diff --git a/util/audio.py b/util/audio.py
index eacefd6..581511a 100644
--- a/util/audio.py
+++ b/util/audio.py
@@ -111,7 +111,6 @@ def _stft_parameters():
 # Conversions:
 
 _mel_basis = None
-_inv_mel_basis = None
 
 def _linear_to_mel(spectrogram):
   global _mel_basis
@@ -119,12 +118,6 @@ def _linear_to_mel(spectrogram):
     _mel_basis = _build_mel_basis()
   return np.dot(_mel_basis, spectrogram)
 
-def _mel_to_linear(mel_spectrogram):
-  global _inv_mel_basis
-  if _inv_mel_basis is None:
-    _inv_mel_basis = np.linalg.pinv(_build_mel_basis())
-  return np.maximum(1e-10, np.dot(_inv_mel_basis, mel_spectrogram))
-
 def _build_mel_basis():
   n_fft = (hparams.num_freq - 1) * 2
   return librosa.filters.mel(hparams.sample_rate, n_fft, n_mels=hparams.num_mels)