code: def testZeroNatural(self):
      # zero input should return dct(lin2db(0)). Try with different sizes
      size = 1025
      val = 0.0
      expected = DCT(inputSize=40, outputSize=13)(
          [val for x in range(40)]
      )
      while size > 256:
          bands, mfcc = MFCC(inputSize=size, logType="natural")(
              zeros(size)
          )
          self.assertEqualVector(mfcc, expected)
  
          # also assess that the thresholding is working
          self.assertTrue(
              not np.isnan(mfcc).any() and not np.isinf(mfcc).any()
          )
          size = int(size / 2)
  
file_path: essentia/test/src/unittests/spectral/test_mfcc.py
imports: from essentia_test import *
  from math import *
  import numpy
label_desc: Use image node_id 8 for calling the TestMFCC obj's underlying member method code with example usage: obj.testZeroNatural() without return types