A powerhorn is a kind of loudspeaker with a funnel cone shape that can be used as a hand-held device or as part of a Public Address (PA) system. It is often used for sporting events, political functions, school events or for any activity with a need to amplify sound. A power horn can be acoustic or electric; an acoustic horn uses its funnel shape to project sound, while an electric horn uses battery or electric power to amplify and project sound.
When hand-held, a powerhorn is typically referred to as a bullhorn or a megaphone. The user speaks into the cone, whereby the sound of his or her voice is amplified as it travels through the funnel. The cone shape amplifies the voice by streamlining it in a specific direction, much like what happens when someone cups his or her hand around their mouth while speaking. Without the use of a bullhorn, the human voice cannot project as far, because the sound waves dissipate faster as they spread out in multiple directions. This amplification effect can be achieved both by an acoustic and electric powerhorn.
An electric hand-held powerhorn is battery-operated and typically features a vertical handle with a trigger-like mechanism that toggles the bullhorn from off to on. These work with the same audio science as do acoustic bullhorns, only they use amplifiers and microphones to increase the sound emitted from the speaker. Hand-held bullhorns can often be seen being used by cheerleaders and fans at sporting events as well as by political protesters during rallies.
Powerhorns in PA systems can generally be seen at sporting events as well as in school hallways and cafeterias. These employ the same funnel cone shape as a hand-held powerhorn, but are integrated into a speaker system able to transmit sound through multiple powerhorns in a building or general area. These emit sounds to signal an event to the listener—the end of class or approaching severe weather, for instance—as well as deliver a speaker's message to a larger audience than a single amplifier could reach.
As a result of their portability and simple application, powerhorns can be retrofitted as an accessory on cars and many other objects, and can be adapted for use in a variety of different situations. For example, many people use powerhorn sirens as a part of their home- or business-alarm system. The powerhorn's simple design allows it to withstand inclement weather conditions, making them ideally suited to outdoor and indoor purposes.