void choose_speaker_pairs ();
void sort_2D_lss (int* sorted_lss);
int calc_2D_inv_tmatrix (double azi1,double azi2, double* inv_mat);
void choose_speaker_pairs ();
void sort_2D_lss (int* sorted_lss);
int calc_2D_inv_tmatrix (double azi1,double azi2, double* inv_mat);