Audio PyQt5音频无响应

我正在尝试制作一个基于pyqt5的音频播放器。hovewer在网站包中阅读了这些示例，并访问了“我无法前进一步”，似乎没有音频输出。提前感谢，这是我当前的代码（python3.3）

import sys
from PyQt5 import QtGui, QtCore, QtWidgets, QtMultimedia

class Window(QtWidgets.QWidget):

    def __init__(self, parent = None):    
        QtWidgets.QWidget.__init__(self, parent)

        format = QtMultimedia.QAudioFormat()
        format.setSampleRate(44100)
        format.setSampleSize(16)
        format.setChannelCount(1)
        format.setCodec("audio/wav")
        format.setByteOrder(QtMultimedia.QAudioFormat.LittleEndian)
        format.setSampleType(QtMultimedia.QAudioFormat.SignedInt)
        self.output = QtMultimedia.QAudioOutput(QtMultimedia.QAudioDeviceInfo.defaultOutputDevice(), format, self)

        self.file=QtCore.QFile()
        self.file.setFileName("data/voicemail/99dc6d529c0c5d6b2ec5cda7b26cc1bb9af58bd4774d161f66186f62bf3093cd.wav")
        self.file.open(QtCore.QIODevice.ReadOnly)
        self.file.seek(44)
        self.output.start(self.file)

        #self.file.close()

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    window = Window()
    window.show()
    sys.exit(app.exec_())