Earbuds that Listen to the Heart

The human heart does more than beat, it vibrates. This hidden language of motion marks the precise opening and closing of valves, the subtle mechanics of life itself. Measuring these micro-cardiac movements requires specialized sensors placed directly on the chest, typically in a medical setting. Carnegie Mellon researchers have now shown that regular earbuds can be transformed into heart-vibration sensors that measure detailed heart valve activity with almost as much accuracy as chest-mounted medical devices.

The researchers repurposed the sensors already engineered into standard hearables by transforming the built-in speaker, the only transducer common to these devices, to act as an acoustic sensor that captures heart sounds at the ear. The system then uses these signals to reconstruct subtle seismocardiography (SCG) and gyrocardiography (GCG) waveforms to extract the timing of key micro-cardiac events.

The team will present their findings at the 2026 Association of Computing Machinery Conference on Human Factors in Computing Systems.

“Collecting these signals typically requires a clinical setting in which the patient lies down, removes their shirt, and is instrumented with accelerometers and gyroscopes,” says Justin Chan, assistant professor of electrical and computer engineering and computer science, and who advised the project. “Recordings are typically limited to a few minutes due to time constraints in busy clinics and patient discomfort during prolonged sessions. Our technology removes all of those obstacles and enables micro-cardiac monitoring at home. The secret sauce in our work is measuring the micro-cardiac rhythms with the built-in speaker. Every pair of hearables, from AirPods to Galaxy Buds, even to low-end earbuds you might get for free on an international flight and dispose of afterwards, has one thing in common: a speaker.”

While speakers normally push air to create sound, the team realized that by reversing the system, the same speaker can behave like a sensor and respond to tiny vibrations coming from the body, including those generated by the beating heart.

The team conducted an Institutional Review Board-approved feasibility study with 18 users, comparing their innovative earbud-based system to standard chest-mounted medical sensors. They found that heart vibrations propagate through the body in predictable ways and can be detected both at the chest and inside the ear. By leveraging this physical connection, the team developed a machine learning pipeline that reconstructs detailed cardiac motion signals from earbud recordings. The reconstructed signals closely match those captured by medical-grade chest sensors, achieving correlations between 0.88 and 0.95.

“We discovered this works across different people and across different earbud types,” says Siqi Zhang, an electrical and computer engineering Ph.D. student and lead author on the paper. “We’re able to sense heartbeats when users remount the earbuds or listen to music.”

Wearable technology has become increasingly popular in the last decade. While smart watches and rings can track how fast the heart beats, these transformed earphones point to something deeper.

“Instead of just measuring how fast your heart beats, it listens to how it beats,” says Zhang. “And that distinction matters. Mechanical timing abnormalities can precede more obvious symptoms. Subtle shifts in valve dynamics could signal disease progression long before a person feels shortness of breath.”

The team believes this technology could eventually help with passively monitoring heart conditions and atrial fibrillation, as well as detect valve disorders.

“Most people already own earphones and listen to music,” says Zhang. “Now we can also monitor heart health at the same time.”