1
Hiroshi Ono: Piezoelectric bone conductive in ear voice sounds transmitting and receiving apparatus. Frank J Jordan, April 17, 1979: US04150262 (203 worldwide citation)

A voice sound transmitting and receiving apparatus suitable for the use under noisy circumstances and designed to be inserted into the external auditory canal of a user for attaining the voice sound transmitting and receiving operation using the vibrations of the external auditory canal wall.


2
Piezoelectric bone conductive in ear voice sounds transmitting and receiving apparatus. Hiroshi Ono, June 13, 1980: FR2441983-A1 (2 worldwide citation)

A voice sound transmitting and receiving apparatus suitable for the use under noisy circumstances and designed to be inserted into the external auditory canal of a user for attaining the voice sound transmitting and receiving operation using the vibrations of the external auditory canal wall.