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0.5.10 Soundex English word-sounding Algorithm

M. K. Odell and R. C. Russell patented the Soundex phonetic comparison system in 1918 and 1922. Soundex coding takes an English word and produces a four digit representation of the word designed to match the phonetic pronunciation of the word. It is normally used for ``fuzzy''     searches where a close match may be desired. For example, to come up with alternative possibilities for a misspelled word some spelling checker programs generate a Soundex code for the misspelled word and then suggest other words with the same Soundex value. Additionally Soundex codes are often used on surnames which are difficult to spell.

The creation of a Soundex code is a pretty simple operation. The first step is to remove all non-English letters or symbols. In the case of accented vowels, simply remove the accents. Any hyphens, spaces, etc... also. In addition, remove all H's and W's unless they are the initial letter in the word. Next, take the first letter in the word and make it the first letter of the Soundex code. For each remaining letter in the word, translate it to a number with the table below and concatenate the numbers, preserving order, on to the Soundex value.

           A, E, I, O, U, Y = 0
                 B, F, P, V = 1
     C, G, J, K, Q, S, X, Z = 2
                       D, T = 3
                          L = 4
                       M, N = 5
                          R = 6

Now, combine any double numbers into a single instance of that number. Further, if the first number in the Soundex value is the same as the code number for the initial letter, delete the first number. Now, remove all zeros from the Soundex string. Finally, return the first four characters of the end product as the Soundex encoding. If there are less than four characters to be returned, concatenate enough zeros to make the length four.