diff --git a/grpc/mic_stt_client.py b/grpc/mic_stt_client.py
new file mode 100755
index 0000000..9629b48
--- /dev/null
+++ b/grpc/mic_stt_client.py
@@ -0,0 +1,98 @@
+#!/usr/bin/python3
+
+import argparse
+import grpc
+
+import pyaudio
+import sys
+
+import stt_service_pb2
+import stt_service_pb2_grpc
+
+# config
+CHUNK_SIZE = 4000
+BUFFER_SIZE = 8000
+FORMAT = pyaudio.paInt16
+CHANNELS = 1
+RATE = None
+DEVICE_INDEX = None
+
+p = pyaudio.PyAudio()
+
+
+def list_devices():
+    print("List of all devices detected by PyAudio (Index - Name) :")
+    print("-------------------------------------------------------")
+    for x in range(p.get_device_count()):
+        info_dic = p.get_device_info_by_index(x)
+        if info_dic['maxInputChannels'] > 0:
+            print(str(x) + " - " + info_dic['name'])
+
+def gen():
+    specification = stt_service_pb2.RecognitionSpec(
+        partial_results=True,
+        audio_encoding='LINEAR16_PCM',
+        sample_rate_hertz=16000
+    )
+    streaming_config = stt_service_pb2.RecognitionConfig(specification=specification)
+
+    yield stt_service_pb2.StreamingRecognitionRequest(config=streaming_config)
+
+    stream = p.open(
+        format=FORMAT
+        ,channels=CHANNELS
+        ,rate=int(RATE)
+        ,input=True
+        ,input_device_index=DEVICE_INDEX
+        ,frames_per_buffer=BUFFER_SIZE)
+
+    stream.start_stream()
+
+    while True:
+        data = stream.read(CHUNK_SIZE)
+        if len(data) == 0:
+            break
+        else:
+            yield stt_service_pb2.StreamingRecognitionRequest(audio_content=data)
+
+
+
+def run():
+    channel = grpc.insecure_channel('localhost:5001')
+    stub = stt_service_pb2_grpc.SttServiceStub(channel)
+    it = stub.StreamingRecognize(gen())
+
+    try:
+        for r in it:
+            try:
+                print('Start chunk: ')
+                for alternative in r.chunks[0].alternatives:
+                    print('alternative: ', alternative.text)
+                    print('alternative_confidence: ', alternative.confidence)
+                    print('words: ', alternative.words)
+                print('Is final: ', r.chunks[0].final)
+                print('')
+            except LookupError:
+                print('No available chunks')
+    except grpc._channel._Rendezvous as err:
+        print('Error code %s, message: %s' % (err._state.code, err._state.details))
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--device-index', required=False, help='input device index')
+    parser.add_argument('--list-device', required=False, action="store_true", help='display device list') #just a flag
+    args = parser.parse_args()
+
+    if args.list_device == True:
+        list_devices()
+        sys.exit()
+
+    if args.device_index is not None:
+        DEVICE_INDEX = args.device_index
+        RATE = p.get_device_info_by_index[DEVICE_INDEX]['defaultSampleRate']
+    else :
+        DEVICE_INDEX = p.get_default_input_device_info()['index']
+        RATE = p.get_default_input_device_info()['defaultSampleRate']
+    
+    run()
diff --git a/grpc/stt_server.py b/grpc/stt_server.py
index 3ddf6dc..dc38e54 100755
--- a/grpc/stt_server.py
+++ b/grpc/stt_server.py
@@ -68,7 +68,10 @@ def get_response(self, json_res):
         else:
              words = [self.get_word_info(x) for x in res.get('result', [])]
              confs = [w.confidence for w in words]
-             alt_conf = sum(confs) / len(confs)
+             if len(confs) == 0:
+                 alt_conf = 0
+             else : 
+                 alt_conf = sum(confs) / len(confs)
              alternatives = [stt_service_pb2.SpeechRecognitionAlternative(text=res['text'], words=words, confidence=alt_conf)]
              chunks = [stt_service_pb2.SpeechRecognitionChunk(alternatives=alternatives, final=True)]
              return stt_service_pb2.StreamingRecognitionResponse(chunks=chunks)