Refactor and add doc string.

paddleaudio/paddleaudio/features/layers.py

@@ -261,12 +261,18 @@ class MFCC(nn.Layer):
                  sr: int=22050,
                  n_mfcc: int=40,
                  norm: str='ortho',
+                 dtype: str=paddle.float32,
                  **kwargs):
-        """[summary]
+        """Compute mel frequency cepstral coefficients(MFCCs) feature of given waveforms.
+
         Parameters:
-            sr (int, optional): [description]. Defaults to 22050.
-            n_mfcc (int, optional): [description]. Defaults to 40.
-            norm (str, optional): [description]. Defaults to 'ortho'.
+            sr(int): the audio sample rate.
+                The default value is 22050.
+            n_mfcc (int, optional): Number of cepstra in MFCC. Defaults to 40.
+            norm(str|float): the normalization type in computing fbank matrix. Slaney-style is used by default.
+                You can specify norm=1.0/2.0 to use customized p-norm normalization.
+            dtype(str): the datatype of fbank matrix used in the transform. Use float64 to increase numerical
+                accuracy. Note that the final transform will be conducted in float32 regardless of dtype of fbank matrix.
         """
         super(MFCC, self).__init__()
         self._log_melspectrogram = LogMelSpectrogram(sr=sr, **kwargs)