Modal Windows

In the time-domain implementation of NFC-HOA it is possible to apply different weighting factors to each mode of the driving signals in the circular harmonics domain by changing the conf.modal_window configuration parameter. Using a weighting window that is smoother than the default rectangular window, causes a concentration of energy to fewer loudspeakers.

conf = SFS_config;
conf.dimension = '2.5D';
conf.secondary_sources.number = 16;
conf.secondary_sources.geometry = 'circular';
conf.secondary_sources.size = 3;
conf.resolution = 300;
conf.plot.usedb = true;
conf.t0 = 'source';
X = [-2,2];
Y = [-2,2];
Z = 0;
conf.modal_window = 'rect';  % default
sound_field_imp_nfchoa(X,Y,Z,[0 -1 0],'pw',0,conf);
%print_png('sound_field_imp_nfchoa_25d_dB_rect.png');
conf.modal_window = 'max-rE';
sound_field_imp_nfchoa(X,Y,Z,[0 -1 0],'pw',0,conf);
%print_png('sound_field_imp_nfchoa_25d_dB_max-rE.png');
conf.modal_window = 'kaiser';
conf.modal_window_parameter = 1.0;
sound_field_imp_nfchoa(X,Y,Z,[0 -1 0],'pw',0,conf);
%print_png('sound_field_imp_nfchoa_25d_dB_kaiser.png');
conf.modal_window = 'tukey';
conf.modal_window_parameter = 0.5;
sound_field_imp_nfchoa(X,Y,Z,[0 -1 0],'pw',0,conf);
%print_png('sound_field_imp_nfchoa_25d_dB_tukey.png');

Fig. 21 Sound pressure in decibel of a broadband impulse plane wave synthesized by 2.5D NFC-HOA using a rectangular window. The plane wave propagates into the direction of (0,-1,0).

Fig. 22 Sound pressure in decibel of a broadband impulse plane wave synthesized by 2.5D NFC-HOA using a max-rE window. The plane wave propagates into the direction of (0,-1,0).

Fig. 23 Sound pressure in decibel of a broadband impulse plane wave synthesized by 2.5D NFC-HOA using a Kaiser window. The plane wave propagates into the direction of (0,-1,0).

Fig. 24 Sound pressure in decibel of a broadband impulse plane wave synthesized by 2.5D NFC-HOA using a modified Tukey window. The plane wave propagates into the direction of (0,-1,0).