diff --git a/models.py b/models.py
index da233d02d..459ff619e 100644
--- a/models.py
+++ b/models.py
@@ -3,7 +3,7 @@
 import torch.nn as nn
 from torch.nn import Conv1d, ConvTranspose1d, AvgPool1d, Conv2d
 from torch.nn.utils import weight_norm, remove_weight_norm, spectral_norm
-from utils import init_weights, get_padding
+from utils import init_weights, get_padding, apply_mask
 
 LRELU_SLOPE = 0.1
 
@@ -32,14 +32,18 @@ def __init__(self, h, channels, kernel_size=3, dilation=(1, 3, 5)):
         ])
         self.convs2.apply(init_weights)
 
-    def forward(self, x):
+    def forward(self, x, valid_lengths=None):
         for c1, c2 in zip(self.convs1, self.convs2):
             xt = F.leaky_relu(x, LRELU_SLOPE)
             xt = c1(xt)
+            if valid_lengths is not None:
+                xt, valid_lengths = apply_mask(c1, xt, valid_lengths)
             xt = F.leaky_relu(xt, LRELU_SLOPE)
             xt = c2(xt)
+            if valid_lengths is not None:
+                xt, valid_lengths = apply_mask(c2, xt, valid_lengths)
             x = xt + x
-        return x
+        return x, valid_lengths
 
     def remove_weight_norm(self):
         for l in self.convs1:
@@ -60,12 +64,14 @@ def __init__(self, h, channels, kernel_size=3, dilation=(1, 3)):
         ])
         self.convs.apply(init_weights)
 
-    def forward(self, x):
+    def forward(self, x, valid_lengths=None):
         for c in self.convs:
             xt = F.leaky_relu(x, LRELU_SLOPE)
             xt = c(xt)
+            if valid_lengths is not None:
+                xt, valid_lengths = apply_mask(c, xt, valid_lengths)
             x = xt + x
-        return x
+        return x, valid_lengths
 
     def remove_weight_norm(self):
         for l in self.convs:
@@ -97,18 +103,24 @@ def __init__(self, h):
         self.ups.apply(init_weights)
         self.conv_post.apply(init_weights)
 
-    def forward(self, x):
+    def forward(self, x, valid_lengths=None):
         x = self.conv_pre(x)
+        if valid_lengths is not None:
+            x, valid_lengths = apply_mask(self.conv_pre, x, valid_lengths)
         for i in range(self.num_upsamples):
             x = F.leaky_relu(x, LRELU_SLOPE)
             x = self.ups[i](x)
+            if valid_lengths is not None:
+                x, valid_lengths = apply_mask(self.ups[i], x, valid_lengths)
             xs = None
             for j in range(self.num_kernels):
                 if xs is None:
-                    xs = self.resblocks[i*self.num_kernels+j](x)
+                    xs, valid_lengths = self.resblocks[i*self.num_kernels+j](x, valid_lengths)
                 else:
-                    xs += self.resblocks[i*self.num_kernels+j](x)
+                    xs_cal , valid_lengths = self.resblocks[i*self.num_kernels+j](x, valid_lengths)
+                    xs = xs + xs_cal
             x = xs / self.num_kernels
+        
         x = F.leaky_relu(x)
         x = self.conv_post(x)
         x = torch.tanh(x)
diff --git a/utils.py b/utils.py
index aa2a536e6..7084b0f00 100644
--- a/utils.py
+++ b/utils.py
@@ -56,3 +56,26 @@ def scan_checkpoint(cp_dir, prefix):
         return None
     return sorted(cp_list)[-1]
 
+def apply_mask(op, x, valid_lengths):
+    if op._get_name() == 'Conv1d':
+        kernel_size = op.kernel_size[0]
+        stride = op.stride[0]
+        padding = op.padding[0]
+        dilation = op.dilation[0] 
+        output_length = []
+        for i, length in enumerate(valid_lengths):
+            output_length.append((length + 2 * padding - (kernel_size - 1) * dilation - 1) // stride + 1)
+            x[i, :, output_length[i]:] = 0
+    elif op._get_name() == 'ConvTranspose1d':
+        kernel_size = op.kernel_size[0]
+        stride = op.stride[0]
+        padding = op.padding[0]
+        dilation = op.dilation[0]
+        output_length = []
+        for i, length in enumerate(valid_lengths):
+            output_length.append((length - 1) * stride - 2 * padding + (kernel_size - 1) * dilation + op.output_padding[0] + 1)
+            x[i, :, output_length[i]:] = 0
+    else:
+        return x, valid_lengths
+    return x, output_length
+