Transliteration is representation of the characters of one alphabet (language) by the characters of another. The use of diacritics or digraphs solves the problem of different number of characters between the alphabets of the two languages.
Non-Arabic speaking members of the Andalus Arabic Choir are provided with lyrics of the Arabic songs transliterated into English. Here is an example:
Arabic verse
لمّـــا بَــدا يَتثَنّـــــــى أمان أمان أمان أمان
حُبّـي جَمـالُـه فَتَنــــّا أمان أمان أمان أمان
English transliterated verse:
lammã badã yataθanna aman aman aman aman
hubbi jamalu fatannã aman aman aman aman
Hear the Andalus Arabic Choir singing the above verse:
http://www.word-medex.com.au/mp3/lamma-section.mp3%20