What Makes a Sound Source Directional?

Introduction

We should know that the sound propagation of ordinary speakers is centered on the sound source and propagates in all directions. The sound pressure in each direction is different, and the directional sound technology of directional speakers is a technology that allows sound to propagate in a direction. The control and processing of the sound source can make the sound source transmit sound along a certain path to form a directional sound source, thereby achieving directional propagation of audible sound waves, similar to the beam emitted by a searchlight, forming a "sound column". When people stand within the range covered by the "sound column", they can clearly hear the sound. Outside the range, the sound pressure level will have a very obvious attenuation. If the distance is slightly further, the sound will not be heard. Compared with traditional sound sources, the directivity The propagation of sound sources has obvious directionality and propagation range. This is directional sound technology. Speakers that can use this technology to produce directional sound are also called directional speakers.

Table of contents

1. Principle of directional speakers

2. What are the advantages of directional speakers over traditional speakers?

3. Types of directional speakers

4. Directional speaker application

1. Principle of directional speakers

The principles of directional loudspeakers involve technologies such as ultrasound, phase control, and acoustic arrays, which work together to propagate and directional control sound.

1. Ultrasonic principle: Ultrasonic directional speakers use the special propagation properties of ultrasonic waves to achieve directional propagation of sound. It focuses the sound to the target area by converting the sound signal into an ultrasonic signal and taking advantage of the unique characteristics of ultrasonic waves. For example, ultrasonic waves exhibit strong directionality and refraction when propagating in the air. This technology allows sound to be directed without causing a large spread of sound in other areas.
2. Phase control principle: Phase control is to control the interference and superposition of sound waves by adjusting the phase of the sound signal, thereby forming a sound beam in a specified direction. By precisely controlling the phase of sound waves, sound waves can be superimposed and enhanced in specific directions, while superimposed and weakened or canceled out in other directions, thereby achieving directional propagation of sound.
3. Principle of acoustic array: Acoustic array directional speakers use an array composed of multiple speaker units to achieve directional propagation of sound by controlling the sound timing and vibration amplitude of each unit. This technology adjusts the sound emission time and amplitude of each speaker unit to form a specific sound field distribution in space, thereby achieving the directional propagation effect of sound.

2. What are the advantages of directional speakers over traditional speakers?

Directional speakers have the following advantages over ordinary speakers:

Precise sound localization:

Directional speakers can precisely focus sound in a specific direction or area, allowing listeners to hear the location of the sound source more clearly, thereby providing a better sound localization experience.

Reduce environmental interference:

Directional speakers can concentrate sound to specific areas and reduce the spread of sound in other areas, thereby reducing environmental interference and improving sound clarity and recognizability.

Energy saving and environmental protection:

Directional speakers can use energy more effectively to spread sound to the target area, reducing energy waste and contributing to energy saving and environmental protection.

Create a more private listening space:

In scenarios where sound isolation or privacy protection is required, directional speakers can accurately deliver sound to the ears of specific listeners without spreading to the surrounding environment, thereby creating a more private and focused listening space.

3. Types of directional speakers

Directional speakers are mainly divided into several types: ultrasonic directional speakers, sound beam formers and phased array speakers. Each type has its own unique working principle and application scenarios.

Ultrasonic directional speakers:

This type of directional speakers uses the propagation characteristics of ultrasonic waves to achieve directional propagation of sound. It converts sound signals into ultrasonic signals and takes advantage of the high-frequency characteristics and directionality of ultrasonic waves, so that the sound can be more accurately focused on a specific area or target. This technology is often used in application scenarios that require a high degree of directionality, such as audio positioning, wireless communications, medical ultrasound imaging, etc.

Sound beamformer:

Sound beamformer directional speakers use a special acoustic structure to form directional sound beams through phase control and sound wave superposition. By controlling the phase difference of the sound wave front, the sound waves superimpose each other in space to form a directional sound beam. Sound beamformers are usually used in situations where sound needs to be transmitted over long distances, such as outdoor broadcasts, performance venues, etc.

Phased array speakers:

Phased array speakers use an array of multiple speaker units to achieve directional propagation of sound by adjusting the phase and amplitude of each unit. This technology can achieve more flexible and precise sound directional control, allowing sound to form complex sound field distribution in space. Phased array speakers are often used in application scenarios that require sound dissemination, sound localization and noise elimination in complex environments, such as conference room audio systems, voice enhancement systems, etc.

4. Directional speaker application

Directional speakers are widely used in a variety of scenarios, including audio broadcasts, security alarms, navigation systems, hearing aids, virtual reality and augmented reality applications, and more. According to the difference of usage scenarios, it is divided into two application directions: indoor directional and outdoor.

Indoor applications:

1. Audio broadcast: In indoor venues such as exhibition halls, museums, and art galleries, directional speakers can be used to direct the commentator's voice to specific audiences, so that the audience can hear detailed introductions to the exhibits and enhance the visiting experience.
2. Navigation system: In indoor places such as shopping malls, airports, train stations, etc., directional speakers can be used to provide directional navigation services to convey information about building structures, important locations, etc. to visitors to improve visitors’ navigation efficiency.

Outdoor applications:

1. Security alarm: In outdoor places such as public squares, municipal buildings, and sports venues, directional speakers can be used to send alarm information to specific areas in emergencies, improving the efficiency and accuracy of alarms and helping evacuation and emergency response.
2. Music performances: In open-air concerts, outdoor performance venues, etc., directional speakers can be used to directionally transmit music sound to specific audience areas, providing a better music appreciation experience while reducing interference to the surrounding environment.
3. Outdoor tour guides: In tourist attractions, outdoor scenic spots, etc., directional speakers can be used to provide outdoor tour guide services to tourists. Through directional transmission of audio guides, tourists can more conveniently understand the history, culture and scenery of the scenic spots.

We have specially designed different kinds of directional loudspeakers for these two application directions, indoor directional loudspeakers and outdoor directional loudspeakers. If you have some other requirements, you can ask us to customize your directional speakers.

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Frequently Asked Questions

How do ultrasonic directional speakers achieve sound beam formation?

Ultrasonic directional speakers leverage the nonlinear interaction of ultrasonic waves in air—a phenomenon known as the parametric array effect. By modulating an audio signal onto an ultrasonic carrier (typically above 40 kHz), the system generates audible sound through self-demodulation during propagation. This process enables extremely narrow beamwidths and high directivity compared to traditional loudspeakers.

What is the difference between phased array and parametric array directional speakers?

Phased array directional speakers use multiple speaker elements with precise phase and amplitude control to steer sound waves through constructive and destructive interference. In contrast, parametric array speakers utilize high-frequency ultrasonic carriers to generate directional sound via nonlinear acoustic interaction. Phased arrays offer better control over beam steering angles, while parametric arrays excel in creating highly focused sound beams with minimal side lobes.

What are the limitations of directional speaker technology?

Directional speakers can face challenges such as limited frequency response, reduced sound pressure level at long distances, and sensitivity to environmental conditions like humidity and air turbulence. Additionally, parametric speakers may exhibit distortion due to nonlinear effects, requiring careful signal pre-processing and power management.

Can directional speakers be used for audio zoning in public environments?

Yes. Directional speakers are highly suitable for audio zoning applications, allowing different audio content to be delivered to adjacent areas without interference. This is particularly useful in museums, retail stores, or interactive exhibits, where targeted sound delivery enhances user experience while maintaining a quiet ambient environment elsewhere.

How do directional speakers integrate with modern AV(Audio-Visual) control systems?

Most commercial-grade directional speakers can be integrated into AV control networks via standard audio interfaces such as analog line-in, Dante, or AES/EBU. Some models support digital DSP tuning, IP-based control, and beam shaping adjustments via software, making them compatible with centralized audio distribution and automation systems.