Add normalization to steering vector solutions in MVDR Module (#1765)

examples/beamforming/mvdr.py

@@ -272,7 +272,9 @@ class MVDR(torch.nn.Module):
             numerator = torch.linalg.solve(psd_n, stv).squeeze(-1)  # (..., freq, channel)
             # denominator = stv^H @ psd_n.inv() @ stv
             denominator = torch.einsum("...d,...d->...", [stv.conj().squeeze(-1), numerator])
-            beamform_vector = numerator / (denominator.real.unsqueeze(-1) + eps)
+            # normalzie the numerator
+            scale = stv.squeeze(-1)[..., self.ref_channel, None].conj()
+            beamform_vector = numerator * scale / (denominator.real.unsqueeze(-1) + eps)
 
         return beamform_vector
 
@@ -315,8 +317,7 @@ class MVDR(torch.nn.Module):
         phi = torch.linalg.solve(psd_n, psd_s)  # psd_n.inv() @ psd_s
         stv = torch.einsum("...fec,...c->...fe", [phi, reference_vector])
         stv = stv.unsqueeze(-1)
-        for _ in range(3):
-            stv = torch.matmul(phi, stv)
+        stv = torch.matmul(phi, stv)
         stv = torch.matmul(psd_s, stv)
         return stv