Global active control of broadband noise from small axial cooling fans, Part 2

The multi-channel filtered-x LMS algorithm has previously been used for feed-forward control of the tonal noise of a small axial cooling fan [Gee and Sommerfeldt, ‘‘Application of theoretical modeling to multichannel active control of cooling fan noise,’’ J. Acoust. Soc. Am. 115, 228–236 (2004)]. With much of the tonal noise content removed it becomes desirable to reduce the broadband fan noise. A previous study demonstrated the feasibility of achieving desirable broadband attenuation by means of active feedback control. Measurements will be presented and discussed that have an impact on the control achievable. Experimental control results will be presented.