Optimal and Adaptive Virtual Unidirectional Sound Source in 
                        Active Noise Control

<table>Noise N2 (broadband noise
700–800 Hz) attenuation. —  Spectrum with
ANC, - - -  spectrum without ANC.</table>

Advances in Acoustics and Vibration

Figure 13: Optimal and Adaptive Virtual Unidirectional Sound Source in 
                        Active Noise Control 