Gerhard Schröder | Gerhard Richter | Gerhard Müller (rower) | Gerhard Müller | Gerhard von Scharnhorst | Gerhard Munthe | Gerhard Zucker | Gerhard | Gerhard Markson | Gerhard Gentzen | Roberto Gerhard | Herman Gerhard Gade | Gerhard von Rad | Gerhard V of Jülich | Gerhard Riedmann | Gerhard Präsent | Gerhard Munthe (painter) | Gerhard Maria Wagner | Gerhard Ludwig Müller | Gerhard Heinrich Dieke | Gerhard Hanappi | Gerhard Frey | Gerhard Christoph von Krogh | Ken Gerhard | Heinz-Gerhard Haupt | Gerhard von Kügelgen | Gerhard von Graevenitz | Gerhard VI of Jülich, Count of Berg and Ravensberg | Gerhard VI | Gerhard Stahl |
Electret materials have been known since the 1920s and were proposed as condenser microphone elements several times, but they were considered impractical until the foil electret type was invented at Bell Laboratories in 1962 by Gerhard Sessler and James West, using a thin metallized Teflon foil.