diff --git a/paddlespeech/vector/io/signal_processing.py b/paddlespeech/vector/io/signal_processing.py
index ee939bdb1..143d2a80a 100644
--- a/paddlespeech/vector/io/signal_processing.py
+++ b/paddlespeech/vector/io/signal_processing.py
@@ -37,7 +37,7 @@ def compute_amplitude(waveforms, lengths=None, amp_type="avg", scale="linear"):
             out = paddle.mean(paddle.abs(waveforms), axis=1, keepdim=True)
         else:
             wav_sum = paddle.sum(paddle.abs(waveforms), axis=1, keepdim=True)
-            out = wav_sum / lengths
+            out = wav_sum / lengths.astype(wav_sum.dtype)
     elif amp_type == "peak":
         out = paddle.max(paddle.abs(waveforms), axis=1, keepdim=True)
     else: