If the thought of going to the dentist makes your teeth chatter with fear, you're not alone. At least 15 to 20 percent of adults are believed to have odontophobia—aka dental anxiety—which prevents them from maintaining regular cleanings and dental check-ups.

One of the biggest sources of this anxiety comes from the high-pitched, eardrum-piercing sound of a dental drill used to cut into the teeth. 

"I repeatedly saw patients—including my own child—become anxious or uncomfortable with the sound of the dental drill," Dr. Tomomi Yamada, a dentist and professor at the University of Osaka in Japan, tells Popular Science. "At some point, I realized that someone needed to take this problem seriously."

Today, Yamada is presenting new research on how to reduce the noise in dental tools at the Sixth Joint Meeting of the Acoustical Society of America and Acoustical Society of Japan, in Honolulu, Hawaii.

"Because this challenge involves both human psychology and the mechanics of the device, I knew it could not be solved by dentistry alone," she says.

To better understand the aerodynamics of the drill, Yamada and her collaborators from the University of Osaka, Kobe University, and National Cheng Kung University used Japan's main supercomputer to conduct large-scale aeroacoustics simulations. They studied the internal and external airflow of the dental drill, which is powered by compressed air and rotates at roughly 320,000 revolutions per minute.

Using these computer simulations, the team visualized how air moves through and around the drill to create that signature unpleasant noise. They analyzed the airflow and also the sound pressure inside and outside the dental drill to pinpoint exactly where the noise is generated.

"The most surprising part was being able to visualize the ultra-fast airflow inside the dental drill, Yamada says. "Inside the turbine, the compressed air can reach speeds of about 135 meters per second?roughly Mach 0.4 [about 306 miles per hour]."

The simulations revealed that just making the drill quieter is not enough to make that sound less piercing. The sound quality must also be improved. To address this, the team is working on optimizing the blade geometry and exhaust port of the drill to minimize the noise, while maintaining its performance.

Additionally, Yamada and the team wanted to ensure that their research is "human-centered," and takes the patient experience into consideration. They tested the psychological effects of the dental drill's high-pitched sounds. Younger listeners have different reactions to the drill, perceiving its sounds as louder and more unpleasant. 

"If a child says the dental drill 'hurts' or 'sounds scary,' it's not just their imagination," Yamada says. "Children truly hear and perceive high-frequency sounds differently from adults—often louder and more unpleasant."

The team's next steps involve working with dental tool manufacturers to create working prototypes for testing. According to Yamada, completely eliminating the sound would not work for safety reasons, since the sound of the drill itself signals to patients that the instrument is active and helps them stay still.

They also plan to explore creating a more pleasant sound design that feels more calming and reassuring for patients.