Fricatives in place of other sounds

Some varieties of English, notably Liverpool and Irish English, regularly use fricatives for sounds that are produced as plosives in other varieties. These fricatives correspond to the places of articulation of plosives, so there are bilabial fricatives, alveolars and velars corresponding to the plosives  . How these fricative sounds should be transcribed is a matter of debate. In some varieties of English, especially Liverpool and Irish, such sounds are normal productions, not just common productions, of the sound [p t k b d g], but especially [t], in many contexts. In all varieties of English, fricatives like these arise in speech that is often described as ‘fast’ or ‘casual’, though perhaps a more accurate description would be ‘ordinary’. What is special about Irish and Liverpool English is that these are normal productions of ‘plosives’.