Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

<table>Variation of overall fan noise reduction by AAC technology III model with tunable perforated plate position change. Fan rotational speed 4000 rpm; acoustic measuring point 45 deg.; mobile reflective plate position fixed at 25 mm; parallel shift.</table>

Advances in Acoustics and Vibration

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Figure 17

Figure 17: Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner 