diff --git a/examples/passthrough.py b/examples/passthrough.py
index eb329ae..b9d1983 100755
--- a/examples/passthrough.py
+++ b/examples/passthrough.py
@@ -29,7 +29,16 @@ def __init__(self, args):
         self.idx = 0
         self.total_bytes = 0
         self.queue = queue.SimpleQueue()
-        self.data, self.sr = sf.read(args.input_file, dtype='int16', always_2d=True)
+
+        info = sf.info(str(args.input_file))
+        if info.subtype == 'PCM_16':
+            dtype = 'int16'
+        elif info.subtype == 'PCM_32':
+            dtype = 'int32'
+        else:
+            raise ValueError(f'WAV input data type must be either PCM_16 or PCM_32: Got {info.subtype}')
+
+        self.data, self.sr = sf.read(args.input_file, dtype=dtype, always_2d=True)
 
         self.encoder = pyflac.StreamEncoder(
             write_callback=self.encoder_callback,
diff --git a/pyflac/decoder.py b/pyflac/decoder.py
index bc8b80a..625b957 100644
--- a/pyflac/decoder.py
+++ b/pyflac/decoder.py
@@ -160,6 +160,8 @@ def __init__(self,
 
         self._done = False
         self._buffer = deque()
+        self._event = threading.Event()
+        self._lock = threading.Lock()
         self.write_callback = write_callback
 
         rc = _lib.FLAC__stream_decoder_init_stream(
@@ -201,7 +203,10 @@ def process(self, data: bytes):
         Args:
             data (bytes): Bytes of FLAC data
         """
+        self._lock.acquire()
         self._buffer.append(data)
+        self._lock.release()
+        self._event.set()
 
     def finish(self):
         """
@@ -226,6 +231,7 @@ def finish(self):
         # Instruct the decoder to finish up and wait until it is done
         # --------------------------------------------------------------
         self._done = True
+        self._event.set()
         self._thread.join(timeout=3)
         super().finish()
         if self._error:
@@ -316,13 +322,11 @@ def _read_callback(_decoder,
     """
     decoder = _ffi.from_handle(client_data)
 
-    while len(decoder._buffer) == 0 and not (decoder._error or decoder._done):
-        # ----------------------------------------------------------
-        # Wait until there is something in the buffer, or an error
-        # occurs, or the end of the stream is reached.
-        # ----------------------------------------------------------
-        time.sleep(0.01)
-
+    # ----------------------------------------------------------
+    # Wait until there is something in the buffer, or an error
+    # occurs, or the end of the stream is reached.
+    # ----------------------------------------------------------
+    decoder._event.wait()
     if decoder._error:
         # ----------------------------------------------------------
         # If an error has been issued via the error callback, then
@@ -345,16 +349,28 @@ def _read_callback(_decoder,
     data = bytes()
     maximum_bytes = int(num_bytes[0])
     if len(decoder._buffer[0]) <= maximum_bytes:
+        decoder._lock.acquire()
         data = decoder._buffer.popleft()
+        decoder._lock.release()
         maximum_bytes -= len(data)
 
     if len(decoder._buffer) > 0 and len(decoder._buffer[0]) > maximum_bytes:
+        decoder._lock.acquire()
         data += decoder._buffer[0][0:maximum_bytes]
         decoder._buffer[0] = decoder._buffer[0][maximum_bytes:]
+        decoder._lock.release()
 
     actual_bytes = len(data)
     num_bytes[0] = actual_bytes
     _ffi.memmove(byte_buffer, data, actual_bytes)
+
+    # --------------------------------------------------------------
+    # If there is no more data to process from the buffer, then
+    # clear the event, the thread will await more data to process.
+    # --------------------------------------------------------------
+    if len(decoder._buffer) == 0 or (len(decoder._buffer) > 0 and len(decoder._buffer[0]) == 0):
+        decoder._event.clear()
+
     return _lib.FLAC__STREAM_DECODER_READ_STATUS_CONTINUE
 
 
@@ -452,3 +468,4 @@ def _error_callback(_decoder,
         _lib.FLAC__StreamDecoderErrorStatusString[status]).decode()
     decoder.logger.error(f'Error in libFLAC decoder: {message}')
     decoder._error = message
+    decoder._event.set()