diff --git a/paddlespeech/cls/exps/panns/deploy/predict.py b/paddlespeech/cls/exps/panns/deploy/predict.py
index 464685331..a6b735335 100644
--- a/paddlespeech/cls/exps/panns/deploy/predict.py
+++ b/paddlespeech/cls/exps/panns/deploy/predict.py
@@ -58,7 +58,7 @@ def extract_features(files: str, **kwargs):
 
         feature_extractor = LogMelSpectrogram(sr, **kwargs)
         feat = feature_extractor(paddle.to_tensor(waveforms[i]))
-        feat = paddle.transpose(feat, perm=[1, 0])
+        feat = paddle.transpose(feat, perm=[1, 0]).unsqueeze(0)
         feats.append(feat)
 
     return np.stack(feats, axis=0)