The Guardian has re-printed a comment from 75 years ago, about the effect of the BBC on the spoken word:

From the archive: Speech and the Wireless
Originally published on 29 December 1934
The Guardian, Tuesday 29 December 2009

Words, according to the French cynic, were given us in order that we might conceal our thoughts – but also, perhaps, in order that we might discuss the B.B.C. There are those who have suspected that it was one aim of the broadcasting system to run a sort of conversational steam-roller over the speech of this island, flattening out the local variations of accent and intonation and producing a "synthetic" English that would be quite unrecognisable as deriving from any specified shire or city.

On the question of the influence of broadcasting on the general speech of the people it is as yet exceedingly difficult to decide. There is little evidence so far of any conscious effort to imitate the speech of wireless announcers. And has anyone reported an improvement in the French or German accents of natives of this country as a result of daily opportunities to hear those tongues spoken from wireless stations abroad? One would say that, so far, the talking films, which have introduced not only the terms but the intonations of the United States, have had (but chiefly among the young) a more obvious influence on the speech of this island. Even there the effect is transitory, as one would expect it to be. After all, people remove themselves to parts of this country far distant from those in which they were born and still retain to the ends of their lives accents and tones that belong to their birthplace.

The feared "levelling" influence of "B.B.C. English" is not likely to have much effect on that intractable human tendency. Where the B.B.C. may influence and possibly intends to influence the speech of our time is on the smaller but decidedly important point of disputed pronunciations. But even there and when the points are most hotly disputed the B.B.C. is seldom an innovator. The universal ability to read has had a far greater effect. It has given us pronunciations derived from the eye instead of the ear and the usages of tradition.

The curious thing is that broadcasting, which, as the new and farspread custodian of the spoken word, might have acted as a restraint on such changes from traditional forms, has tended rather to endorse them. When B.B.C. advisory committees recommend that announcers say "kon-dew-it" instead of "kun-dit" for the word which is spelled "conduit", they are welcoming an arrival which many still regard as a vulgarism and which has plainly arisen from the use of the eye instead of the ear. It would, of course, be flying in the face of history to suggest that pronunciations should be changeless and sacrosanct: if they were, we should still be saying "laylock" for "lilac", "tay" for "tea", or "goolden" for "golden". The language moves, and it is rash, and ultimately ignorant, to resist its changes. What is needed is a nicely balanced appreciation of the respective claims of tradition and innovation; we must be ready to move, but not, it may be suggested, merely because hasty readers have decided that a word ought to be pronounced the way it is spelt. That would be a way of outflanking the "reformed spelling" problem, but it is not to be recommended.

Caution is desirable and tradition should be considered – otherwise we shall have the "p" emerging in "cupboard", or the "b" in "plumber", even as some already sound a quite unnecessary "t" in "often". Such visual pronunciation needs watching and, generally, resisting. If the B.B.C. will essay a balancing feat between oral tradition and innovation, and do it deftly, it may, by the force of example, exercise a most important influence on the progress of the English tongue.