Reduced speech and fast speech are very closely related. The fact that the articulation or speaking rate are subject to regional variation has been demonstrated several times (cf. Hahn & Siebenhaar 2016, 2019, Leemann 2017, Coats 2020). Whether the assimilation of sound sequences shows independent regional tendencies (due to dialect variation), or is linearly related to the respective articulation rate, has not yet been examined in detail. The talk explores the geolinguistic tendencies for different forms of phonetic assimilation in Central European German and examines their dependence on the respective articulation rate. For this purpose, readings of the German version of the Aesop fable "the North Wind and the Sun" from the "Deutsch heute"-corpus are analyzed (cf. Kleiner 2015). This mate-rial represents the standard intended reading pronunciation of 327 speak-ers (males, aged 17–20, locals) from 165 locations in the study area. In most cases, recordings and the annotated segmentations of two speakers per location are available. Both word-internal and external contexts are taken into account, as well as articulatory and voicing assimilations. To visualize the spatial distributions of these tendencies the values are mapped with arcGIS (ESRI 2016). As a further source of explanation these maps are compared to corresponding findings from the “Kleiner Deutscher Sprachatlas (KDSA)” (Veith et al. 1984–1999) for German dialects.