Found in a garden shed where it had been for at least the last thirty years, this WW2 British military throat mic looks a bit sad and dilapidated. The paint is falling off and the steel fittings are rusting, the elastic is past its best, and a hungry woodworm has been drilling into the crumbling leather. So imagine my surprise when I plugged it in and it immediately burst into life!
The M.T.L.L. No 2 was used by the RAF and by the army. The mic was worn around the neck and was designed to pick up vibrations direct from the voice box. The two leather covered sensors were pressed against either side of the throat. The great advantage of the throat mic was that it could be used effectively in very noisy environments, such as inside a tank or an aircraft in combat. Even loud sounds around the wearer would be largely rejected. Although the audio quality is not fabulous, speech has a high degree of intelligibility.
This view below is of the back of one of the sensors with the plastic cover removed. Inside there is a magnet, the polarity of which is marked on the metal case ‘N’ and ‘S’. The wires are identified with red and blue cotton thread. (Hot and cold?)
Below, the strip of steel which picks up vibrations from the throat is sitting on top of the coils and magnet. This assembly is held in place by the leather covering. The result of this ingenious arrangement is a small electrical (audio) output signal appearing at the red and blue wires.
It would be hard to exaggerate the importance of military communications during World War 2 and the crucial role played by the M.T.L.L. No 2 throat microphone.