Daitch–Mokotoff Soundex (D–M Soundex) is a phonetic algorithm invented in 1985 by Jewish genealogists Gary Mokotoff and Randy Daitch. It is a refinement of the Russell and American Soundex algorithms designed to allow greater accuracy in matching of Slavic and Yiddish surnames with similar pronunciation but differences in spelling.
Daitch–Mokotoff Soundex is sometimes referred to as "Jewish Soundex" and "Eastern European Soundex", although the authors discourage use of these nicknames for the algorithm because the algorithm itself is independent of the fact the motivation for creating the new system was the poor results of predecessor systems when dealing with Slavic and Yiddish surnames.
Improvements over the older Soundex algorithms include:
- Coded names are six digits long, resulting in greater search precision (traditional Soundex uses four characters)
- The initial character of the name is coded.
- Several rules in the algorithm encode multiple character n-grams as single digits (American and Russell Soundex do not handle multi-character n-grams)
- Multiple possible encodings can be returned for a single name (traditional Soundex returns only one encoding, even if the spelling of a name could potentially have multiple pronunciations)
|Surname||American Soundex||D–M Soundex|
|Jackson||J250||154600, 454600, 145460, 445460|
|Jackson-Jackson||J252||154664, 454664, 145466, 445466, 154646, 454646, 145464, 445464|
Beider–Morse Phonetic Name Matching Algorithm
To address the large number of false positive results generated by the D–M Soundex, Stephen P. Morse and Alexander Beider created the Beider–Morse Phonetic Name Matching algorithm. This new algorithm cuts down on false positives at the expense of some false negatives. A number of sites are offering the B–M soundex in addition to the D-M soundex.
- Beider–Morse Phonetic Matching: An Alternative to Soundex with Fewer False Hits - copy of Avotaynu: the International Review of Jewish Genealogy (Summer 2008)
- Nu? What's New? Volume 9, Number 22 Gary Mokotoff, Editor - The E-zine of Jewish Genealogy From Avotaynu
- Mokotoff, Gary. "Soundexing and Genealogy." Describes the history and the motivations behind D–M Soundex.
- JewishGen. "Soundex Coding." Describes both Russel and D–M Soundex.
- Coles, Michael. "SQL 2000 DBA Toolkit, Part 3: Phonetic Matching" SQL Server-based implementation of the D–M Soundex algorithm w/source.