The thorax, located between the neck and abdomen, is key for assessing respiratory health through lung and larynx sound vibrations. Traditional evaluations are subjective, depending on examiner skill. Although multipoint electronic stethoscopes help detect breathing issues, technology for analyzing vocalization-induced vibrations is still underdeveloped.

In a study published in AIP Advances, French researchers showcased ultrasound’s effectiveness in detecting subtle chest surface movements caused by vocalizations. They also demonstrated the potential of the “airborne ultrasound surface motion camera” (AUSMC) to map these vibrations over short durations, illustrating their changes over time.

“AUSMC is a new imaging technology that allows the observation of the human thorax surface vibrations due to respiratory and cardiac activities at high frame rates of typically 1,000 images per second,” says author Mathieu Couade, PhD. “The technology shares the physical principle of conventional ultrasound Doppler imaging, but it does not require a probe to be applied on the skin.”

The researchers tested the AUSMC on 77 healthy volunteers to image the surface vibrations caused by natural vocalizations with the aim of reproducing the “vocal fremitus”—vocalization-induced vibrations on the surface of the body—as typically analyzed during physical examination of the thorax. Surface vibrations induced were detectable on all subjects, they reported.

“The spatial distribution of vibrational energy was found to be asymmetric to the benefit of the right size of the chest, and frequency dependent in the anteroposterior axis,” says Couade. “As expected, the frequency distribution of vocalization does not overlap between men and women, with the latter being higher.”

Ongoing clinical trials will use the AUSMC to focus on the identification of lung pathologies. But the researchers are hopeful that the technology, coupled with artificial intelligence algorithms, could usher in a new era of thorax examination in which vibration patterns can be isolated. This would offer a much better window on respiratory health and enable better diagnoses of respiratory diseases, they say.