Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

<table>Variation of fan noise spectra reduction by adaptive duct liner II of AAC technology I model with mobile reflective plate position change. Fan rotational speed 4000 rom; acoustic measuring point 60 deg.; mobile reflective plate; parallel shift, acoustic absorbent material; poal + acousticel.</table>

Advances in Acoustics and Vibration

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Figure 11

Figure 11: Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner 