Triads, Emphatics and Interdentals in Arabic Sound System Typology Alex Bellem University of Salford There is much discussion in the literature of the Arabic emphatics, with a wide range of studies focusing on the phonetic correlates (both articulatory and acoustic) of ‘emphatic’ and a wide range of studies focusing on the phonological representation and behaviour of ‘emphasis’. This paper shows how Arabic emphatics are an important part of a historical rearrangement within Arabic dialect sound systems that is ongoing. To this end, the paper focuses on a little-discussed aspect of emphatics, that of laryngeal categories. I look firstly at the ejectives hypothesis and discuss the series of triads that may be set up for Common Semitic. I then discuss laryngeal categories and show how these are measured phonetically, in order to exemplify laryngeal categories in a number of different Arabic dialects (e.g. rural-Bedouinite Syrian, urban Syrian, gilit Mesopotamian, peninsular Arabian, etc). I then demonstrate how Arabic dialects can be classified as dyadic or triadic and briefly note the changing function of ‘emphatic’ within Semitic. I argue that while laryngeal categories may be measured phonetically, dialectal variation is not just due to phonetic mapping, but is a part of the sound system. The functional change of ‘emphatic’ within Arabic sound systems has allowed the triad / dyad series to line up differently, so that in dialects where the 3-way laryngeal contrast has merged to a 2-way contrast, we find a series of dyadic contrasts (between t-d, −t-−d, etc). A factor which is relevant to this is the retention or neutralisation of the interdental series. I demonstrate this for Baghdadi and Damascene Arabic. However, the extent to which this re-lining up is itself still in transition is not clear. That is, we can find a strong correlation between interdental loss and 2-way laryngeal contrast dialects, as I show for Mashriqi Arabic dialects, although we are likely to see some exceptions, exemplifying a continuum (or trajectory of development) between the two systems. I conclude by discussing why it is important to look at emphatics in the context of their position within the larger sound system, and how this is a crucial aspect in setting up a typology of Arabic dialectal sound systems.