code: def test_normalize_volume_zero(self):
      input_audio = np.array([0.0, 0.1, 0.3, 0.5])
      expected_output = np.array([0.0, 0.0, 0.0, 0.0])
  
      output_audio = normalize_volume(
          audio=input_audio, volume_level=0.0
      )
  
      np.testing.assert_array_almost_equal(
          output_audio, expected_output
      )
  
imports: from pathlib import Path
  import librosa
  import numpy
  import pytest
  import torch
  from nemo.collections.tts.parts.utils.tts_dataset_utils import filter_dataset_by_duration, get_abs_rel_paths, get_audio_filepaths, load_audio, normalize_volume, stack_tensors
label_desc: Use image node_id 8 for calling the TestTTSDatasetUtils obj's underlying member method code with example usage: obj.test_normalize_volume_zero() without return types