diff --git a/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py b/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py
index 538646948..f774e5548 100644
--- a/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless7/zipformer.py
@@ -307,17 +307,17 @@ class Zipformer2(EncoderInterface):
                           feature_mask_dropout_prob).to(x.dtype)
 
         # frame_mask_max2 has additional frames masked, about twice the number.
-        frame_mask_max2 = torch.logical_or(frame_mask_max1,
-                                           (torch.rand(num_frames_max, batch_size, 1,
-                                                       device=x.device) >
-                                            feature_mask_dropout_prob).to(x.dtype))
+        frame_mask_max2 = torch.logical_and(frame_mask_max1,
+                                            (torch.rand(num_frames_max, batch_size, 1,
+                                                        device=x.device) >
+                                             feature_mask_dropout_prob).to(x.dtype))
 
 
         # frame_mask_max3 has additional frames masked, about 3 times the number.
-        frame_mask_max3 = torch.logical_or(frame_mask_max2,
-                                           (torch.rand(num_frames_max, batch_size, 1,
-                                                       device=x.device) >
-                                            feature_mask_dropout_prob).to(x.dtype))
+        frame_mask_max3 = torch.logical_and(frame_mask_max2,
+                                            (torch.rand(num_frames_max, batch_size, 1,
+                                                        device=x.device) >
+                                             feature_mask_dropout_prob).to(x.dtype))
 
         # dim: (num_frames_max, batch_size, 3)
         frame_mask_max = torch.cat((frame_mask_max1, frame_mask_max2, frame_mask_max3), dim=-1)