Gnome sounds are based on the ESD mixing system (allowing to play different sounds at the same time with the same card), which is itself based on the OSS sound service.

The problem is that it does not work by default with a Debian Testing system.

And if you try to start Esd in a terminal, you get :

$ esd
/dev/dsp: No such file or directory

First, you have to make sure to have the right packages set up (we consider that you keep using the more modern Alsa sound service instead of OSS) :

$ aptitude install alsa-oss gstreamer0.10-esd

But still, the /dev/dsp device will be missing.

The solution is to create this peripheral manually :

$ mknod /dev/dsp c 14 3

Problem : the next time you boot your machine, the device will be deleted.

Udev, the new device manager, load the peripherals dynamically, when they are detected (part of the kernel or included as a module).

If you want to check that Udev is in use on your machine :

$ ps -ef | grep udevd

Our problem is that a module – snd-pcm-oss – is not loaded at startup. We are using Alsa but we want to be able to use the deprecated OSS, still required by some applications.

The snd-pcm-oss module is emulating OSS for use with the Alsa system.
So, you need to do :

$ echo snd-pcm-oss >> /etc/modules

.. and the module will be started at the boot time, creating the suitable /dev/dsp.