Somewhere along about the Third Grade we discovered that certain words are not pronounced at all the way they should be from their spellings. Remember PNEUMONIA with a silent P?
Logological research in this area appears to have been restricted to single letters. A list of 26 words containing the 26 silent letters and a corresponding list in which a letter sound appears without the letter was printed in the August 1970 issue of Word Ways (both lists were originally compiled by Dmitri Borgmann).
Beaman, Ralph G.
Word Ways: Vol. 5
, Article 8.
Available at: http://digitalcommons.butler.edu/wordways/vol5/iss3/8