Hearing things? That noise just might be your clothes. From shirts that detect heartbeats to hats that alert oncoming traffic that someone is in the road ahead, fabric clothing may someday do double duty as a communication system.
Massachusetts Institute of Technology engineers and folks at the Rhode Island School of Design (RISD) are working together on an “acoustic fabric.” (Acoustic means related to noise or hearing.) The fabric contains ultra-thin fibers that undulate in response to sound waves, similar to seaweed in water or hair cells (stereocilia) in the human ear’s cochlea.
God designed ears so that they pick up tiny vibrations. The brain interprets these movements as sounds. Taking cues from the human ear, the team sought to create a fabric “ear.”
Researchers invented a bendable fiber and wove it into ordinary fabric. The fiber allows the fabric to detect sound vibrations and convert them to electrical signals.
“It feels almost like a lightweight jacket—lighter than denim, but heavier than a dress shirt,” says RISD graduate student (class of 2022) and acoustic fabric weaver Elizabeth Meiklejohn.
Researcher Wei Yan helped develop the fibers. He sees many communication uses for acoustic fabrics.
The fibers can sense both soft and loud sounds—including a wearer’s heartbeat. Amazingly, the fibers can also be engineered to make sound and sense the direction a sound is coming from.
Scientists imagine that a directional sound-sensing fabric could help those with hearing loss tune in to the right sounds even in noisy settings.
“You might talk through it to answer phone calls,” says Yan. The fibers could also allow “wearers to monitor their heart and respiratory condition[s].”
To test the heartbeat notion, the team sewed one fiber into a shirt, right over a test subject’s chest. The fiber correctly sensed the heartbeat. And here’s the kicker: The fiber also detected subtle changes in the heart’s normal sounds.
One of Yan’s co-authors, MIT Professor Yoel Fink, sees possibilities for helping monitor a baby’s fetal heartbeat by putting the fiber into maternity clothing.
“The fiber is opening widespread opportunities,” Yan says.
Some go beyond helping humans. “It can be . . . embedded into buildings to detect cracks or strains . . . or woven into a smart net to monitor fish in the ocean.”
The uses for acoustic fabrics seem myriad. Someday, turning up a hearing aid, answering the phone, or monitoring one’s health could be as easy as changing your shirt.
Why? The human ear is an amazing feat of engineering and is still a source of inspiration for scientists doing cutting-edge research.