Researchers envision new kinds of noise cancellation headphones
ECE ILLINOIS PhD student Sheng Shen, W.J. "Jerry" Sanders III - Advanced Micro Devices, Inc. Scholar in Electrical and Computer Engineering Romit Roy Choudhury, and Assistant Professor Haitham Al-Hassanieh have developed a new technique at the Coordinated Science Lab to improve upon noise-canceling technology that could eventually make headphones “hollow”, as opposed to today’s bulky ear-blocking designs.
Current active noise-canceling headphones work by placing a microphone inside the ear cup to listen to ambient noise, and according to a report by the New Atlas, generates an anti-noise sound wave that is “opposite” in phase to the ambient sound. However, with this method, the headphones just have tens of microseconds to process sound, calculate an antinoise signal, and send it through the headphone speakers. This tight computing deadline sets an upper limit on the frequencies that it can actively cancel. Consequently, headphones are bulkier and there will be some ambient noise that gets past the headphones.
The researchers' technique focuses on the fact that wireless signals travel a million times faster than sound waves. By "placing the microphone closer to the source of the noise to be canceled and sending the soundwaves to the earpiece wirelessly, there is more time to generate a better anti-noise signal."
"The main hardware challenge is to get rid of any sound-absorbing material, and instead design a wireless forwarding system that runs very fast to provide the maximum 'head start' to the ear piece," says Shen.
"Our ear device gets the sound information in advance, and has much more time to produce a better anti-noise signal," says Roy Choudhury.
Shen and his colleagues were able to use embedded microphones out of the earpiece to create a noise-cancellation system they called MUTE. With physically separated components connected through a wireless network, the MUTE system is allowed more time to process incoming sound which translates to having a hundred times longer duration to execute the necessary noise-cancellation computations.
One practical application of this improved technology can be used for an office setting in which if somebody in their office wanted to cancel out the noise of their co-workers in the hallway outside, they could place an Internet of Things (IoT) microphone at the office door. Since this approach results in an improved anti-noise signal, the researchers claim that it is possible to attain a "comparable level of noise cancelations as headphones with ear-encompassing ear cups using only a behind-the-ear device that doesn't completely block the ear canal." Furthermore, it could be possible to even achieve stronger noise-canceling headphones by using this technology in a "conventional noise-canceling headphone form factor."
Regarding privacy concerns, Shen adds, “the most common privacy concern is that our IoT device will secretly record someone’s voice. In fact, It is designed without the capability to record the sound, because the moment the device hears the sound it is sent out wirelessly. The moment the device hears the sound, it is sent out wirelessly."
"This is bound to change the way we think of noise cancelation, where networks of IoT sensors coordinate to enable quieter and more comfortable environments," says Hassanieh, a co-author on the paper. Shen adds, "the moment the device hears the sound it is sent out wirelessly."
Their team presented this month last month at the Association for Computing Machinery Special Interest Group on Data Communication (ACM SIGCOMM) conference in Budapest, Hungary.