lontra@debian:~$ lsof /dev/dsp* /dev/snd/*
lsof: WARNING: can't stat() ext3 file system /dev/.static/dev
      Output information may be incomplete.
COMMAND    PID   USER   FD   TYPE DEVICE SIZE NODE NAME
esd       3380 lontra    5w   CHR   14,3      5889 /dev/dsp
mixer_app 3743 lontra   36u   CHR  116,0      5876 /dev/snd/controlC0