In the realm of in-air acoustic imaging, the quest for high-quality, real-time imaging has been a persistent challenge. Traditional Delay-and-Sum (DAS) beamforming, while simple and computationally efficient, falls short in delivering the high dynamic range and spatial resolution required for many applications. Its high sidelobes and wide main lobe result in low contrast images, making it difficult to discern fine details. On the other hand, advanced adaptive methods that could potentially offer better performance are often dismissed due to their high computational cost and the single-snapshot constraint of real-time field operation.
A team of researchers, Wouter Jansen, Walter Daems, and Jan Steckel, have proposed a novel solution to this dilemma. They have developed and implemented higher-order non-linear beamforming methods using the Delay-Multiply-and-Sum (DMAS) technique, coupled with Coherence Factor weighting, specifically adapted for ultrasonic in-air microphone arrays. The DMAS technique, unlike DAS, multiplies the delayed signals before summing them, which helps in reducing sidelobes and improving the contrast of the image.
The researchers have also ensured that their method is computationally efficient, allowing for GPU-accelerated, real-time performance on embedded computing platforms. This is a significant achievement, as it makes the method practically applicable in real-world scenarios where real-time imaging is crucial.
The effectiveness of their proposed method was validated against the DAS baseline using both simulated and real-world acoustic data. The results were promising, with the DMAS method demonstrating significant improvements in image contrast. This establishes higher-order non-linear beamforming as a practical, high-performance solution for in-air acoustic imaging.
The implications of this research are far-reaching. In the music and audio industry, for instance, this technology could be used to create more accurate and detailed acoustic maps of concert halls and recording studios, helping engineers to optimize the sound quality. It could also be used in the development of advanced audio equipment, such as directional microphones and speakers, that can precisely focus sound in a specific direction.
In conclusion, the work of Jansen, Daems, and Steckel represents a significant step forward in the field of in-air acoustic imaging. Their innovative approach to beamforming offers a promising solution to the long-standing challenge of achieving high-quality, real-time imaging.
