In the hushed corridors of the International Space Station (ISS), where human voices float as weightlessly as the bodies that carry them, Indian astronaut Shubhanshu Shukla and his Ax-4 crewmates are helping decode the science of sound in space — quite literally.The Ax-4 crew recently lent their voices to the “Voice in Space” study, a pioneering experiment investigating how microgravity alters human speech. Without gravity’s usual pull on the lungs, diaphragm, and vocal tract, even subtle changes in vocal fold vibration or tone can occur. Using electroglottography — a non-invasive technique used to measure vocal fold contact during voice production — sensors and a series of scripted vocal tasks, researchers are capturing these shifts to understand how spaceflight affects speech patterns and cognition. Training AI on EarthThe aim? To train artificial intelligence systems that can one day monitor astronaut health in real time — and perhaps even enhance voice-based AI technologies back on Earth. This study blends physiology, acoustics, and machine learning. “This experiment seeks to determine whether the influenced voice pattern and listening capabilities of the participant might be able to be detected by an AI algorithm. Vocal characteristics of an ISS crew member can change in a zero-gravity, and after undergoing cognitive function changes. Measurements of vocal fold vibration provide a quantitative indication of vocal fold function,” as per Axiom Space.Scripted voice audio recordings — reading, singing, vowel enunciation, audio pitch matching— allow for tonal analysis, Axiom said, adding that these data allow the investigator to test and analyse vocal performance and voice pattern changes in space and then evaluate how space journey influences the human voice.UltraSound & fabric studyBut sound wasn’t the only thing on the crew’s mind. Alongside the voice study, they completed multiple sessions of the “Cerebral Hemodynamics” investigation — an exploration into how blood flows through the brain in a zero-gravity environment. Without gravity pulling fluids downward, astronauts often experience a fluid shift towards the head. By using ultrasound to monitor these changes, scientists hope to develop better diagnostic tools for cardiovascular and neurological conditions — tools that could serve both astronauts and patients on Earth suffering from stroke, dizziness, or fainting.Also on the roster of the Ax-4 crew is the “Suit Fabric Study”, a technology demonstration examining how clothing behaves in space. This isn’t just about comfort — it’s about performance. The crew wore sensor-equipped garments during exercise to observe how heat and moisture are managed when convection is no longer at play. “The findings could inform the design of next-generation space suits — and inspire innovations in thermal wear on Earth, from sports gear to medical textiles,” Axiom added.