The following description is taken from http://www.hearingcenteronline.com/museum.shtml

Ear trumpets were probably early man's first attempt at coping with hearing problems. In pre-historic times, hearing trumpets were simply hollowed-out horns of cows, rams or other animals. Later versions in wood and metal followed the same general contours as the natural horns.

In later centuries, man continued to refine trumpets, experimenting with the acoustical properties of such materials as silver, shell, horn, artificial tortoise shell, and most recently, plastic.

The hearing trumpets shown here all date from the Eighteenth and Nineteenth Centuries. In this period, it was common to fashion hearing trumpets from metal covered with vulcanite (hard rubber), or from brass, and them paint them black. In either case, it was hoped that the black finish would make the hearing trumpet less conspicuous against dark clothing worn by the user.

1-3 All three of these ear trumpets were used by Beethoven during various periods of his life. Numbers 1 and 2 are now in the Beethoven-Haus in Bonn. Number 3 was made for Beethoven by J.N. Mälzel (1772-1838), the inventor of the "Pan harmonicon", a mechanical instrument for which Beethoven wrote his Battle Symphony. Today, Mälzel is best known for his invention of the metronome. The ear trumpet he made for Beethoven may be seen at the Gesellschaft der Musikfreunde in Vienna.

4-6 These three ear trumpets are all of a type known as the London Dome, also sometimes called Grand Opera Dome. This type of ear trumpet was strongly resonant in the speech frequency. The exterior tube continues inside the dome, flaring out so that the mouth of the funnel faces the top of the dome. London Domes were made in many sizes, and the greater and individual's hearing loss, the larger sized instrument he was advised to use. Number 4 was made by the firm of Hawksley & Sons, London. The purpose of the lid on the bell end and the many large holes is not known, but the lid may have served to strengthen the thin metal and prevent bending and damage. Numbers 5 and 6 are a bell resonator style of London Dome that was made in polished brass and sterling silver. Both of these examples are ornately decorated with engravings and were manufactured by F.C. Rein & Son of England. They are now in the Amplivox hearing aid museum in London.

© 1976 Siemens Hearing Instruments, Inc. (FP1186-2500)

The one I made is based on an original owned by William McMillen dating from around the time of the Civil War.  Other originals can be found at http://www.civilwarantiqueshop.com/morepersonal.htm