code: def _mel_to_linear(self, mel_spec):
      return np.maximum(1e-10, np.dot(self.inv_mel_basis, mel_spec))
  
imports: import librosa
  import soundfile
  import numpy
  import scipy.io.wavfile
  import scipy.signal
  from TTS.tts.utils.data import StandardScaler
label_desc: Use image node_id 13 for calling the AudioProcessor obj's underlying member method code with example usage: obj._mel_to_linear(mel_spec) and returns: np