code: def testLinear2MelMatrix(self, n_mel, n_spec):
      l2m = spectral_ops.linear_to_mel_weight_matrix(
          num_mel_bins=n_mel,
          num_spectrogram_bins=n_spec,
          sample_rate=16000,
          lower_edge_hertz=0.0,
          upper_edge_hertz=8000.0,
      )
      self.assertEqual(l2m.shape, (n_spec, n_mel))
  
file_path: magenta/magenta/models/gansynth/lib/spectral_ops_test.py
imports: from absl.testing import parameterized
  from magenta.models.gansynth.lib import spectral_ops
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 2 for calling the SpectralOpsTest obj's underlying member method code with example usage: obj.testLinear2MelMatrix(n_mel, n_spec) without return types