Looking Toward Cloaking & Acoustic Tagging: Researchers Implant 3D Printed Objects with Sound Data

For many, 3D printing has an aura of magic about it, allowing for objects to appear before your eyes as you summon them at will. And while the technology is used for numerous and expanding high-level projects, from the bioprinting of human organs to traveling in space, it offers enormous appeal for a growing volume of users of all ages around the world. Now, as researchers from Columbia Engineering, funded in part by the National Science Foundation and Adobe, work with MIT and Disney Research, the magic grows further. Especially with the idea that their latest work may one day actually even lead to the cloaking of objects and devices.

Centered around voxels, a number of which add up as values comprising a volume in 3D space, the research team has come up with a new concept and process that starts by controlling sound waves initially, but has the potential to go much further with incredible versatility, perhaps in retail, automotive, copyrighting, or even as far as the ocean. With acoustic filtering and tagging, the team led by Columbia Computer Science Professor Changxi Zheng is combining volume and 3D printing in a way most of us certainly never would have considered.

Here, 3D printed objects—of virtually any shape—can work as the vehicle for acoustic filters through specially designed voxels that make up one whole system, allowing sound to flow in and out. The voxels can be used to make any sized structure (think Legos) to fit inside any 3D print, and due to the properties of their ‘internal chambers,’ can modify the way sound data is filtered. Outlining their project in ‘Acoustic Voxels: Computational Optimization of Modular Acoustic Filters,’ the team will now present the concept at at SIGGRAPH 2016 in Anaheim, CA on July 27.

“In the past, people have explored computational design of specific products, like a certain type of muffler or a particular shape of trumpet,” says Zheng. “The general approach to manipulating sound waves has been to computationally design chamber shapes. Our algorithm enables new designs of noise mufflers, hearing aids, wind instruments, and more – we can now make them in any shape we want, even a 3D-printed toy hippopotamus that sounds like a trumpet.”

 

“We also have proposed a very intriguing new way to use acoustic filters: we can use our acoustic voxels as acoustic tags, unique to each piece we 3D print, and encode information in them. This is similar to QR codes or RFIDs, and opens the door to encoding product and copyright information in 3D printing.”

This is not the first time the team has dabbled in manipulating acoustics, as well as working to improve them—and it’s also not their first experience incorporating 3D printing and experiencing all of the resulting benefits therein. In 2015, we followed along as the researchers applied their computational technique in creating and 3D printing what they cleverly dubbed the zoolophone, a variation on the xylophone—and in that case, made with wooden keys in animal shapes. This was obviously a preliminary project in comparison to their latest, showing that they were becoming increasingly interested in sounds in relation to geometries, and manipulating them together.

The geometries grow significantly more complex and more varied as the researchers delve further into both acoustics and 3D technology.

“Using an efficient method of simulating the transmission matrix of an assembly built from these underlying primitives, our method is able to optimize both the arrangement and the parameters of the acoustic shape primitives in order to satisfy target acoustic properties of the filter,” state the researchers in their paper.

The team is making progress that could prove to be far-reaching, with items like car mufflers and musical wind instruments as examples of what could be substantially improved on.

“With 3D printers today, geometric complexity is no longer a barrier. Even complex shapes can be fabricated with very little effort,” Zheng notes. “So the question is: can we use complex shapes to improve acoustic properties of products?”

And while it’s certainly off the topic of manufacturing and copyrighting, it’s not too surprising to hear that their ambitions may travel as far as the sea too, incorporating control of ultrasonic waves.

“We are investigating some of the intriguing possibilities of ultrasonic manipulation, such as cloaking, where sound propagation can be distorted to hide objects from sound waves. This could lead to new designs of sonar systems or underwater communication systems. It’s an exciting area to explore.”

Looking into the details, it certainly seems as if they are doing more than improving. Perhaps exploring, innovating, and extending would all fit here too as they consider what acoustic tagging, as well as even cloaking, could do. With tagging, the team can basically implant acoustics in the 3D printed piece. Like a futuristic bar code, this allows for data to be kept inside the object and could be very useful for copyrighting as the structure of the voxels is completely unique to that object, and also holds its own signature. This is of course something that would transfer well to QR codes for example, allowing for manufacturers to build a fingerprint right into items being manufactured, with the rewards being a savings on the bottom line in production, as well as in time and effort.

As the researchers point out, while one object may look the same on the outside, it could have a completely different acoustic build within, producing a varied sound. They tested the idea with an iPhone app created specifically for this project, recording the sounds and then identifying each object correctly. This could also have great implications for stamping original 3D printed artwork as well as figurines, looking toward the embedding of acoustic data—which may work surprising magic all around as everyone from the artist to the retailer feels the benefits. How else do you think this concept might be useful? Discuss further over in the Acoustic Filters & 3D Printing forum at 3DPB.com.

[Source: Columbia Engineering / Images: Columbia Computer Science]