Premature infants in neonatal intensive care units (NICUs) are exposed to high levels of noise from medical equipment and hospital activity, which can negatively affect their development. The American Academy of Pediatrics notes that sounds such as beeps and alarms in hospitals can reach 2,000 Hertz—four times higher than the 500 Hertz typically experienced by fetuses in the womb. Some devices inside incubators, like ventilators, emit even higher frequencies.
To address this issue, Sophie Ishiwari and Gabby Daltoso, recent graduates of Penn Engineering, developed the Sonura Beanie—a small hat designed for premature babies that blocks out high-frequency sounds and plays filtered audio messages from parents. The device ensures all played audio remains below the 500-Hertz threshold considered safe for infants. "Gabby and I spent a lot of time shadowing and talking to nurses, clinicians, and staff in the Intensive Care Nursery at HUP as well as parents to develop something that could make a true difference," said Ishiwari. "We received input from hundreds of people."
The beanie includes soft speakers sewn into ear flaps and connects to an app allowing parents to play heartbeats or recorded messages. As babies grow closer to full-term development, sound frequencies can be adjusted accordingly. The design also accommodates necessary medical wires and tubes.
A clinical trial involving 30 premature infants began at the Hospital of the University of Pennsylvania (HUP) in November 2025. During the study, babies wear the beanie three times daily while feeding; researchers will compare stress markers such as heart rate with and without use of the device. Results are expected by April.
Wendy A. Henderson from Penn Nursing is leading the clinical trial alongside other Penn Medicine professionals including Lori Christ (medical director), Jessica Lazzeri (clinical director), and Rosemary Polomano (professor). "The synergy of innovation, talent, and collaboration makes Penn an optimal environment for translating technological advancements into practice," said Henderson.
Nurses have long worked to reduce noise in NICUs but found it difficult to eliminate entirely. Michelle Ferrant noted her team was immediately interested when approached about testing the new device: "When Gabby and Sophie approached us about this project, we were immediately intrigued." Kyndall Hawkins added that initial skepticism faded after seeing a baby calm down upon hearing his mother's voice through the beanie: "But, after watching a fussy baby instantly calm down when hearing his mom’s voice played over the beanie, I was quickly won over."
Families participating in trials report positive experiences using recorded messages with their infants during hospital stays far from home. Pamela Collins described how playing songs in Portuguese for her son John helped maintain a connection despite distance: "It’s hard not being able to be with him constantly while he’s in the hospital," she said.
Ishiwari reflected on listening to these recordings: "I’ve been by myself listening to recordings of moms, dads, and relatives... expressing so much love in their messages." Daltoso added: "The beanie allows families to put energy and love into their messages at a particularly scary and unsure time..."
Next steps include seeking U.S. Food & Drug Administration approval for wider use; because it is considered low-risk as a medical device, FDA review is being fast-tracked with hopes for approval within twelve months.
Pamela Collins expressed gratitude for both the technology and those behind it: "The beanie allows me to still be John’s mom even when I can’t be by his side... Every hospital and every mother and baby needs them."
