A reader commenting on Wile vs While wrote:
Modern speakers and writers have a problem with “W” words such as “while” and “wile” (another example: “whale,” “wale,” and “wail”) because there is no longer a distinction made between the way “wh” and “w” are pronounced.
Not all American speakers distinguish between the sounds of whine and wine, but many still do. There are advantages to teaching the distinction, even in regions where the difference has been lost in the local dialect.
Wh represents the sound one makes when blowing out a candle: [wh].
The number of English words that begin with wh is not large, and even speakers who distinguish between the initial sounds of Wales and whales do not pronounce wh as [wh] in every word that begins with the wh spelling.
For speakers of dialects that still distinguish between the pronunciation of which and witch, the following words begin with the aspirated sound [wh]:
In the following words, the spelling wh represents the sound [h].
What linguists call the “wine-whine merger” is no doubt destined to prevail in the United States. Nevertheless, teaching the aspirated sound of wh is an aid to spelling mastery.