Multitone VPM Vacuum Tube Hearing Aid The Multitone VPM (Vest Pocket Model) was manufactured by the Multitone Electric Co. Ltd. of London, England in 1937. It appears to have been their first wearable hearing aid and featured a clip-on external microphone and an earphone. The VPM model was very small for its time measuring 3¼” by 2½” by 1”. While this example does not have a telecoil, it is reported that the Multitone VPM in 1938 was the first wearable hearing aid to incorporate a telecoil |  | Click picture for larger view | | |   | | | |
