From the earliest work in sound reproduction, it has been known that horn loaded transducers provide the most efficient means of coupling the listening environment to the sound source. The horn acts as a transformer, converting high pressure, low velocity acoustic air movements into low pressure, high velocity sound radiation. Horns can be seen way back to earlier civilisations being used amplify and broadcast sounds. Conch shells and ram’s horns, later, Tibetan horns and alpenhorns are all based on the same principle as their modern counterparts. They convert a sound at the small throat into a broad, fast moving integrated wave front leaving the horn mouth that travels long distances to the ear of the listener.
The most familiar image of a horn in use is the “His Master’s Voice” painting employed by the Gramophone Company at the beginning of the 20th century to popularise their new product over the older phonograph, invented by Thomas Edison.