Optimal and Adaptive Virtual Unidirectional Sound Source in 
                        Active Noise Control

<table>Attenuation (in dB) of tonal sounds for adaptive filter tuning. — 
RLS algorithm, - - -  FXLMS
algorithm.</table>

Advances in Acoustics and Vibration

Figure 10: Optimal and Adaptive Virtual Unidirectional Sound Source in 
                        Active Noise Control 