class_docstr: Test audio preprocess functions.
code: def test_melspec(self):
      mel = MelSpec(
          sample_rate=self.params["sample_rate"],
          window_length=self.params["window_length"],
          hop_length=self.params["hop_length"],
          f_min=self.params["f_min"],
          f_max=self.params["f_max"],
          n_mels=self.params["n_mels"],
          naf_mode=self.params["naf_mode"],
          mel_log=self.params["mel_log"],
          spec_norm=self.params["spec_norm"],
      )
  
      outs = mel(self.audio)
      self.assertTrue(outs.shape == (2, 10, 21))
  
file_path: towhee/tests/unittests/models/utils/test_audio_preprocess.py
imports: import unittest
  import torch
  import numpy
  from towhee.models.utils.audio_preprocess import MelSpec, preprocess_wav
label_desc: Use image node_id 1 for calling the TestAudioPreprocess obj's underlying member method code with example usage: obj.test_melspec() without return types