Quando você usa pulseaudio , não precisa de /dev/dsp device. Pelo menos de acordo com essa fonte:
PulseAudio
For OSS applications, PulseAudio provides the
padsputility, which replaces device files such as/dev/dsp, tricking the applications into believing that they have exclusive control over the sound card. In reality, their output is rerouted through PulseAudio.