Some experts of the opinion that after nearly a century of broadcasting--commercial radio is over 90 years old, by the bye--that regional differences in the American language are disappearing. Not true! At least not yet. That's because most children -- who have the structure of the entire English language in their heads by age five(!) learn to talk primarily from their mothers, fathers, and their siblings, with reinforcements of the prevailing regional accent acquired on the school playground.
Way back in linguistics class (so many decades ago that I've lost count) we were taught simple formulae by which we could, like Prof. Henry Higgins, tell where a person hailed from. For instance, when you say "dog" and "log", do they rhyme? In my state alone, there are huge variations in the pronunciations of various words, the short "a" vowel, for instance, flattening the farther west one travels. Speakers in the Northern parts of the state have a bit of a Canadian lilt in their speech, and those of us on the counties bordering Massachusetts have some of their well-known characteristics, especially in the pronunciation of "r," making it sound vaguely like an "ah" or dropping it entirely when it ends a word and adding an "r" when the word ends in a vowel. For instance, the word "law" sounds like "lore" when somebody from Boston says it.
New York City has thousands of different phonemes, such as the famous "Bronx" and "Brooklyn" accents and the inimitable speech idiosyncracies that come from "Long Guyland." Just across the river, Jerseyites sound different from New Yorkers, and you don't even want to try to describe the accents from Pennsylvania. They have funny ways of saying "pin" and "pen" and so on. To this day I swear a local TV sports reporter hails from the Keystone State because his speech patterns show that he could never have come from anywhere else. For instance, several years back when a certain(now retired) NY Yankee was having throwing problems, the sportscaster had a unique way of saying the player's name. He pronounced "Chuck Knoblock" in a way that made him sound like Stan on "South Park."
There are few perfect speakers of English in this lovely land, yours fooly among those who miserably fall short. Not even our past Presidents have been as exemplary as we might have liked them to be. Hence, the oft-cited mispronunciation of "nuclear," which should be three syllables-- "NU-klee-IRR." (Frightening, no matter how you pronounce it.)
Even the aforementioned national broadcasters aren't perfect. I have yet heard anyone on the air say the words "calm," "luxury" or "February" right. Good thing I'm losing my hearing, because I don't know how much longer I can stand hearing somebody on TV pronounce the "t" in "often." We know enough that the "t" is silent in "listen" and "hasten," so why do we say "of-Ten"? Maybe it's a case of overcorrection, a misguided worry that it sounds like dropping the "-ng" off a participle, the way politicians do in order to seem folksy while campaigning.
Evidently Americans are self-conscious about their regional accents. Back in the late seventies and early eighties it was trendy for bosses to hire receptionists and secretaries with British accents, in the attempt to bring some class into the office. And recently there have developed cottage industries in which speech coaches try to help young executives on the career path "de-regionalize" their speaking patterns.
There are other verbal gaffes to which we Americans are susceptible. Our grammar is atrocious. (Cf. David Foster Wallace's essay on the topic in his essay collection, Consider the Lobster.)
Our biggest flaw, to me, is that we aren't expressive enough, as explained in Arthur Plotnik's fine little book, The Elements of Expression. For instance, a manager might describe one of his team members as "A great hitter, a great fielder, and a great human being." In a culture which prides itself on its "level-playing field" it's difficult to wrap our minds around expressive superlatives. That's why we describe everything we like as "awesome," and tell one another to "have a nice day."

