could have resulted in al- through a process of syncope so the alif in lā and the vowel over the lām were dropped, resulting in a sukūn (an Arabic diacritic) over the lām, and a volatile or elidable hamza was added to compensate for that. David Testen argues against both of these explanations. He says that there is no corroboratory evidence for either metathesis or syncope. Arabic la hypothesis It is possible that al- comes from the same root as the asseverative-cum-precative particle, la-; it is the la- used at the beginning of nominal sentences for emphasis. Phonology The phonology of al- is the study of its constituent letters and vowels, and of its pronunciation in different dialects and in different lexical circumstances. The hamza in al- A classical (and largely one-sided) debate in regards to al- is whether the hamza is volatile or not. The majority opinion is that of Sibawayh (d. ca. 797), who considers the hamza volatile. In his opinion, the hamza neither is part of al- nor contributes to the definiteness of the following word. Khalīl, Ibn Keisān and Akhfash, on the other hand, consider the hamza not to be volatile. There is a further debate among the proponents of the second theory. Some do not consider the hamza volatile and assert that it contributes to the definiteness of the following word. Others assert that the hamza contributes to the definiteness of the following word but is still volatile. In his defence, Khalīl argues that when a word prefixed with al- is preceded by the interrogative hamza, the two hamzas mix. For example, when the word al-āna (now) is prefixed with it, the result is āl-āna. Clearly, the hamza of al- does not drop in this case even though there is no further purpose for it. Khalīl further argues that the only reason the hamza in al- is ever dropped is not that it is volatile but that it is used too much. When asked why the lām in al- was not simply given a vowel if it is so heavily used and it needs to be easier to pronounce, followers of Khalīl said that if the lām had been given a fatḥa, it would have been confused with the asseverative-cum-precative particle. Had it been given a kasra, it would have been confused with the genitival particle. It could not have been given a ḍamma for