A feature of a number of regional accents of American English. The vowel æ is tensed, essentially meaning it is raised and often turns into a diphthong. ɛ, eə, or ɪə are the resulting qualities, depending on the particular accent in question.
The contexts in which ash tensing occurs vary from accent to accent and the situation is rather complex. In some accents the phenomenon is partially lexically conditioned. In Baltimore, for example, ash tensing occurs before n m f θ s and in the words bad, glad and mad, but not in other words ending in d. A further complication is that in some accents, notably those of Baltimore, Philadelphia and New York City, ash tensing has resulted in a phoneme split. For example, can (=metal container) has undergone tensing resulting in keən, whereas can (=be able) remains as kæn.
In areas where the accent has undergone the Northern cities shift ash tensing operates in all environments.