We hear what we want to hear and what we expect to hear.
What am I referring to? Not just the meaning of what is said (semantics: matters especially when we try to recall events – we are more prone to remember that something was said which matches our beliefs and expectations, even if that may not be true), but also pronunciation (phonology and prosody) which I’m gonna go on about here in more detail.
Before I moved to New Zealand for a year, everyone told me the kiwi accent was very different, notably due to varying vowels (a funny example (possible exaggerated) is the pronunciation of deck as dick in this video). Indeed, it took a few weeks to get used to the accent. By the end of the year, however, I didn’t even notice anymore whether someone had a kiwi accent or spoke some kind of English I had been used to from the UK. To realise what accent was spoken I would have to “consciously” listen and even then I found it harder to figure out the accent than before I was used to it. It seemed to me like, once I was very familiar with an accent, my brain would simply interpret it as English. Any less familiar accents would be ‘harder’ to understand i.e. not be processed as quickly as the very familiar Englishes, and thus also receive (unknown) labels more easily. So I came up with the following diagram representing how accents might be stored differently in our brains:
With familiar I mean the level of exposure
With known I mean you know of the accent (media, some acquaintances…) without necessarily being exposed to it much
If English is your native language, your own accent will largely depend on your parents’ dialect and the dialect spoken in your surroundings. If your native language isn’t English, your English accent will be greatly affected by your mother tongue’s phonetic inventory and phonotactics. Either way though, your English (or other regularly spoken language(s)) will change throughout your life and your pronunciation will be particularly affected by the different accents you’ll be exposed to. I believe that your own accent will be a mixture of the Englishes stored in your ‘blue box’. To my knowledge, the way accents are stored in our brains is yet ‘unknown’, so this is just the way I think it could work. Do comment if you have another hypothesis or know of any, and do reference me if you go somewhere with my theory ;)