A horn or a horn loudspeaker is part of a siren which provides direct transmission of an audio signal into the air. In general, the type of horn that is used in a siren/warning system directly affects the quantity and quality of acoustic coverage, flexibility and convenience of the system installation in a variety of projects and climatic conditions, as well as the required frequency of the siren/system maintenance and inspection. The most important aspects to be considered in the design of outdoor warning systems are described below.

Firstly, it is important that horns perform their main role, which is to provide the maximum sound coverage and ensure the high quality of sound transmission. It is worth noting that a sound emission pattern is of great importance as well because the territory that needs to be alarmed is not always circular or oval. Also, there may be areas with high levels of background noise or perhaps zones where obstacles to sound transmission occur. In all these cases, it is necessary to redistribute the sound emitted from the siren so that there are no blind spots in the acoustic coverage.

Secondly, it is important to consider the material a horn is made of. This also has an impact on the sound quality. However, the most influential factors are its robustness and resistance because the horn is always installed outdoors and exposed to adverse environmental effects. Moreover, early warning systems are often designed for countries with extreme climatic conditions.

The convenience of installation plays another role as there is sometimes no opportunity to mount horns on a regular pole. They are frequently installed in close proximity to walls, slightly tilting downwards, or in other non-standard locations (windy areas, vehicles, etc.). It should be mentioned that different sizes of horns may be needed in such cases. For example, in areas with high winds, or in sirens mounted on vehicles, smaller dimensions of horns to reduce aerodynamic resistance are recommended.

Regarding horns, the Telegrafia company tackled the issue of designing the horn for outdoor sirens very carefully. It tested different shapes and materials until the final decision was made to produce horns with unidirectional, bidirectional and omnidirectional characteristics (small and large in size, made of durable and lightweight aluminum alloy) that fully meet all the above requirements. Our company has been using this type of horns in sirens for more than 20 years. They have been tested in all possible climatic conditions and stood the test of time; therefore, they are absolutely ideal for all outdoor early warning systems.