Horn speakers are a type of loudspeaker that uses a horn-shaped structure to increase the efficiency and directivity of sound. The acoustic principles behind horn speakers are based on the fact that as sound waves move through a horn, the horn's shape causes the waves to be compressed and focused, resulting in a more powerful and directional sound.

There are two main types of horn speakers: compression horns and exponential horns. Compression horns use a small driver that is mounted to the throat of the horn, which then expands out into a larger mouth. The driver creates high-pressure sound waves that are amplified by the horn's shape, resulting in a very efficient and loud sound.

Exponential horns, on the other hand, use a driver that is mounted at the mouth of the horn, which then tapers down to a smaller throat. This shape causes the sound waves to gradually expand, resulting in a smoother and more natural sound.

One important aspect of horn design is the flare rate, which is the rate at which the horn expands from the throat to the mouth. A slower flare rate will result in a more focused sound with a narrower dispersion pattern, while a faster flare rate will result in a wider dispersion pattern with less directionality.

Overall, the use of a horn in a speaker design can significantly improve the efficiency and directivity of sound, making it a popular choice for applications such as public address systems, concert sound reinforcement, and even high-end home audio systems.