Advanced Directional Audio System Using Optimized Ultrasound Technology with Environment Compensation

Abstract

This paper presents the design of an advanced directional audio system using ultrasonic modulation technology with environmental compensation. The system employs a DSP controller, ultrasonic transducer array, and power amplification stage to produce a highly directional sound beam. Temperature and humidity sensors are incorporated to compensate environmental variations affecting ultrasonic propagation. The proposed architecture improves sound clarity, beam directivity, and reduces distortion.

Introduction

Conventional audio systems spread sound in all directions, which can cause noise interference and lack of privacy in public environments. A unidirectional (directional) sound system solves this problem by focusing sound into a narrow beam so that only people within the beam can hear it clearly. This technology uses ultrasonic carrier waves (around 40 kHz) to transmit audio signals. The audible sound is modulated onto ultrasonic waves, and when these waves travel through air, nonlinear interactions demodulate the signal, reconstructing the original audio only along the direction of propagation.

The proposed system uses digital signal processing and a 7×7 ultrasonic transducer array to create a focused sound beam. The audio signal is first converted to digital form using an Analog-to-Digital Converter (ADC), processed and modulated with an ultrasonic carrier by a controller, then converted back to analog using a Digital-to-Analog Converter (DAC). After amplification through a high-power amplifier, the signal is transmitted through the ultrasonic transducer array, producing directional sound.

Previous research introduced the parametric acoustic array concept, which forms the basis of directional sound systems. Later developments improved sound focusing using transducer arrays and digital signal processing. However, challenges such as distortion, limited sound intensity, and power consumption still exist.

The system was implemented using hardware components including a LAUNCHXL-F2800157 DSP board, AD9280/AD9708 ADC-DAC modules, OPA541 power amplifier, and a 40 kHz ultrasonic transducer array. Experimental results showed that the system successfully produced highly focused sound, audible only within the target area while minimizing sound leakage.

Overall, the system demonstrates effective directional audio transmission and has potential applications in museums, targeted advertising, assistive listening devices, exhibitions, security systems, and personal audio zones, where private or localized sound delivery is required.

Conclusion

In this work, a unidirectional sound system based on ultrasonic directional audio technology was designed and implemented. The system utilizes ultrasonic carrier waves, digital signal processing, and an array of ultrasonic transducers to generate a highly focused sound beam. The audio signal is processed through ADC and DAC modules and modulated with an ultrasonic carrier before being amplified and transmitted through the transducer array. Due to the nonlinear properties of air, the ultrasonic signal undergoes self-demodulation, reproducing the audible sound only along the direction of the beam. Experimental results confirmed that the system can successfully deliver sound in a specific direction while minimizing disturbance to nearby areas. This directional property makes the system suitable for applications such as targeted advertising, museum exhibits, assistive listening systems, and private audio zones. Future improvements can focus on increasing transmission distance, improving sound clarity, and optimizing the transducer array design to further enhance the performance of the system.

References

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Copyright

Copyright © 2026 Prof. Hemambika V, Prof. Smitha Paulose, Aswin Syam, Anjana S, Nandana Krishna P B, Muhammad Midlaj A. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.