Thank you sag47. That was spot on! The code that works is:
# mp3 converter using avconv
read -p "Enter number of first track : " t1
read -p "Enter number of last track : " tn
echo "Converting tracks $t1 to "$tn
# convert tracks
while [ $n -le $tn ]
/usr/bin/avconv -y -i "/run/user/1000/gvfs/cdda:host=sr0/Track $n.wav" -acodec libmp3lame -b:a 320k -ac 2 -ar 44100 "/home/ofilms/Music/Converted/Track $n.mp3"
n=$(( n+1 ))
Now to read the bash manual and refine the script to read preset text files for conversion settings! Thank you.