MARINE NAVIGATIONAL AID DEVICE OF THE TYPE EMITTING AUDIBLE SIGNALS