Over the years, the technology in loudspeakers has evolved greatly, especially in the area of creating speaker cabinets which allow for the sound to be thrown over increasingly large distances.
Before getting into the detail of what makes line array loudspeakers clever, we need to start by explaining the difference between them and conventional loudspeakers, plus some handy terminology.
Conventional speakers have been around for years, with the first loudspeaker appearing in 1876, which was patented by Alexander Graham Bell, who invented it for intelligible speech for use in the first telephones. They come in many different shapes and sizes but are most commonly used for band PA systems or are installed for background music in venues such as restaurants, bars and nightclubs.
The size of a loudspeaker depends on the size of the driver. This driver is not the sort who will chauffeur you to a dinner party, but a crucial element of a speaker. It is often also referred to as a loudspeaker cone.
Sound from conventional speakers tends to spread out in a wide pattern, resulting in uneven coverage and potential sound reflections and interference. Often, speakers have a 90 x 90 dispersion, which means that the sound travels 90 degrees vertically and 90 degrees horizontally from the front of the speaker. This is fine in many locations, but for churches and large, reverberant spaces, this hinders sound quality and speech intelligibility.
So dispersion is how wide or narrow the sound radiates from a loudspeaker. The narrower the dispersion, the more controlled the sound from the speaker is going to be.
The primary advantage of line array speakers over conventional ones lies in their ability to control sound dispersion. These utilise a technique called vertical line array wavefront shaping to achieve a controlled dispersion pattern. That’s quite a mouthful, so what does it mean?
Simply put, the drivers in the speaker are precisely arranged in a vertical line within the cabinet, and each one is carefully angled so that when sound waves are emitted from the driver, the sound waves sum together to push the sound further out from the speaker and in a more directional manner.
Some (very expensive) line array loudspeakers, both in the installed and live performance markets, allow you to change the directivity of each speaker, which gives the sound engineer incredible control over the dispersion of sound. This is useful in particularly reverberant spaces such as a cathedral, where the speakers can be tuned to focus on the audience with the accuracy of a laser beam, maximising the coverage across the congregation and minimising issues caused by the sound reflecting off the large space.
Overall, the controlled dispersion of line arrays helps to minimise echoes and reflections, leading to improved speech intelligibility, especially in acoustically challenging environments. However, it is important to note that while line array speakers excel in certain applications, they may not always be the best choice for smaller venues or situations where precise control over sound dispersion is not a priority.