Phonology
Despite the strong differences among the North Frisian dialects there are still some traits of phonology that are more or less common to all dialects. Among them is the vowel reduction from ɪ to a, which is mostly complete in the central dialects, but has only arrived at the stage ɛ or eː in the periphery. For example, the word "fish" translates to Mooring fasch, Fering-Öömrang fask, but Söl'ring fesk (cf. Low German: Fisch/Fisk, Danish: fisk, German: Fisch, Dutch: vis).
The distribution of the lenition of the unvoiced plosives p, t and k is similar as these consonants have become voiced plosives and partially even developed to fricatives in the central dialects. This can be demonstrated from the verb "to know": Mooring waase, Fering-Öömrang wed, Sölring weet, Halunder wet (cf. West Frisian witte, Low German weten, German wissen).
The North Frisian dialects differ from modern Standard German by a more diverse system of vowels and consonants. All dialects have in common an additional line of palatalizations, which is uncommon for a Germanic language. Until recently an additional number of dental consonants that changed the meaning of a word was known in the dialect of Föhr. In general it can be noted that the insular dialects feature a relatively complicated consonantal system while the mainland dialects have more diverse vowels.
As a recent development, the phonological system of the North Frisian dialects is strongly being influenced by Standard German and is slowly adapting to the system of the German language.
Read more about this topic: North Frisian Language