diff --git a/egs/librispeech/ASR/pruned_transducer_stateless7/optim.py b/egs/librispeech/ASR/pruned_transducer_stateless7/optim.py
index 009755859..75b975711 100644
--- a/egs/librispeech/ASR/pruned_transducer_stateless7/optim.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless7/optim.py
@@ -953,13 +953,20 @@ param_rms_smooth1: Smoothing proportion for parameter matrix, if assumed rank of
         batch_size = rms.shape[0]
         size = rms.numel() // batch_size
         rms = rms ** param_pow
-        smooth = (smooth0 +
-                  (smooth1 - smooth0) * size / (size + rank))
+
+
+        # want expr to be of the form: smooth = alpha * size / (beta*rank + size)
+        # from rank==0, we get smooth0 = alpha * size/size, so alpha = smooth0.
+        # from setting rank==size, we get smooth1 = alpha * size / (beta*size * size) = alpha/(1+beta),
+        # so smooth1 == smooth0 / (1+beta), so (1+beta) = smooth0/smooth1, so beta=smooth0/smooth1 - 1
+        smooth = smooth0 * size / ((smooth0/smooth1 - 1) * rank + size)
+
         mean = _mean(rms, exclude_dims=[0], keepdim=True)
         rms += eps + smooth * mean
         new_mean = (eps + (smooth + 1) * mean)  # mean of modified rms.
         ans = rms / new_mean
 
+
         if True:
             # Apply max_rms
             max_rms = 4.0