The importance of accent
Every speaker of English has a particular system of his or her own, known by linguists as that individual's idiolect. However, considering language only at the idiolectal level might produce extremely thorough and detailed descriptions, but would give rather little insight into why individuals speak in the way they do. To understand this, we must identify higher-level groupings, and investigate geographical and social accents. That is to say, individuals adopt a particular mode of speech (or more accurately, move along a continuum of modes of speech) depending on who they want to identify with, who they are talking to, and what impression they want to make. Not all these ‘decisions’ are conscious, of course. Small children learn to speak as their immediate family members do; but quite soon, the peer group at school (even nursery) becomes at least equally important; and later, older children, then television presenters, actors or sporting heroes may become role models, leading to modifications in accent. Consequently, age-related differences appear in all varieties; some will be transient, as a particular TV show falls out of fashion and the words or pronunciations borrowed from it disappear; others will become entrenched in young people's language, and may persist into adulthood, becoming entirely standard forms for the next generation.
This flexibility, and the associated facts of variation and gradual change, mean that phonologists face a Catch-22 situation. On the one hand, describing idiolects will give seriously limited information, since it will not reveal the groups an individual belongs to, or the dynamics of those groups. On the other hand, we must take care that the groups are not described at too abstract a level. Any description of ‘an accent’ is necessarily an idealisation, since no two speakers will use precisely the same system in precisely the same way: our physical idiosyncracies, different backgrounds, and different preferences and aspirations will see to that. Nonetheless, two speakers of, say, Scottish Standard English, or New Zealand English, will have a common core of features, which allows them to be grouped together by speakers of the same accent, by speakers of other accents, and by phonologists. Not everyone is equally adept at making these identifications, of course.