I suppose a brutally simple way would just be a loop:

Code:

tr '[A-Z]' '[a-z]' < inputfile | while read LINE
do
        STR=""
        set -- $LINE
        while [ "$#" -gt 0 ]
        do
                [ -f "wavdir/$1.wav" ] && STR="$STR wavdir/$1.wav"
                shift
        done

        [ ! -z "$STR" ] && play $STR
done

It converts all uppercase into lowercase, then reads every line, splits words on whitespace into $1 $2 ..., loops over $1...$N, and for every word matching a file inside wavdir/, adds it to a list of files to be played then plays it.

You need sox's play command for this...