no sound when run a python script with python-espeak

[Liunx]

hello, when i run the python-espeak in a command line such as ipython or python in the terminal, when i do
"from espeak import espeak espeak.synth('hello,world')", i can hear the sound, but when i write then into a script file,
i can get the sound, the result show below:
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.rear
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.center_lfe
ALSA lib pcm.c:2212:(snd_pcm_open_noupdate) Unknown PCM cards.pcm.side
bt_audio_service_open: connect() failed: Connection refused (111)
bt_audio_service_open: connect() failed: Connection refused (111)
bt_audio_service_open: connect() failed: Connection refused (111)
bt_audio_service_open: connect() failed: Connection refused (111)
ALSA lib pcm_dmix.c:957:(snd_pcm_dmix_open) The dmix plugin supports only playback stream
Cannot connect to server socket err = No such file or directory
Cannot connect to server socket
jack server is not running or cannot be started

i use ubuntu11.4-x86_64
regards.

[Liunx (liunx163)]

It's OK to run espeak-gui that written with python-espeak, and i also can get it work in the command line such as
ipython or python.