Reduction of centrifugal fan noise by use of resonatorsKoopmann, G.; Neise, W. · The Journal of the Acoustical Society of America · 1980

The use of resonators to silence centrifugal blowersG.H. Koopmann; W. Neise · 1982

Active source cancellation of the blade tone fundamental and harmonics in centrifugal fansG.H. Koopmann; D.J. Fox; W. Neise · 1988