Implementation of Active Noise Cancellation for Small Confined Spaces

Abstract

Noise cancellation has slowly become a necessity instead of luxury. This is due to the increasing levels of noise pollution in today’s society. Exposure to prolonged and excessive noise has resulted in serious health problems ranging from stress, poor concentration and fatigue from lack of sleep, to more serious issues such as cardiovascular disease, cognitive impairment, tinnitus and hearing loss. Such noise pollution levels are also harmful to fetuses as low frequencies are not attenuated in the same way as high frequencies are attenuated by the mother’s womb. Recent techniques such as noise cancelling headphones, earbuds are being implemented that provide noise cancellation limited to a single person and not to a small room as a whole. Thus our paper proposes a duct system, which will be using the concept of active noise cancellation with the application of digital adoptive feedforward control, where an anti-noise signal is generated, having same amplitude as that of the noise signal but of reverse phase which when added together will cancel each other out. The adaptive filter is controlled by a microphone located in the duct to sense the noise reduction and adjust the entire system for optimum operation. The noise cancelling headphones that are being in use nowadays also operate on the same principle that is being implemented by our proposed system. But due to complex designs in the circuits such devices usually end up being too costly. So our system aims at providing a low cost solution. The system is mainly aimed at lower range of frequencies up to 1 KHz. Active noise control is being preferred as passive silencers are bulky and the attenuations achieved for low frequencies are relatively small.