Bugle megaphones were used on military garrisons to help amplify the sound of the bugle. Used in a garrison environment, the megaphone was mounted to a swivel on a post enabling the bugler to play in any direction and the sound to carry further and over a broader area. These pedestals were usually placed near the main flagpole or at garrison headquarters.
A megaphone is usually a portable or hand-held, cone-shaped acoustic horn used to amplify a person’s voice or other sounds and direct it in a given direction. The sound is introduced into the narrow end of the megaphone, by holding it up to the face and speaking into it, and the sound waves radiate out the wide end.
A megaphone increases the volume of sound by increasing the acoustic impedance seen by the vocal cords, matching the impedance of the vocal cords to the air, so that more sound power is radiated. It also serves to direct the sound waves in the direction the horn is pointing. It somewhat distorts the sound of the voice because the frequency response of the megaphone is greater at higher sound frequencies.
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