Error:: Linux: can't open /dev/dsp

Go to your home directory and open the .festivalrc (if it is not there, just create it)
$cd
$sudo gedit .festivalrc
add the following line in this file and save:
(Parameter.set 'Audio_Command "aplay -q -c 1 -t raw -f s16 -r $SR $FILE")
(Parameter.set 'Audio_Method 'Audio_Command)