can't open /dev/dsp

If festival returns the following error message:

Linux: can't open /dev/dsp

Switch to ALSA output by adding these lines to the end of your .festivalrc file, or to /usr/share/festival/festival.scm (source):

(Parameter.set 'Audio_Method 'Audio_Command)
(Parameter.set 'Audio_Command "aplay -q -c 1 -t raw -f s16 -r $SR $FILE")