Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

<table>Fan noise spectra reduced by adaptive duct liner II of AAC technology I with and without mobile reflective plates. Fan speed 6000 rpm; measuring point 60 deg; with and without mobile reflective plates; acoustic absorbent material; poal + acousticel.</table>

Advances in Acoustics and Vibration

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Figure 13

Figure 13: Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner 