Hearing aids

• "Audiphone", R.S. Rhodes, US Patent 219828. 1879
• "Support and Hair Covering for Earphones", E.P. Donoher, US Patent 2040246. 1936
• "Hearing Aid Equipment for Confessionals", N.V. Casson, US Patent 2424348. 1945
• "Lady's Hearing Aid Hat Construction", A. Maffris, US Patent 2584896. 1952
• "Hearing Aid", I.H. Cole, US Patent 2977425. 1961
• "Voice Reflector", C.H. McFarlane, US Patent 3155189. 1962
• "Acoustic Transducer", H. D. Robinson et al, US Patent 3513937. 1970

Employing bone conduction. see also "Vibration Transducers"

• "Bone Conduction Hearing Device", E.H. Greibach, US Patent 2127468, 1938
• "Sound Pickup Device", W.C. Eddy, US Patent 2439459, 1948. Smoker's pipe transmits sound via jaw.
• "Bone Conduction Reciever", L.A. Watson, US Patent 2454494, 1948
• "Bone Conduction Unit", H.S. Knowles, US Patent 2459325, 1949
• "Bone Conduction All-In-One Transistor Hearing Aid", H.A. Pearson, US Patent 3030455, 1962

• Two toys employing bone conduction

  • "Sound-transmitting Amusement Device and Method", Filo et al, US Patent 5902167. 1999
  • "Denta-mandibular Sound-transmitting System", Filo et al, US Patent 6115477. 2000