Latest news with #acoustics
The Independent
5 days ago
- General
- The Independent
Scientists finally crack mystery of how clapping generates sound
Scientists have finally unravelled the complex process that generates sound during handclaps, a discovery that shows how even simple acts can be rich with physics. The research, published in the journal Physical Review Research, shows that the characteristic ' pop ' sound of a clap is not just from two hands smashing into each other but a much more complex phenomenon. The key to generating sound from clapping is a cavity of air that is compressed and pushed out of a small space. Scientists followed an interdisciplinary approach to understand clapping, using live experiments, theoretical modelling and silicone replicas of human hands. They modified the volume and duration of claps by changing the speed, the shape of the hands and even the skin softness. 'We clap all the time but we haven't thought deeply about it. That's the point of the study,' said study co-author Yicong Fu from Cornell University, 'to explain the world with deeper knowledge and understanding.' 'The point was not to look just at the acoustics, or the flow excitation or the collision dynamics, but to look at them all simultaneously,' Likun Zhang, another study author from the University of Mississippi, said. 'That's an interdisciplinary effort that allows us to really understand how sound relates to hand clapping.' The study shows that when hands come together during a clap, they create a pocket of air between the palms. This pocket is rapidly expelled from the narrow opening between the forefinger and thumb, causing the air molecules to vibrate. Scientists liken this vibration to the Helmholtz resonance principle, which is behind the tone heard when blowing across the mouth of an empty bottle. 'Traditional Helmholtz resonators have rigid walls like the glass walls of a bottle. This produces a long-lasting sound that attenuates very slowly because most of the energy contributes to the acoustic signal,' Dr Zhang explained. 'But when we have elastic walls – let's say our hands – there is going to be more vibration of the solid material, and all of that motion absorbs energy away from the sound.' This is why clapping generates a single short 'pop' as opposed to a longer noise, researchers say. Scientists hope their research can help inform music education, where handclaps are often used for rhythm timing. The study also shows that every person's clap has a different sound and a different frequency, indicating that clapping can be used in the future as an identification method, like how we use fingerprints. 'One of the most promising applications of this research is human identification. Just through the sound, we could tell who made it,' Guoqin Liu, another author of the study, said.
Yahoo
22-05-2025
- General
- Yahoo
Scientist reconstructs sounds of ancient underground city with 3D virtual soundscape
Modern cities teem with diverse sounds, from the roar of vehicles to the melodies of music, and everything in between. Ever wondered what an ancient city sounded like? What whispers, daily routines, and echoes filled its very air? Sezin Nas, a researcher in interior architecture and acoustics at Istanbul Galata University, is exploring the soundscape of Derinkuyu, an ancient underground city in Turkey. The ancient engineers of Derinkuyu demonstrated incredible skill and foresight, constructing a city that was a masterwork of defense and self-sufficiency. Its primary purpose was defense against invaders, providing a secure refuge. Beyond military protection, Derinkuyu also offered a sanctuary from the harsh weather conditions prevalent on the surface. At times, it was even utilized to protect agricultural yields from natural calamities. At its zenith, Derinkuyu was a bustling underground hub, capable of accommodating as many as 20,000 people. Derinkuyu's vast population resided across seven interconnected underground levels, each designed for specific purposes. Crucial to the city's functionality was an intricate network of ventilation channels, vital for air circulation and remarkably, also used for communication. As Sezin Nas points out, there's a significant gap in our understanding of the acoustic environments of underground cities. Her research aims to fill that void. 'The integration of ventilation and communication functions within the same architectural elements is considered one of Derinkuyu's most unique features,' Nas said. 'This multifunctional use of the ventilation system strongly highlights the exceptional construction process of the site and plays a central role in shaping its soundscape.' BBC reported that Elengubu, now Derinkuyu, is the world's largest excavated underground city. It burrows over 85m deep, and consists of 18 levels of tunnels. Used almost continuously for millennia by various civilizations, including Phrygians, Persians, and Byzantine Christians, it was finally abandoned by Cappadocian Greeks in the 1920s during the Greco-Turkish War. To recreate the ancient auditory world of Derinkuyu, the researcher looked into the city's history and its architecture. She focused her analysis on three distinct spaces: a church, a living area, and a kitchen — considering room functions, sound sources, and reverberations to create a truly immersive 3D virtual soundscape. 'Derinkuyu underground city is considered an interior environment on an urban scale, which distinguishes it from the open-space urban soundscapes,' Nas said. 'Listening to the reconstructed soundscape provides insights into how sound influenced spatial experience, communication practices, and social organization within the underground city,' Nas explained. Nas envisions a dual impact for her research on Derinkuyu's soundscape. First, she believes the ancient city's unique acoustic environment can serve as a source of inspiration for the design of future underground urban developments. Beyond this practical application, Nas holds a broader ambition: she hopes that soundscapes, in general, will evolve into systematic tools for historical study. 'This research also highlights the role of historical sound environments as an important and often overlooked component of cultural heritage,' Nas said. Nas presented her research on the soundscape of Derinkuyu on Wednesday, May 21st. This presentation was part of the joint 188th Meeting of the Acoustical Society of America and 25th International Congress on Acoustics, an event that ran from May 18th to May 23rd.
