Comment 2 for bug 535470

Sorry, I forgot the link to Debian bug tracker: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=563353
And here's the technical info from that report:

Installing libcanberra-gstreamer does not enable the gstreamer backend. libcanberra still tries to use ALSA directly.

Verified:
- gstreamer and all appropriate plugins are installed
- gstreamer is set to use appropriate sink (oss4sink in my case)
- Sample .ogg and .wav files exist and are playable through gstreamer
- canberra-gtk-play works with ALSA emulation

Sample output (with no ALSA emulation enabled):
canberra-gtk-play --file=test.wav
ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
ALSA lib conf.c:4154:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4154:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
ALSA lib conf.c:4154:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4633:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2211:(snd_pcm_open_noupdate) Unknown PCM default
Failed to play sound: File or data not found