Opening windows for ventilation is not always an option, particularly when the disruption of outdoor noise overtakes the benefits of fresh air. Now, however, a recently published proof-of-principle study shows validation for an innovative device that reduces environmental noise coming through an open window and may bring relief to homes and offices in noisy urban environments.

Source: NTU SingaporeThe device, developed in 2018, fits into a two-panel sliding window and, according to the study, can reduce the perceived volume of noises from urban transportation by as much as 10 decibels or up to half. Created by Bhan Lam, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, and colleagues, the device consists of 24 loudspeakers (each 4.5 cm in diameter) attached to the inside of the window in a grid pattern with a sensor outside the window. When the sensor detects outside noise, the loudspeakers emit "anti-noise." The anti-noise is the same frequency as the noise detected by the sensor but has inverted sound waves that cancel out the sound and lower the volume of noise pollution entering the room through the open window.

The study authors placed the device in a replica room and played traffic, train and aircraft noises from a loudspeaker located 2 m away. Eighteen microphones inside the room detected the sounds before the noise control device was activated and the authors observed as much as a 10 dB noise reduction for sounds with a frequency above 300 Hz, which includes traffic and train noises.

The success of the study brings hope that this device can improve people's health by reducing noise pollution without compromising ventilation.

The study appears in Scientific Reports.