Metaphone
Metaphone是一个语音算法，主要是用在英语单字或是辞汇发音的标引。Metaphone是由飞利浦、罗伦斯利用Soundex的缺陷来改善的演算法。此演算法是利用较大的英语发音规则，所以比Soundex更为精准。Metaphone也可作为内建式的工具，在PHP就有相关工具。后来原作者制作新版本的演算法“Double metaphone”，比原本的算法还更加精准。该演算法会转换相似的发音。
转换规则
B ----> B unless at the end of word after "m", as in "dumb", "McComb"
C ----> X (sh) if "-cia-" or "-ch-"
S if "-ci-", "-ce-", or "-cy-"
SILENT if "-sci-", "-sce-", or "-scy-"
K otherwise, including in "-sch-"
D ----> J if in "-dge-", "-dgy-", or "-dgi-"
T otherwise
F ----> F
G ----> SILENT if in "-gh-" and not at end or before a vowel
in "-gn" or "-gned"
in "-dge-" etc., as in above rule
J if before "i", or "e", or "y" if not double "gg"
K otherwise
H ----> SILENT if after vowel and no vowel follows
or after "-ch-", "-sh-", "-ph-", "-th-", "-gh-"
H otherwise
J ----> J
K ----> SILENT if after "c"
K otherwise
L ----> L
M ----> M
N ----> N
P ----> F if before "h"
P otherwise
Q ----> K
R ----> R
S ----> X (sh) if before "h" or in "-sio-" or "-sia-"
S otherwise
T ----> X (sh) if "-tia-" or "-tio-"
0 (th) if before "h"
silent if in "-tch-"
T otherwise
V ----> F
W ----> SILENT if not followed by a vowel
W if followed by a vowel
X ----> KS
Y ----> SILENT if not followed by a vowel
Y if followed by a vowel
Z ----> S