Active noise cancellation through adaptive filtering

• Grant number: 06/00860-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2006
• End date: December 31, 2006
• Field of knowledge: Engineering - Electrical Engineering - Industrial Electronics, Electronic Systems and Controls
• Principal Investigator: Vitor Heloiz Nascimento
• Grantee: Ewerton Ickowzcy
• Host Institution: Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Traditional methods for noise control are based on sound-absorbing materials. Since they are based on bulky materials, these so-called passive methods are not adequate for low frequencies, whereas good performance may be obtained for frequencies below 500Hz with active noise control methods. Active noise control works by cancelling an undesired primary noise with another noise in opposition of phase. Most active noise control systems employed in headphones use fixed analog controlers, with feedback. However, changes in the environment, in the headphone positioning, and ageing of components, may limit the best possible system performance. Adaptive filters could be used to track these time variations, but digital adaptive filters will in general introduce too much delay in the feedback loop, reducing the bandwidth of the noise the system is able to cancel. This project intends to continue a previous work, in which analog adaptive filters were proposed for active noise control in headphones, searching ways to choose certain fixed parameters of the analog adaptive filters, in order to reduce overall system complexity and guarantee best performance. In addition, the performance of nonlinear (digital) adaptive filters will be compared with that of standard, linear adaptive filters.