diff --git a/setup.py b/setup.py
index 1758a6d..256b918 100644
--- a/setup.py
+++ b/setup.py
@@ -12,12 +12,12 @@ with open("HISTORY.rst") as history_file:
 
 requirements = [
     "klepto==0.1.6",
-    "numpy==1.16.4",
+    "numpy~=1.16.4",
     "inflect==0.2.5",
     "librosa==0.6.0",
-    "scipy==1.3.0",
+    "scipy~=1.3.0",
     "Unidecode==1.0.22",
-    "torch==1.1.0",
+    "torch~=1.1.0",
     "PyAudio==0.2.11"
 ]
 
@@ -53,7 +53,7 @@ setup(
     test_suite="tests",
     tests_require=test_requirements,
     url="https://github.com/malarinv/tacotron2",
-    version="0.2.0",
+    version="0.3.0",
     zip_safe=False,
     entry_points={"console_scripts": ("tts_debug = taco2.tts:main",)},
 )
diff --git a/taco2/hparams.py b/taco2/hparams.py
index 6c632dc..3f15f20 100644
--- a/taco2/hparams.py
+++ b/taco2/hparams.py
@@ -35,7 +35,7 @@ class HParams(object):
     # Audio Parameters             #
     ################################
     max_wav_value = 32768.0
-    sampling_rate = 16000
+    sampling_rate = 22050
     filter_length = 1024
     hop_length = 256
     win_length = 1024
diff --git a/taco2/tts.py b/taco2/tts.py
index 3c51885..5c505fe 100644
--- a/taco2/tts.py
+++ b/taco2/tts.py
@@ -15,9 +15,9 @@ from .text import text_to_sequence
 from .denoiser import Denoiser
 from .audio_processing import griffin_lim, postprocess_audio
 
-TTS_SAMPLE_RATE = 22050
 OUTPUT_SAMPLE_RATE = 22050
-# OUTPUT_SAMPLE_RATE = 16000
+GL_ITERS = 30
+VOCODER_MODEL = "wavglow"
 
 # config from
 # https://github.com/NVIDIA/waveglow/blob/master/config.json
@@ -37,7 +37,7 @@ class TTSModel(object):
     def __init__(self, tacotron2_path, waveglow_path, **kwargs):
         super(TTSModel, self).__init__()
         hparams = HParams(**kwargs)
-        hparams.sampling_rate = TTS_SAMPLE_RATE
+        self.hparams = hparams
         self.model = Tacotron2(hparams)
         if torch.cuda.is_available():
             self.model.load_state_dict(torch.load(tacotron2_path)["state_dict"])
@@ -78,7 +78,7 @@ class TTSModel(object):
             )
         else:
             self.synth_speech = klepto.safe.inf_cache(cache=self.k_cache)(
-                self.synth_speech_gl
+                self.synth_speech_fast
             )
         self.taco_stft = TacotronSTFT(
             hparams.filter_length,
@@ -101,23 +101,40 @@ class TTSModel(object):
             )
         return mel_outputs_postnet
 
-    def synth_speech_array(self, text):
+    def synth_speech_array(self, text, vocoder):
         mel_outputs_postnet = self.generate_mel_postnet(text)
 
-        with torch.no_grad():
-            audio_t = self.waveglow.infer(mel_outputs_postnet, sigma=0.666)
-            audio_t = self.denoiser(audio_t, 0.1)[0]
-        audio = audio_t[0].data.cpu().numpy()
+        if method == "wavglow":
+            with torch.no_grad():
+                audio_t = self.waveglow.infer(mel_outputs_postnet, sigma=0.666)
+                audio_t = self.denoiser(audio_t, 0.1)[0]
+            audio = audio_t[0].data.cpu().numpy()
+        elif method == "gl":
+            mel_decompress = self.taco_stft.spectral_de_normalize(mel_outputs_postnet)
+            mel_decompress = mel_decompress.transpose(1, 2).data.cpu()
+            spec_from_mel_scaling = 1000
+            spec_from_mel = torch.mm(mel_decompress[0], self.taco_stft.mel_basis)
+            spec_from_mel = spec_from_mel.transpose(0, 1).unsqueeze(0)
+            spec_from_mel = spec_from_mel * spec_from_mel_scaling
+            audio = griffin_lim(
+                torch.autograd.Variable(spec_from_mel[:, :, :-1]),
+                self.taco_stft.stft_fn,
+                60,
+            )
+            audio = audio.squeeze()
+            audio = audio.cpu().numpy()
+        else:
+            raise ValueError("vocoder arg should be one of [wavglow|gl]")
         return audio
 
-    def synth_speech(self, text):
-        audio = self.synth_speech_array(text)
+    def synth_speech(self, text, speed: 1.0, sample_rate=OUTPUT_SAMPLE_RATE):
+        audio = self.synth_speech_array(text, VOCODER_MODEL)
 
         return postprocess_audio(
-            audio, src_rate=TTS_SAMPLE_RATE, dst_rate=OUTPUT_SAMPLE_RATE
+            audio, src_rate=self.hparams.sample_rate, dst_rate=sample_rate, tempo=speed
         )
 
-    def synth_speech_gl(self, text, griffin_iters=60):
+    def synth_speech_fast(self, text, speed: 1.0, sample_rate=OUTPUT_SAMPLE_RATE):
         mel_outputs_postnet = self.generate_mel_postnet(text)
 
         mel_decompress = self.taco_stft.spectral_de_normalize(mel_outputs_postnet)
@@ -129,13 +146,13 @@ class TTSModel(object):
         audio = griffin_lim(
             torch.autograd.Variable(spec_from_mel[:, :, :-1]),
             self.taco_stft.stft_fn,
-            griffin_iters,
+            GL_ITERS,
         )
         audio = audio.squeeze()
         audio = audio.cpu().numpy()
 
         return postprocess_audio(
-            audio, tempo=0.6, src_rate=TTS_SAMPLE_RATE, dst_rate=OUTPUT_SAMPLE_RATE
+            audio, tempo=speed, src_rate=self.hparams.sample_rate, dst_rate=sample_rate,
         )