In the sphere of audio technology, probably no part brought as great a contribution to the development and is rooted as deeply as the loudspeaker horn. For over a century, this rather simple yet ingenious device has been at the basis of sound reproduction remaining relevant in a multitude of applications from the simplest public address system to the highest fidelity home audio entertainment systems.
In its simplest form, a loudspeaker horn is therefore an acoustic transformer. It functions as a waveguide that provides directivity and matches the displacement of a complex driver to the air effectively, thereby raising the sensitivity. I will explain in words what can be visually observed in the real horn: the basic principle of its operation is utterly simple, but its impact on the mechanisms of sound reproduction is staggering.
History
Therefore, it is possible to state that the horns of the loudspeakers are very old from the point of view of the history of sound reproduction. In the period before the development of electronic amplifiers in both record players and radio sets at the end of the late nineteenth and early twentieth centuries, horns were vital in increasing the loudness of music played on phonographs and received through early radio sets.
These early horns were also big in size and were quite cumbersome but they did the job needed, that was to amplify sound for it to pass over rooms or even outside.
That is why, when electronic amplification decided to take a larger part of people’s lives, the role of horns changed. Instead of being a requirement that would make the sound louder just to be heard, they became valuable for their efficiency and the fact that they could transmit sound over very vast distances. This made them particularly useful in the PA systems, theaters, and subsequently, in large concert sound reinforcement applications.
Loudspeaker horn design has more to do with acoustics and geometry details than with simple horn design. This is usually in the conical form but other higher horn shapes include exponential, hyperbolic, and tractrix horns. Each of these shapes contains a different characteristic of acoustics; low-frequency cutoff, throat impedance, and directivity control.
That is why one of the primary benefits of horns-loaded speakers is the possibility to increase their efficiency. A loudspeaker horn, thus, can create higher SPL with reduced input power compared to a direct radiator because it couples the driver to air efficiently. This efficiency was particularly great in the early times of amplification since powerful amplifiers were not easy to come by.
However, horn-loaded speakers also entail some advantages such as control of directivity. To accomplish this function, horns are utilized together with the speaker to help direct the energy of the wave in specific directions.
Modern Use
Horn speakers have the advantage of moderate directivity in practical use because they are controlled directly. In large facilities, it gives the capacity to direct sound to the coverage zone while dampening reflections from walls and ceilings. This can enhance the IDS by a very large margin in the case of the reverberant type, as shown in the equation below.
Horn speakers can work outdoors without much spillover to other surrounding areas and hence can be used in public address systems and in events that are held in open areas. You can click here to learn more about how they work.
With horn speakers comes the issue of size, more specifically, the large size of these horns for low ranges. To couple low frequencies to air, horns must be larger in size. As for the size requirement, it has been a major drawback in the application of full-range horn speakers in home audio. But with an increase in technology that has enhanced the horn manufacturers, their design has been made more compact to suit home use.
In many of the professional applications, the horn-loaded speaker systems continue to be popular. The main reproduced audio systems for concerts and events involve compression drivers and horns for high and mid-range elements, and direct radiator or horn-loaded subwoofers for lows. This results in a system that can produce a high output, possess optimized directivity and possess extension low and high frequencies.
The cinema industry has also been a prominent customer in the use of horn speakers. There is invariably a demand for high output levels and low directivity in large areas to affect more people in this case large theaters making horn-loaded subwoofers a perfect match. Some of the cinema speaker systems incorporate the use of several horns where each horn caters to a certain frequency response and the coverage plot.
Horn speaker technology has bright prospects in the future. This has given way to present research on new horn materials and horn manufacturing technologies like 3D printing technology. Such developments can result in considerable improvements by designing horn speakers that are small but very efficient for a whole host of uses.
Furthermore, the application of digital signal processing (DSP) together with the horn speaker systems is making it possible to control directivity as well as frequency response even more. This harmony of the old acoustic principles blended with the new age digital technology can be seen as a new and exciting area of loudspeaker development.
Thus, still unwavering in the importance of the art of audio reproduction, the loudspeaker horn awaits the next chapter in its development.
Regardless of the need to output sound over a large concert hall, speak clearly in a movie theater, or accurately reproduce the subtle characteristics of a symphony, deep in the comfort of one’s home listening room, the single loudspeaker horn continues to prove its relevance coherently and effectively.
With the growth of new technologies and the knowledge of operating with sound waves improving in the future, there will be other developments made with the horn, maybe introducing new uses for it and utilizing it in existing areas.
