Utilizing Sound Waves for Enhanced Public Safety

WASHINGTON, November 14, 2023 – The risk of hearing loss doesn’t just come from loud machines or other obvious noise. It can also affect people in public settings such as theaters and concert halls. Absorbing this excess noise to make public environments safer for hearing and using the unwanted sound waves to generate electricity is the goal of a paper published this week in Physics of Fluids, by AIP Publishing.

“According to the Centers for Disease Control and Prevention, an estimated 12.5% ​​of children and adolescents ages 6 to 19 and 17% of adults ages 20 to 69 have permanent hearing damage from excessive noise exposure,” says Rajendra. said Prasad P. “Noise above 70 decibels for extended periods of time can start to damage our hearing. We need systems that can really dampen large sounds.”

In their research, the authors focused on enclosed spaces such as theaters and concert halls and built a system of piezoelectric sensors that can be installed in the walls, floors and ceilings to absorb sound waves and collect their energy. Sound waves from speakers in these confined spaces are usually between 60 and 100 decibels, sometimes reaching 120 decibels, Prasad said.

“We classified the noise in closed environments based on the intensity (decibels) that can potentially cause hearing loss,” Prasad said. “Sound energy absorbed using piezoelectric sensors is processed by our system to convert it into electrical energy. Based on the energy generation pattern, the system’s output is switched between battery and direct bundled output.”

To design an optimal system for capturing sound waves in confined spaces, the authors used computer simulations to fine-tune variables including the voltage required to power the main device, the frequency and intensity of the input sound, and piezoelectric sensors tested in parallel and serial configurations.

“The surprising fact is that the design’s output is maximum around certain frequencies that match the frequency and intensity of the sound used in theaters or auditoriums,” Prasad said. “Our design reduces the vibration of sound each time it reflects off the piezoelectric material and reduces the overall sound intensity of the enclosed space.”

In addition to reducing the risk of hearing loss, the authors wanted to design an energy system that is good for the environment, using a smart energy management function that adapts depending on the amount of sound coming in. Environmentally friendly materials are also used.

“The piezoelectric material we used is a form of quartz, which is nothing more than a mineral composed of silica,” Prasad said. “It is easily biodegradable and also recyclable.”