From: http://www.pbs.org/speak/speech/beastly/
Often AWF-in or AHF-in. Do not pronounce the t.
Before I give you my two cents on the t in often, let’s take a look at what various authorities have said about it since the late 18th century.
John Walker (1791), whose Critical Pronouncing Dictionary was one of the most respected and popular references both in England and America well into the 19th century, declared that “in often and soften the t is silent.”
“The sounding of the t,” proclaims the legendary H.W. Fowler in Modern English Usage (1926), “which as the OED says is ‘not recognized by the dictionaries,’ is practised by two oddly consorted classes—the academic speakers who affect a more precise enunciation than their neighbours…& the uneasy half-literates who like to prove that they can spell….”
“The t in glisten is silent, even as it is in castle and often,” says Frank H. Vizetelly (1929), editor of Funk & Wagnalls New Standard (1913), “yet one occasionally hears pedants and provincials pronounce them [GLIS-ten] and [AWF-ten]. No pronouncing dictionary with a reputation to lose ever sounds the t in these words.”
“You don’t want a t in here any more than in soften,” advises Alfred H. Holt (1937).
Webster 2 (1934), which sanctions only AWF-in, notes that “the pronunciation [AWF-tin], until recently generally considered as more or less illiterate, is not uncommon among the educated in some sections, and is often used in singing.”
According to Random House II (1987),
OFTEN was pronounced with a t- sound until the 17th century, when a pronunciation without the (t) came to predominate in the speech of the educated, in both North America and Great Britain, and the earlier pronunciation fell into disfavor. Common use of a spelling pronunciation has since restored the (t) for many speakers, and today [AWF-in] and [AWF-tin]…exist side by side. Although it is still sometimes criticized, OFTEN with a (t) is now so widely heard from educated speakers that it has become fully standard once again.
“Nowadays,” says R.W. Burchfield (1996), editor of the OED 2 (1989), “many standard speakers use both [AWF-in] and [AWF-tin], but the former pronunciation is the more common of the two.
What is going on here? After two hundred years of censure, has the t in often scratched and clawed its way back into acceptability? I would caution those who might be consoled by the comments of Random House II and Burchfield to heed the admonitions of the past and avoid pronouncing the t. Current dictionaries, including Random House II, do not give priority to AWF-tin, and it is much less common in educated speech and far more often disapproved of by cultivated speakers—particularly teachers of English, drama, and speech—than Random House II makes it appear. In 1932 the English lexicographer Henry Cecil Wyld called AWF-tin “vulgar” and “sham-refined,” and today the bad odor of class-conscious affectation still clings to it as persistently as ever. As if that were not enough, analogy is entirely unsupportive: no one pronounces the t in soften, listen, fasten, moisten, hasten, chaste, christen, and Christmas—so, once and for all, let’s do away with the eccentric AWF-tin.