Enhancing Audio Coverage and Minimizing Noise Pollution

12 min read

Learn how Holoplot audio technology utilizes revolutionary 3D beamforming to improve uniform coverage in public spaces, installations and conferences.

Enhancing Audio Coverage and Minimizing Noise Pollution
Enhancing Audio Coverage and Minimizing Noise Pollution

19/09/2019

Traditional loudspeaker technologies have been around for a long time, and while these have come a long way since their inception, they’re not without shortcomings. They are characterized by a loss of volume over distance, feedback and in many cases poor uniformity of coverage. Holoplot’s groundbreaking approach to public announcement (PA) system design represents a significant enhancement in sound reinforcement that helps acoustic consultants, sound designers, and event planners deliver ideal audio coverage to every seat in the house.

In this blog article, we will introduce the challenges of conventional loudspeaker systems and identify four ways in which the live sound reinforcement market benefits from Holoplot’s breakthroughs in wave field synthesis and 3D beamforming.

Coverage

In live sound, coverage is defined as the area that experiences a consistent audio response within a 6 dB drop-off from the sweet spot. From the perspective of sound design and acoustic performance, uniform coverage refers to a consistent listening experience from every position in the specified audience area. Acoustic consultants and sound designers take into account a number of variables to create uniform coverage, depending on the environment and application.

Room Acoustics

In order to achieve an optimum sonic experience for attendees, consistent sound pressure level (SPL) and frequency response need to be delivered across the entire audience area. For indoor venue situations, the room acoustics have a significant impact on audio quality, and in some instances require extensive acoustical treatment to minimize reflections and reverberation time. This often necessitates the use of multiple loudspeaker arrays to deliver clear audio signals to each listening position in the audience.

Speech Intelligibility

In applications where the sound system is primarily used to amplify speech, the system’s capability to produce a signal with an appropriate direct-to-reverberant ratio is crucial. This becomes particularly challenging in buildings where walls and ceilings consist of hard and smooth surfaces like concrete, drywall, and glass. Whereas softer materials generally absorb sound and yield greater clarity, these harder materials reflect sound waves and increase reverberation time, making it more difficult to deliver high levels of speech intelligibility.

Uniform Coverage

A primary limitation of conventional loudspeaker design is a lack of uniform coverage, resulting in inconsistent listening experiences for audience members throughout different parts of the room. This failure is caused by the inability to fully control the signal directivity of conventional column and line array speakers, creating a loss of sound pressure level over distance. The reason for this attenuation is that, in the horizontal plane, a line array still acts like a point source – its directivity can only be shaped in the vertical plane with splaying or digital signal processing.

4 Ways Holoplot Improves Coverage with 3D Beamforming

Where conventional sound systems drop the ball, Holoplot’s 3D beamforming technology helps audio professionals deliver uniform coverage in a variety of methods – by delivering consistent sound pressure levels over long distances, decreasing noise pollution in unwanted areas, and increasing speech intelligibility in reverberant environments. Last but not least, Holoplot technology makes it possible to create multiple targeted sound zones for public announcements and creative installations.

Enhancing Direct-to-Reverberation Ratio with Equal Levels Over Long Distances

Based on the principles of wave field synthesis, Holoplot technology has introduced 3D beamforming, a new tool for improving the ratio of direct sound to reverberation. In practice, this means that waveforms can be shaped and steered vertically, horizontally and diagonally. These steering capabilities allows system engineers to create spherical beams, planar beams and focus beams.

Planar beams are highly energy-efficient sound waves that only attenuate with air resistance. This results in a high concentration of sound pressure over long distances. Within the coverage area of the beam, the SPL is nearly constant, and only drops outside the area. With beamforming, acoustic designers and system engineers can minimize reflections off hard surfaces, leading to significantly improved direct-to-reverberation ratios and reduced impact from the diffuse field.

With Holoplot technology, a single centralized PA system can cover great distances with uniform levels and high intelligibility. A test installation with Germany’s Deutsche Bahn train station demonstrated sound pressure level losses of only 5% over a distance of 325 feet (100 meters). Conventional sound systems would require multiple loudspeaker arrays in different positions to achieve uniform level distribution over such a distance.

For live music applications, Holoplot 3D beamforming technology can be used to cover the entire audience area with uniform SPL and frequency response using a single loudspeaker array position, without the need for multiple arrays and delay towers.

Decreased Noise Pollution in Non-Targeted Areas

When planning a sound system for railway stations, conferences or concerts, it is important to minimize noise pollution beyond the desired area of coverage. Planar beams are extremely useful for avoiding unwanted noise pollution. They concentrate the sound energy in areas it is needed, adding very little to the diffuse field.

Another beam type that Holoplot technology enables is the focus beam. With its spherical shape that has a 30cm diameter, a focus beam makes it possible to precisely focus an audio signal into a specific location in space. This greatly reduces noise pollution while creating a feeling of proximity to the source for the listener.

The ability to control the type and direction of sound waves makes it possible to freely steer sound energy. This can reduce the noise pollution outside the desired coverage area.

Increased Speech Intelligibility in Reverberant Environments

Signal clarity and intelligibility are crucial in both music and speech-focused applications for a wide range of reasons, including safety, comprehension, and emotional impact. Especially in reverberant environments, hard surfaces cause reflections and echoes, making it harder to clearly understand the vowels and syllables of speech.

Holoplot 3D beamforming technology helps to overcome these challenges by focusing sound energy only where the audience is, while avoiding surfaces that contribute to reverberation. This greatly improves speech intelligibility in otherwise reverberant spaces, so that the message is heard loud and clear by every audience member.

Isolated Sound Fields in Public or Creative Applications

In many creative sound installations, it is sometimes desirable for different content to be audible in different zones of the listening space. This can be quite the challenge due to the fixed directivity and noise pollution caused by traditional speaker systems.

Holoplot technology provides new possibilities in the design of targeted sound zones. Using 3D beamforming, a single system can be configured to steer multiple discrete signals individually to different targeted areas, enabling impressive isolation of unique content within each zone.

New Horizons

The limitations of conventional loudspeaker technologies create a host of challenges for designers of public spaces, content creators and sound engineers, and ultimately, audiences themselves. By approaching the underlying physics of acoustic design in an innovative way, Holoplot wave field synthesis technology enables system designers and audio professionals to overcome these challenges and reimagine new possibilities in audio coverage.

 

To learn more about Holoplot audio reinforcement systems for conferences and speech-based applications, get in touch or contact info@holoplot.com