Acoustic transducers; electroacoustic transducers; electromechanical transducers for converting electrical signals to corresponding mechanical vibrations; electronic and electrical sound production apparatus and instruments incorporating acoustic, electroacoustic and electromechanical transducers that convert electrical signal energy into acoustical energy, namely, electronic and electrical sound production apparatuses and instruments incorporating loudspeakers or acoustic radiators used to reproduce sound by generating acoustic waves from electrical signals; electronic and electrical sound production apparatus and instruments incorporating an acoustic, electroacoustic and electromechanical transducer which is actuated by sound waves and delivers essentially equivalent electric waves, namely, electronic and electrical sound production apparatuses and instruments that incorporate a microphone or other acoustic receiver used to convert sound from acoustic waves into electrical signals