Patent Publication Number: US-2023153336-A1

Title: System and method for recommendation of terms, including recommendation of search terms in a search system

Description:
RELATED APPLICATION(S) 
     This application is a continuation of, and claims a benefit of priority under 35 U.S.C. 120 of, U.S. patent application Ser. No. 16/645,352 filed Mar. 6, 2020, entitled “SYSTEM AND METHOD FOR RECOMMENDATION OF TERMS, INCLUDING RECOMMENDATION OF SEARCH TERMS IN A SEARCH SYSTEM,” which is a national stage application of and claims the benefit of priority to International Application No. PCT/IB2018/056642 filed Aug. 30, 2018, entitled “SYSTEM AND METHOD FOR RECOMMENDATION OF TERMS, INCLUDING RECOMMENDATION OF SEARCH TERMS IN A SEARCH SYSTEM,” which claims a benefit of priority under 35 U.S.C. 119 to U.S. Provisional Patent Application No. 62/556,132, filed Sep. 8, 2017, entitled “SYSTEM AND METHOD FOR RECOMMENDATION OF TERMS, INCLUDING RECOMMENDATION OF SEARCH TERMS IN A SEARCH SYSTEM,” which are hereby incorporated herein for all purposes. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to search systems. More particularly, this disclosure relates to embodiments of search systems capable of suggesting alternative search terms. Even more specifically, this disclosure relates to embodiments of search systems capable of suggesting alternative search terms based on the sounds of such search terms. 
     BACKGROUND 
     A search system (often referred to as a search engine) is a computer system used to index electronically stored information and search the indexed electronic information to return electronically stored information responsive to a search. In a conventional search engine, a user submits a query and the search engine selects a set of results from the corpus based on the terms of the search query. The terms of search queries usually specify words, phrases, logical relationships, metadata fields to be searched, synonyms, stemming variations, etc. 
     In such a conventional search engine, search index may specify which documents contain which terms. When a user submits a search, the search terms may be evaluated against the search index to determine results (e.g., documents of the corpus) responsive to the search. Generally, there are two basic methods for selecting a set of results from a corpus based on a search query. In the first method, a document that meets the explicit search terms of the search query will be selected as responsive. In the second method, for some types of search applications, the set of results selected is constrained (or further constrained) by a relevance measure. In particular, results selected by evaluating a search query as an explicit query are further scored and ordered by some criteria, and only the highest results are selected. 
     One problem that occurs in conjunction with the use of these types of search engines is that a searching user may enter a search term that may not necessarily be the keyword that will obtain a desired search result. For example, the user may misspell a search term. Accordingly, some search systems may provide suggestions to a searching user for additional, different or substitute search terms based on the search terms the user enters. By allowing a user to select additional or substitute terms, higher quality (e.g., more relevant or responsive) search results may be returned in response to a search. 
     Typically, these search systems may utilize a conventional spell checker to determine if the user has misspelled any search terms and provide correctly spelled words as search term suggestions. Edit distance algorithms may also be used to provide search term suggestions, whereby terms that are less than a certain edit distance from a search term may be provided as suggestions to a user. While this approach accounts for some misspellings, the use of edit distance is also problematic, at least because edit distance isn&#39;t necessarily reflective of terms that may have similar sounds or pronunciation. Thus, like the user of other types of spell checking algorithms, the use of edit distance may not serve to address the certain instances of incorrectly spelled or utilized terms. Moreover, the edit limit distance that may be effectively utilized is usually quite small (e.g., usually less than two), as the use of larger edit distances may adversely affect the performance of such algorithms (e.g., the search for similar terms becomes longer as the edit distance increases). 
     What is desired, then, are search systems which can provide high quality suggestions for alternative search terms to a searching user. 
     SUMMARY 
     To that end, among others, attention is now directed to embodiments of systems and methods for providing search term suggestions in a search system as disclosed herein. Embodiments as disclosed may utilize the sound of an original search term to locate candidate terms based on the sound of the candidate terms and the frequency of appearance of the candidate terms in the corpus of documents being searched. A set of search term suggestions can then be determined from the candidate terms and returned to the user as search term suggestions for the original search term. 
     In particular, in certain embodiments, the frequency of the original search term may be utilized as a baseline such that all search term suggestions returned may occur more frequently than the original search term in the corpus of documents being searched. In this manner, it can be assured that not only are similar sounding words returned as suggestions but, additionally, that the search terms suggested are more likely to be terms desired by the user. As such, embodiments may offer the advantage of providing relevant, high quality search term suggestions that may account both for misspelled words and the unintentional use of homophones by the searching user (e.g., of more frequently used or desired search terms). 
     In one embodiment, a set of candidate terms may be generated using each of a set of different phonetic encoder modules, each phonetic encoder module employing a different phonetic encoder. A phonetic encoder module thus may receive a term (e.g., an original search term), encode the term to produce a corresponding code, and return a set of candidate terms associated with the corresponding code. To assemble the set of candidate terms, one or more phonetic encoder modules may be used to generate a corresponding set of candidate terms based on the sound code of the original search term. Candidate terms having a frequency (of appearance in the corpus) less than the original search term may be discarded. The set of candidate terms comprises the set of candidate terms returned by each phonetic encoder module. 
     In some embodiments, these phonetic encoder modules may be ordered such that they may be evaluated according to the order to determine the set of candidate terms generated by each phonetic encoder module until a threshold number of candidate terms is obtained. In another embodiment, an initial phonetic encoder module (e.g., employing an Exact Match phonetic encoder) may be utilized to determine a set of candidate terms. If no candidate terms are returned by the initial phonetic encoder module (or less than a candidate threshold number of candidates are returned), one or more, or all of the other phonetic encoder modules may be utilized to generate the set of candidate search terms. 
     Once the set of candidate terms is generated using the phonetic encoder modules, in one embodiment, each of the candidate terms may be ranked (also referred to as scored, ordered or sorted) based on the frequency (of appearance in the corpus) of the candidate term and the sound distance of the candidate term from the original search term. In one embodiment, the sound distance may be an edit distance (e.g., a Levenshtein distance) of the phoneme sequence between the original search term and the candidate search term. In other words, the minimum number of operations required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. Additionally, the sound distance may be weighted according to the type of operations or steps required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. The weights may be greater for relatively big operations (e.g., substituting a vowel with a consonant, substituting a consonant with a different consonant, inserting or deleting a consonant) and lesser for relatively smaller magnitude operations (e.g., substituting a vowel with another vowel, substituting a consonant with a similar consonant, inserting or deleting a vowel). The greater weights may be, for example, approximately twice the lesser weights. The score or sorting of the candidate terms can be determined based on the frequency or sound distance. For example, the candidate terms may be ranked according to sound distance (with the least sound distance having a higher ranking) and candidate terms with the same sound distance ranked relative to one another according to frequency (of appearance in the corpus), with a candidate term with greater frequency ranking higher than a candidate term with a lesser frequency. A formula may be used to consider both the frequency and sound distance for each candidate term to generate a score for each candidate term and the candidate terms ranked according to their score. Other methods of ranking the candidate search terms are also possible. A set of candidate search terms may then be selected based on their ranking or ordering and returned to the user as search term suggestions. 
     In certain embodiments, to facilitate the searching of candidate search terms, a separate sound index may be maintained. The sound index may include, for each term of the corpus, an entry for that term for each sound code generated by each of the sound encoder modules of the search system. The sound code is associated with the search term itself and a frequency count indicating the number of appearances of the term in the corpus of documents associated with the search system. Each entry in the sound index may thus comprise a term that appears in the corpus, a code (e.g., a code for the term generated by a sound encoder module utilized by the search system) and a frequency for the term. Each entry could be stored, for example, as a triple (&lt;code, frequency, term&gt;) such that the entries in the sound index are ordered first by code, then by frequency. The sound index could be maintained in a triple store or the like. 
     Accordingly, when a phonetic encoder module is generating a set of candidates, it may search this sound index based on the sound code that the phonetic encoder module generated for the original search term and the frequency of the original search term (which may also be obtained from the sound index if desired by searching on the original search term). For example, a prefix query can be made on the code for the original search term plus the frequency of the original search term. The set of candidate terms generated by the phonetic encoder may be the set of terms that have the identical code and a frequency greater than the frequency of the original search term. As the candidate terms are stored sequentially (e.g., according to an order based on codes or frequency) in the sound index, they may be quickly determined and returned by the phonetic encoder. 
     To generate such a sound index, in one embodiment, when a document is indexed by a search system when the indexer tokenizes the document to obtain the terms to be indexed, it can be determined if the term is currently in the sound index (e.g., by searching on the term in the sound index). If the term has previously been indexed, the frequency counts associated with each entry in the sound index associated with that term may be incremented. If, however, the term is not in the sound index, for each phonetic encoder module utilized by the search system, that phonetic encoder of the module may be utilized to generate a corresponding code for the term. An entry in the sound index for that code, a frequency of 1 and the term may then be created. In this manner, new entries in the sound index corresponding to that term and the codes generated by each sound encoder module of the search system may be created. 
     In one particular embodiment, a system for providing suggestions of terms may include a data store storing a sound index and a corpus of documents, and a processor. A non-transitory computer-readable medium stores instructions for determining a frequency of appearance of the original term in the corpus of documents and determining a set of candidate terms. Each candidate term may have a sound code that is the same as a sound code for the original term and may appear more frequently in the corpus of document than the frequency of the original term. The set of candidate terms can be ranked and a number of the candidate terms selected based on the ranking. The selected candidate terms may be provided as suggestions for the original term. 
     In a similar embodiment, determining a set of candidate terms may include generating the sound code for the original search term according to a phonetic encoder and searching the sound index based on the sound code and the frequency of the original term to determine the set of candidate terms. Each of the set of candidate terms may have the same sound code as the original term and a frequency greater than the frequency of the original term. These phonetic encoders may be an Exact Match, Metaphone, Double Metaphone, Soundex, Caverphone or Daitch-Mokotoff encoder. 
     In certain embodiments, the set of candidate terms are ranked based on a sound edit distance and the sound edit distance for a candidate term is based on a number of operations required to transform a first phoneme sequence of the candidate term to a second phoneme sequence of the original term. The sound edit distance can be weighted based on a type of the operations required to transform the first phoneme sequence to the second phoneme sequence. The candidates can be ranked based on the frequency of each candidate term. 
     In some embodiments, a document in the corpus may be indexed to update the sound index. Indexing a document may include determining a set of terms of the document and determining if each term is in the sound index. If a term is in the sound index, a frequency associated with each entry in the sound index associated with the term may be updated. If a term is not in the sound index, a code for the term can be generated using the phonetic encoder and a new entry in the sound index corresponding to the code, the term and a frequency of one created. 
     These, and other, aspects of the invention will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. The following description, while indicating various embodiments of the invention and numerous specific details thereof, is given by way of illustration and not of limitation. Many substitutions, modifications, additions or rearrangements may be made within the scope of the invention, and the invention includes all such substitutions, modifications, additions or rearrangements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings accompanying and forming part of this specification are included to depict certain aspects of the invention. A clearer impression of the invention, and of the components and operation of systems provided with the invention, will become more readily apparent by referring to the exemplary, and therefore nonlimiting, embodiments illustrated in the drawings, wherein identical reference numerals designate the same components. Note that the features illustrated in the drawings are not necessarily drawn to scale. 
         FIG.  1    is a block diagram depicting a computing environment in which one embodiment of a search system can be implemented. 
         FIG.  2    is a block diagram depicting one embodiment of a search engine. 
         FIG.  3 A  is a block diagram depicting one embodiment of a search engine having a term recommender. 
         FIG.  3 B  is a block diagram depicting one embodiment of a search engine having a term recommender deployed in a cloud based computing platform. 
         FIG.  4    is a flow diagram depicting one embodiment of a method for indexing. 
         FIG.  5    is a flow diagram depicting one embodiment of a method for providing search term suggestions. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosure and various features and advantageous details thereof are explained more fully with reference to the exemplary, and therefore non-limiting, embodiments illustrated in the accompanying drawings and detailed in the following description. It should be understood, however, that the detailed description and the specific examples, while indicating the preferred embodiments, are given by way of illustration only and not by way of limitation. Descriptions of known programming techniques, computer software, hardware, operating platforms and protocols may be omitted so as not to unnecessarily obscure the disclosure in detail. Various substitutions, modifications, additions and/or rearrangements within the spirit and/or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure. 
     Before describing embodiments in more detail, some additional context may be useful. A search system (often referred to as a search engine) is a computer system used to index electronically stored information (referred to as a corpus) and search the indexed electronic information to return electronically stored information responsive to a search. Items of electronic information that form the corpus may be referred to interchangeably as (electronic) documents, files, objects, items, content, etc. and may include objects such as files of almost any type including documents for various editing applications, emails, workflows, etc. In a conventional search engine, a user submits a query and the search engine selects a set of results from the corpus based on the terms of the search query. The terms of search queries usually specify words, phrases, logical relationships, metadata fields to be searched, synonyms, stemming variations, etc. 
     In a conventional search engine, when indexing a document, a tokenizer converts the document into discrete tokens (or terms) that are indexed by the search engine in a search index. A search index (sometimes just referred to as an index), such as an inverted index or the like, may specify which documents contain which terms. A tokenizer is a software tool programmed to perform tokenization. Tokenization refers to the process of breaking up a string of text into words, phrases, symbols, or other meaningful elements called tokens (or terms). A token, in this context, refers to a word or an atomic data element that cannot be parsed any further. When a user submits a search, the search terms may be evaluated against the search index to determine results (e.g., documents of the corpus) responsive to the search. 
     Generally, there are two basic methods for selecting a set of results from a corpus based on a search query. In the first method, a document that meets the explicit search terms of the search query will be selected as responsive. Only items of the corpus that meet the explicit requirements of the search terms are selected and presented. In the second method, for some types of search applications, the set of results selected is constrained (or further constrained) by a relevance measure. In particular, results selected by evaluating a search query as an explicit query are further scored and ordered by some criteria, and only the highest results are selected. 
     One problem that occurs in conjunction with the use of these types of search engines is that a searching user may enter a search term (often referred to as a keyword) that may not necessarily be the keyword that will obtain a desired search result. For example, the user may misspell a search term. Or, a user may enter a homophone of the actual word he wishes to search for (e.g., the user may desire to search for “whale” but may enter “wail”). Accordingly, some search systems may provide suggestions to a searching user for additional, different or substitute search terms based on the search terms the user enters. By allowing a user to select additional or substitute terms, higher quality (e.g., more relevant or responsive) search results may be returned in response to a search. 
     Typically, these search systems may utilize a conventional spell checker to determine if the user has misspelled any search terms and provide correctly spelled words as search term suggestions. The use of a spell checker cannot, however, address the situation in which a user has used a homophone of the search term that is actually desired. To account for these instances, some search systems may employ a phonetic algorithm to attempt to locate similar sounding words to a search term and provide these similar sounding words to the user as search term suggestions. These phonetic algorithms may use a phonetic encoder to encode a term (e.g., extract a code for a term based on the sounds of the word) and search a set of terms for terms with similar codes to generate a set of similar search terms that may be provided as suggestions. The use of these phonetic algorithms is problematic for a few reasons. Use of certain phonetic algorithms, such as a sound dictionary based algorithm, may only return terms with the exact same pronunciation and may thus be too restrictive. Other phonetic algorithms that employ phonetic encoders may return too few or too many results (e.g., 100 or more) to be useful in this context. This variability may exist for a single algorithm depending on the term, whereby one algorithm returns too few results for one term and too many for another term. Moreover, these phonetic algorithms may only operate effectively using the first few phonemes of a term, which may adversely impact their efficacy with respect to longer search terms. 
     As an example, here are examples of the codes produced for the word “bark” by different phonetic algorithms, along with words with that may produce the same code: 
     
       
         
           
               
               
               
             
               
                   
               
               
                 Algorithm 
                 code 
                 Words 
               
               
                   
               
             
            
               
                 Exact match 
                 b, aa, r, k 
                 bark, barq, barc 
               
               
                 Metaphone 
                 brk 
                 brick, brook, bourke, brake, brokaw, brugge, baroque, braga,  
               
               
                   
                   
                 barack, bark, borg . . .  
               
               
                 Double  
                 prk 
                 bourke, brook, bark, prage, bourque, preach, burgh, paraguay,  
               
               
                 Metaphone 
                   
                 brock, brooke, break, parague, . . .  
               
               
                 Soundex 
                 b620 
                 bureaus, bourke, broke, buyers, brass, brugge, borg, burj,  
               
               
                   
                   
                 baroque, break, bark, . . .  
               
               
                 Caverphone 
                 pk1111 
                 big, bag, pack, jpg, park, bark, pork, boogie, butcher, berger,  
               
               
                   
                   
                 berg, pak, peach, . . .  
               
               
                 Daitch- 
                 795,000.00 
                 wreck, prague, brake, burk, baroque, borough, bark, broke,  
               
               
                 Mokotoff 
                   
                 perugia, brook, . . . 
               
               
                   
               
            
           
         
       
     
     Edit distance algorithms may also be used to provide search term suggestions, whereby terms that are less than a certain edit distance from a search term may be provided as suggestions to a user. Edit distance is a minimum number of operations (or alterations to the term) that may be needed to transform one term to another term. Thus, terms which are less than a certain edit distance from an original search term may be provided as suggestions to a searching user. While this approach accounts for some misspellings, the use of edit distance is also problematic, at least because edit distance isn&#39;t necessarily reflective of terms that may have similar sounds or pronunciation. Thus, like the user of other types of spell checking algorithms, the use of edit distance may not serve to address the use of homophones by a user. Moreover, the edit limit distance that may be effectively utilized is usually quite small (e.g., usually less than two), as the use of larger edit distances may adversely affect the performance of such algorithms (e.g., the search for similar terms becomes longer as the edit distance increases). 
     What is desired, then, are search systems which can provide high quality suggestions for alternative search terms to a searching user. 
     To that end, among others, attention is now directed to embodiments of systems and methods for providing search term suggestions in a search system as disclosed herein. Embodiments as disclosed may utilize the sound of an original search term to locate candidate terms based on the sound of the candidate terms and the frequency of appearance of the candidate terms in the corpus of documents being searched. A set of search term suggestions can then be determined from the candidate terms and returned to the user as search term suggestions for the original search term. 
     In particular, in certain embodiments, the frequency of the original search term may be utilized as a baseline such that all search term suggestions returned may occur more frequently than the original search term in the corpus of documents being searched. In this manner, it can be assured that not only are similar sounding words returned as suggestions but, additionally, that the search terms suggested are more likely to be terms desired by the user. As such, embodiments may offer the advantage of providing relevant, high quality search term suggestions that may account both for misspelled words and the unintentional use of homophones by the searching user (e.g., of more frequently used or desired search terms). 
     In one embodiment, a set of candidate terms may be generated using each of a set of different phonetic encoder modules, each phonetic encoder module employing a different phonetic encoder. A phonetic encoder module thus may receive a term (e.g., an original search term), encode the term to produce a corresponding code, and return a set of candidate terms associated with the corresponding code. To assemble the set of candidate terms, one or more phonetic encoder modules may be used to generate a corresponding set of candidate terms based on the sound code of the original search term. Candidate terms having a frequency (of appearance in the corpus) less than the original search term may be discarded. The set of candidate terms comprises the set of candidate terms returned by each phonetic encoder module. 
     In some embodiments, these phonetic encoder modules may be ordered such that they may be evaluated according to the order to determine the set of candidate terms generated by each phonetic encoder module until a threshold number of candidate terms is obtained. In another embodiment, an initial phonetic encoder module (e.g., employing an Exact Match phonetic encoder) may be utilized to determine a set of candidate terms. If no candidate terms are returned by the initial phonetic encoder module (or less than a candidate threshold number of candidates are returned), one or more, or all, of the other phonetic encoder modules may be utilized to generate the set of candidate search terms. 
     Once the set of candidate terms is generated using the phonetic encoder modules, in one embodiment, each of the candidate terms may be ranked (also referred to as scored, ordered, or sorted) based on the frequency (of appearance in the corpus) of the candidate term and the sound distance of the candidate term from the original search term. In one embodiment, the sound distance may be an edit distance (e.g., a Levenshtein distance) of the phoneme sequence between the original search term and the candidate search term. 
     In other words, in one embodiment, the minimum number of operations required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. Additionally, the sound distance may be weighted according to the type of operations or steps required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. The weights may be greater for relatively big operations (e.g., substituting a vowel with a consonant, substituting a consonant with a different consonant, inserting or deleting a consonant) and lesser for relatively smaller magnitude operations (e.g., substituting a vowel with another vowel, substituting a consonant with a similar consonant, inserting or deleting a vowel). The greater weights may be, for example, approximately twice the lesser weights. 
     In certain embodiments, the score or sorting of the candidate terms can be determined based on the frequency or sound distance. For example, the candidate terms may be ranked according to sound distance (with the least sound distance having a higher ranking) and candidate terms with the same sound distance ranked relative to one another according to frequency (of appearance in the corpus), with a candidate term with greater frequency ranking higher than a candidate term with a lesser frequency. A formula may be used to consider both the frequency and sound distance for each candidate term to generate a score for each candidate term and the candidate terms ranked according to their score. Other methods of ranking the candidate search terms are also possible. A set of candidate search terms may then be selected based on their ranking or ordering and returned to the user as search term suggestions. 
     In particular embodiments, a separate sound index may be maintained to facilitate the searching of candidate search terms. The sound index may include, for each term of the corpus, an entry for that term for each sound code generated by each of the sound encoder modules of the search system. The sound code is associated with the search term itself and a frequency count indicating the number of appearances of the term in the corpus of documents associated with the search system. Each entry in the sound index may thus comprise a term that appears in the corpus, a code (e.g., a code for the term generated by a sound encoder module utilized by the search system) and a frequency for the term. Each entry could be stored, for example, as a triple (&lt;code, frequency, term&gt;) such that the entries in the sound index are ordered first by code, then by frequency. The sound index could be maintained in a triple store or the like. 
     Accordingly, when a phonetic encoder module is generating a set of candidates, it may search this sound index based on the sound code that the phonetic encoder module generated for the original search term and the frequency of the original search term (which may also be obtained from the sound index if desired by searching on the original search term). For example, a prefix query can be made on the code for the original search term plus the frequency of the original search term. The set of candidate terms generated by the phonetic encoder may be the set of terms that have the identical code and a frequency greater than the frequency of the original search term. As the candidate terms are stored sequentially (e.g., according to an order based on codes or frequency) in the sound index, they may be quickly determined and returned by the phonetic encoder. The use of embodiments of this type of a sound index may therefore speed not only the searching process within the sound index, but additionally may speed the determination or selection of candidate and, in turn, speed the overall searching process of a user. 
     To generate embodiments of such a sound index, in one embodiment, when a document is indexed by a search system when the indexer tokenizes the document to obtain the terms to be indexed, it can be determined if the term is currently in the sound index (e.g., by searching on the term in the sound index). If the term has previously been indexed, the frequency counts associated with each entry in the sound index associated with that term may be incremented. If, however, the term is not in the sound index, for each phonetic encoder module utilized by the search system, that phonetic encoder of the module may be utilized to generate a corresponding code for the term. An entry in the sound index for that code, a frequency of 1 and the term may then be created. In this manner, new entries in the sound index corresponding to that term and the codes generated by each sound encoder module of the search system may be created. 
     In one particular embodiment, a system for providing suggestions of terms may include a data store storing a sound index and a corpus of documents, and a processor. A non-transitory computer-readable medium stores instructions for determining a frequency of appearance of the original term in the corpus of documents and determining a set of candidate terms. Each candidate term may have a sound code that is the same as a sound code for the original term and may appear more frequently in the corpus of document than the frequency of the original term. The set of candidate terms can be ranked and a number of the candidate terms selected based on the ranking. The selected candidate terms may be provided as suggestions for the original term. 
     In a similar embodiment, determining a set of candidate terms may include generating the sound code for the original search term according to a phonetic encoder and searching the sound index based on the sound code and the frequency of the original term to determine the set of candidate terms. Each of the set of candidate terms may have the same sound code as the original term and a frequency greater than the frequency of the original term. These phonetic encoders may be an Exact Match, Metaphone, Double Metaphone, Soundex, Caverphone or Daitch-Mokotoff encoder. 
     In certain embodiments, the set of candidate terms are ranked based on a sound edit distance and the sound edit distance for a candidate term is based on a number of operations required to transform a first phoneme sequence of the candidate term to a second phoneme sequence of the original term. The sound edit distance can be weighted based on a type of the operations required to transform the first phoneme sequence to the second phoneme sequence. The candidates can be ranked based on the frequency of each candidate term. 
     In some embodiments, a document in the corpus may be indexed to update the sound index. Indexing a document may include determining a set of terms of the document and determining if each term is in the sound index. If a term is in the sound index, a frequency associated with each entry in the sound index associated with the term may be updated. If a term is not in the sound index, a code for the term can be generated using the phonetic encoder and a new entry in the sound index corresponding to the code, the term and a frequency of one created. 
     Before describing embodiments in detail, it may be helpful to discuss an example search system in which embodiments as disclosed herein may be utilized. It will be noted at this point that while embodiments as described herein are described in conjunction with their use in search systems other embodiments may also be effectively utilized in other contexts, such as for use in spell checking when composing or editing documents in an editing application or other setting where suggestions of alternative terms may be useful, as will be understood by those of ordinary skill in the art. Thus, the description of embodiments in the context of a search system should be taken as exemplary only and not in any way as a limitation on embodiments generally. All such alternative embodiments or uses of the systems and methods described are fully contemplated herein without loss of generality. 
     Looking then at  FIG.  1   , a block diagram illustrating an example of computing environment  100  having repository  105 , search system  101 , and client computer  130  is depicted. Repository  105  may comprise a file server or database system or other storage mechanism remotely or locally accessible by search system  101 . Repository  105  may store documents  107  (e.g., objects, images, emails or other objects) that may be searchable by search system  101 . 
     In the embodiment of  FIG.  1   , search system  101  comprises a server having central processing unit (“CPU”)  112  connected to memory  114  and storage unit  118 . CPU  112  may represent a single processor, multiple processors, a processor(s) with multiple processing cores and the like. Storage unit  118  may include a non-transitory storage medium such as hard disk drives, flash memory devices, optical media and the like. Search system  101  may be connected to a data communications network. 
     Storage unit  118  stores computer executable instructions  119  and index  124 . Computer executable instructions  119  can represent one or more programs or operating system code. In one embodiment, instructions  119  are executable to provide indexer  120  and search engine  122 . Indexer  120  and search engine  122  may be portions of the same program or may be separate programs. For example, indexer  120  may be a component of a document management system while search engine  122  is a separate program that interfaces with the document management system. Furthermore, indexer  120  and search engine  122  can be implemented on different computing systems and can, themselves, be distributed. 
     Index  124  includes data used to identify documents in response to a search query and may also include text used to identify objects. In particular, in one embodiment, the index  124  may specify which documents  107  contain which terms. Index  124  can include a single index containing metadata and text, separate metadata and text indexes or other arrangements of information. While shown as a single index, index  124  may include multiple indices as will be discussed in more detail. 
     Client computer system  130  may include components similar to those of the server of search system  101 , such as CPU  138 , memory  136 , and storage  140 . Additionally, client computer system  130  may include executable instructions  132  to provide user interface  134  that allows a user to enter a search query. User interface  134  may be provided through a web browser, file system interface or other program. Thus, the user interface  134  may be provided from the search system  101  and rendered or displayed on the client computer  130 . 
     Those skilled in the art will appreciate that search system  101  shown in  FIG.  1    is merely an example of a computing system and embodiments of a search system that may be implemented using other computing systems or functionality (e.g., desktop computers, laptops, mobile computing devices or other computing devices with adequate processing and memory) including multiple computers acting together to provide a search system (e.g., a cluster of servers or other computing devices connected by a network acting together to provide the search system). Similarly, client computer  130  may include any suitable desktop computer, laptop, mobile device, server or other computing system. 
     In operation, indexer  120  may analyze documents  107  in repository  105  to determine information to be indexed in index  124 . When a document  107  is added to search system  101 , two types of information may be indexed, one or both full text and metadata. As an example, suppose document  107  being added to search system  101  is a text file, the text or content of the file is indexed as well as information about the document. In particular, a tokenizer converts the document being indexed into discrete tokens (or terms) that are used to create or update entries in index  124  to indicate which terms the document contains. Indexer  120  can send indexing instructions to search engine  122  to direct search engine  122  to add, modify, or delete data in index  124 , or may itself add, modify, or delete data in index  124 . 
     When a search query is received at search system  101 , search engine  122  determines the search terms of the search query and can utilize the information in index  124  to identify documents  107  responsive to the search query. A list or other representation of those responsive documents  107  may be provided through the interface  134 . An example search engine will now be described with reference to  FIG.  2   . 
       FIG.  2    depicts a diagrammatic representation of logical blocks for one embodiment of search engine  222 . Search engine  222  may provide indexing interface  200  that receives indexing requests (e.g., from indexer  120 ) or other source. A distributor module  210  may distribute the indexing requests to indexing engines  220  that act on the indexing requests to update index  224 . Search engine  222  may also include search interface  230  to receive queries (e.g., from a user, a content server or other source). Search interface  230  may send queries to search modules  240 . Federator  245  may gather the results from all search modules  240  together, and generate a response to the query received through search interface  230 . Search modules  240  are responsible for performing searches on an index partition, computing relevance score, sorting results, and retrieving metadata regions to return. 
     In the above example, a user has constructed the search queries. It should be noted, however, that the user could be any system that issues queries to the search system, and may include other computer programs searching on behalf of other users, creating reports or running automatic processes. Since there can be many different types of metadata and/or attributes in the search index, the search queries are not restricted to “text” based search terms. 
       FIG.  2    is provided by way of example. Search engine  222  may include any number of other modules or configurations to update and search index  224 . For example, search modules  240  and indexing engines  220  may be a single module. Search engine  222  may be a portion of a larger program, such as a document management program, may be a separate program or may be implemented according to any suitable programming architecture. Furthermore, the processes of search engine  222  may be distributed across multiple computer systems. Additionally, while in  FIG.  2   , index  224  is illustrated as a single index, index  224  may comprise a set of smaller or different indices as will be discussed. 
     It will be recalled from the above discussion that one problem that occurs in conjunction with the use of these types of search engines is that a searching user may enter a search term (often referred to as a keyword) that may not necessarily be the keyword that will obtain a desired search result. For example, the user may misspell a search term. Or, a user may enter a homophone of the actual word he wishes to search for (e.g., the user may desire to search for “whale” but may enter “wail”). Accordingly, some search systems may provide suggestions to a searching user for additional, different or substitute search terms based on the search terms the user enters. By allowing a user to select additional or substitute terms, higher quality (e.g., more relevant or responsive) search results may be returned in response to a search. It is desired, however, to provide high quality suggestions based on the sounds of original search terms and the frequency of terms as used in the corpus of documents being searched. 
     To that end, among others, attention is now directed to embodiments of systems and methods for providing search term suggestions in a search system as disclosed herein. Embodiments as disclosed may utilize the sound of an original search term to locate candidate terms based on the sound of the candidate terms and the frequency of appearance of the candidate terms in the corpus of documents being searched. A set of search term suggestions can then be determined from the candidate terms and returned to the user as search term suggestions for the original search term. 
       FIG.  3 A  depicts a diagrammatic representation of one embodiment of search engine  322  including a term recommender  304  utilized in association with search interface  330 . The search interface  330  may allow a user or other application to submit a search query comprising one or more search terms. The search interface  330  may communicate one or more search terms of the query to the term recommender  304 , which may return one or more search term suggestions to the search interface  330 . The search interface  330  can present the search term suggestions to a user and allow the user to select a search term suggestion as an additional or replacement search term for the search query. The search query can then be passed to search module  340  which executes the search query on the documents  307  of the repository  305  using search index  326  of index  324  to identify documents  307  responsive to the search query. A list or other representation of those responsive documents  307  may be provided to the user through the search interface  330 . 
     Term recommender  304  may thus receive an original search term from search interface  330  and provide one or more search term suggestions in response. The search term suggestions may be based on the sound of the original search term and the frequency of appearance of terms in the documents  307  of the repository  305 . To facilitate the generation of search term suggestions, search engine  322  includes phonetic encoder modules  310  (e.g.,  310   a ,  310   b ,  310   n ). Each phonetic encoder module  310  may employ a different phonetic encoder or phonetic encoding algorithm to create a (phonetic) code for an input term and may return the generated code or one or more terms used in the corpus of documents  307  associated with the code generated for the input term. Examples of phonetic encoders of phonetic encoding algorithms that may be employed by phonetic encoder modules  310  include Exact Match, Metaphone, Double Metaphone, Soundex, Caverphone, and Daitch-Mokotoff, among others. 
     Accordingly, the phonetic encoder module  310  may include an interface by which a code may be requested for an input term. When an input term is received via this interface, the phonetic encoder of the phonetic encoder module  310  may be applied to the input term to generate a code and the code returned. Another interface may be provided by phonetic encoder module  310  by which a set of terms associated with an input term may be requested. For this latter interface, in some embodiments a frequency may also be specified such that only terms associated with an input term that appear more (in the corpus of documents  307 ) than the specified frequency will be returned. In particular, in one embodiment, the interface may allow the frequency to be defined by the input term itself, such that only terms associated with an input term that appear more (in the corpus of documents  307 ) than the input term will be returned. To determine the terms to return, the phonetic encoder module may search sound index  328  based on the code generated from the input term. 
     More specifically, the sound index  328  may include one or more entries for each term utilized in the corpus of documents  307 , where the term is associated with the set of sound codes generated for the term by each of phonetic encoder modules  310 . The entry for the term may also specify the frequency (e.g., number of occurrences) of the term in corpus of documents associated with the search system. Each entry in the sound index may thus comprise a term that appears in the corpus, a code (e.g., a code for the term generated by a phonetic encoder module  310  utilized by the search system) and a frequency for the term. Each entry could be stored, for example as a triple (&lt;code, frequency, term&gt;) such that the entries in the sound index are ordered first by code, then by frequency. As an example, a portion of the entries in the sound index  328  could appear as follows: 
     
       
         
           
               
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 hmfn 
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                 homophone 
               
               
                   
                   
               
            
           
         
       
     
     Indexing engine  320  may create or update entries in sound index  328  when indexing a document  307  of the corpus. Specifically, when an indexing interface  300  receives an indexing requests, the document  307  may be passed to indexing engine  320  to analyze the document  307  to determine information to be indexed in index  324 . As discussed, a tokenizer converts the document  307  being indexed into discrete terms that are used to create or update entries in index  324  to indicate which terms the document contains in search index  326 . Additionally, for each term of the document  307  being indexed, it can be determined if the term is currently in the sound index  328  (e.g., by searching on the term in the sound index). If the term has previously been indexed in the sound index  328 , the frequency counts associated with each entry in the sound index associated with that term may be incremented. If, however, the term is not in the sound index  328 , for each phonetic encoder module  310  utilized by the search system, that phonetic encoder of the module may be utilized to generate a corresponding code for the term. An entry in the sound index  328  for that code, a frequency of 1 and the term may then be created. For example, the term may be provided as input to phonetic encoder module  310   a  via an interface that returns a code generated by the phonetic encoder employed by phonetic encoder module  310   a . The code returned by the phonetic encoder module  310   a  may then be used by indexing engine  320  to create an entry in the sound index  328  for that code, a frequency of 1 and the term. The same can be repeated for phonetic encoder modules  310   b ,  310   n , etc. In this manner, new entries in the sound index  328  corresponding to that term and the codes generated by each phonetic encoder module  310  of the search engine  322  may be created. 
     Accordingly, when a phonetic encoder module  310  receives a request for a set of terms associated with an input term, the phonetic encoder module  310  may generate a code for the input term using the phonetic encoder and search the sound index  328  for entries for that code. In some embodiments, this search may be a search for entries in the sound index  328  having that code and a frequency over a certain frequency threshold. This frequency threshold may be specified in the received request or may be determined by determining the frequency of the input term from the sound index  328  (e.g., searching the sound index  328  for an entry associated with the input term and using the frequency associated with that entry as the frequency threshold). As the entries in the sound index  328  may be sorted by code and frequency, the search of the sound index  328  for a code and frequency may be accomplished relatively quickly. The terms associated with the entries in the sound index  328  returned from the search may be returned by the phonetic encoder module  310  in response to the received request. 
     Term recommender  304  may thus utilize these phonetic encoder modules  310  to determine one or more search term suggestions to provide in response to receiving an original search term from search interface  330 . In particular, term recommender  304  may call one or more phonetic encoder module  310  with the original search term to request a candidate set of terms. The term recommender  304  may also determine the frequency (of appearance in the corpus of documents  307 ) of the original search term (e.g., by accessing sound index  328  as described) and provide this frequency in the request to each phonetic encoder module  310 , such that each phonetic encoder module  310  may only return candidate terms that occur with greater frequency than the original search term. 
     In some embodiments, these phonetic encoder modules  310  may be ordered such that they may be evaluated according to the order to determine the set of candidate terms generated by each phonetic encoder module  310  until a threshold number of candidate terms is obtained. In another embodiment, an initial phonetic encoder module (e.g., phonetic encoder module  310   a  employing an Exact Match phonetic encoder) may be called to determine the candidate set of terms. If no terms are returned by the initial phonetic encoder module  310  (or less than a candidate threshold number of terms are returned), one or more, or all of the other phonetic encoder modules  310  may be utilized to generate the set of candidate search terms. 
     The candidate set of terms returned by each of the called phonetic encoder modules  310  can then be evaluated to select the set of suggested search terms from the candidate terms returned form the phonetic encoder modules  310 . In one embodiment, the term recommender  304  may utilize term scoring module  302  to rank the candidate terms returned from the called phonetic encoder modules  310  based on the frequency (of appearance in the corpus of documents  307 ) of a candidate term or the sound distance of a candidate term from the original search term. 
     The sound distance may be an edit distance (e.g., a Levenshtein distance) of the between the phoneme sequence of the original search term and the phoneme sequence of the candidate search term. In other words, the minimum number of operations required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. Term recommender  304  may thus include a sound distance module  306  for determining an edit distance between two terms. The sound distance module  306  may generate phoneme sequences for each term and a sound distance based on a determination of the number of operations required to transform the phoneme sequence of one term to the phoneme sequence of the other term. The sound distance module  306  may be utilized by term scoring module  302  to determine the sound distance between the original search term and a candidate search term. 
     Additionally, in one embodiment, sound distance module  306  may determine the sound distance based on weights associated with the type of operations or steps required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. The weights may be greater for relatively big operations (e.g., substituting a vowel with a consonant, substituting a consonant with a different consonant, inserting or deleting a consonant) and lesser for relatively smaller magnitude operations (e.g., substituting a vowel with another vowel, substituting a consonant with a similar consonant, inserting or deleting a vowel). The greater weights may be, for example, approximately twice the lesser weights. Thus, to determine a sound distance, the sound distance module  306  may determine not only the minimum number of operations required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term but a type for each of the operations. 
     For example, in one embodiment, sound distance module  306  may determine the sound distance between two terms as follows:
         Given two sequences a and b,   m is the length of a, i is the index of a;   n is the length of b, j is the index of b;   d is the matrix used to calculate the distance, d(i,j) is the minimum distance of a [0, i−1] and b [0, j−1]. d i,j (i=m, j=n) is the result.       

     
       
         
           
             
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     Once a sound distance is determined for each of the candidate terms, term recommender  304  may rank the candidate terms based on the frequency or sound distance. For example, the candidate terms may be ranked according to sound distance (with the least sound distance having a higher ranking) and candidate terms with the same sound distance ranked relative to one another according to frequency (of appearance in the corpus), with a candidate term with greater frequency ranking higher than a candidate term with a lesser frequency. As another example, a formula may be used to consider both the frequency and sound distance for each candidate term to generate a score for each candidate term and the candidate terms ranked according to their score. One example of such a formula is 
     
       
         
           
             
               
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     As our one more example, to rank the set of candidate terms, the terms may first be ranked according to the number of phonetic encoding modules  310  that returned the candidate term (where a candidate term returned by a greater number of phonetic encoding modules  310  is ranked higher that a candidate term returned by fewer phonetic encoding modules  310 ). Candidate terms returned by the same number of phonetic encoding modules  310  may then be ordered by their frequency of occurrence in the corpus or by their sound distance score. Other methods of ranking the candidate search terms are also possible. 
     Term recommender module  304  may then select one or more of the set of candidate terms based on their ranking and return the selected candidate terms to the user through search interface  330  as search term suggestions. For example, the top five ranked candidate terms may be selected and returned as search term suggestions. 
     It will be noted that embodiments of term recommenders and search systems that utilize such term recommenders may be usefully applied in a variety of contexts and environments. For example, embodiments of search systems that utilize term recommenders may be usefully deployed in a cloud based computer environment, as depicted in the embodiment illustrated in  FIG.  3 B . Cloud based computer environment  398  may be a network of distributed servers. In some embodiments, cloud computing environment  398  may defined by a network of distributed servers under the control of an organization on behalf of a set of users or clients who may access one or more of a set of software or other services executing on the servers remotely and which may be accessible over a computer based network  396 . In some instances still, the organization is an external organization independent of the users or clients. 
     The various components of a term recommender or search system may thus be deployed in the cloud based computing environment  398  by deploying services associated with a with the search system using the cloud based computer environment  398 . By deploying the modules of the search system in the cloud as services or other cloud based applications (collectively services), such services can utilize the storage or other functionality provided by the cloud provider while achieving increased security, accessibility or reliability. In the depicted embodiment, for example, the index  374 , including the search index  376  and sound index  378  may be stored in the cloud storage  394  along with the repository  355  including documents  357 . Examples of cloud based computing environment include, for example, Amazon Web Services or Elastic Compute Cloud, Microsoft Azure and Google Cloud Platform. Web Services 
     In such an embodiment then, term recommender  354  may be deployed in a term recommender service  381  having a term recommender interface  385  accessible through a web services or other type of interface such as Representational State Transfer (REST) interface, a Simple Object Access Protocol (SOAP) interface, an Application Programming Interface (API) or another type of interface accessible over a computer based network. Thus, request for the term recommender  354  may be received and responded to through the term recommender interface  385 . 
     Similarly, indexing engine  370  may be deployed in an indexing service  370  having an indexing interface  350  which may a RESTful interface, a SOAP interface, an API or another type of interface. Here, requests for use of the indexing engine  370  may be received and responded to through the indexing interface  350 . Likewise, phonetic encoder module  360  may be provided in a phonetic encoder service  384  accessible through a phonetic encoder interface  388  (again, which may be a RESTful interface, a SOAP interface, an API or another type of interface). Requests for the use of one or more phonetic encoders  360  (which may specified in a request to the phonetic encoder interface  388 ) may be received and responded to through the phonetic encoder interface  388 . 
     In this embodiment, then, search  390  and search interface  380  may be deployed in a search service  382  where the search interface  380  may be a RESTful interface, a SOAP interface, an API or another type of interface such that the search interface  330  may allow a user or other application to submit a search query comprising one or more search terms over the network  396 . While it will be understood with respect to the following description that similarly named components may operate similarly to those described above, and will not be described fully again with respect to  FIG.  3 B , it may be useful to discuss briefly the operation of the search system and term recommender  354  as depicted. 
     Accordingly, when the search interface  380  receives a search over the network  396 , the search interface  380  may communicate one or more search terms of the query to the term recommender  354  (e.g., it may send a request for term suggestions to the term recommender interface  385  of term recommender service  380  with the search or one or more terms of the search). The term recommender  354  may return one or more search term suggestions to the search interface  380 . For example, a response to the request received at term recommender interface  385  may be returned to the requesting search interface  380  where the response includes the suggested search terms. The search interface  380  can present the search term suggestions to a user and allow the user to select a search term suggestion as an additional or replacement search term for the search query. For example, a response to the search request received at search interface  380  may be returned over network  396  where the response includes the search term suggestions. The search query can then be passed to search module  390  which executes the search query on the documents  357  of the repository  355  using search index  376  of index  374  to identify documents  357  responsive to the search query. A list or other representation of those responsive documents  357  may be provided to the user through the search interface  380 . 
     Term recommender  354  may thus receive an original search term from search interface  380  (e.g., through term recommender interface  385  that received the request for term suggestions from the search interface  380 ) and provide one or more search term suggestions in response (e.g., through term recommender interface  385 ) using sound distance module  366  and term scoring module  362 . The search term suggestions may be based on the sound of the original search term and the frequency of appearance of terms in the documents  357  of the repository  355 . To facilitate the generation of search term suggestions, phonetic encoder modules  360  (e.g.,  360   a ,  360   b ,  360   n ) of phonetic encoder interface service  384  may be used as discussed above. 
     Accordingly, phonetic encoder interface  388  of phonetic encoder interface service  384  may provide an interface by which a code may be requested for an input term from one or more of the phonetic encoder modules  360 . When an input term is received via this interface, the phonetic encoder of the phonetic encoder module  360  may be applied to the input term to generate a code and the code returned (e.g., through the phonetic encoder interface  388 ). Another interface may be provided by phonetic encoder interface  388  through which a set of terms associated with an input term may be requested. For this latter interface, in some embodiments, a frequency may also be specified such that only terms associated with an input term that appear more (in the corpus of documents  357 ) than the specified frequency will be returned. In particular, in one embodiment, the interface may allow the frequency to be defined by the input term itself, such that only terms associated with an input term that appear more (in the corpus of documents  357 ) than the input term will be returned (e.g., through phonetic encoder interface  388 ). To determine the terms to return, the phonetic encoder interface service  384  or phonetic encoder interface  388 ) may search sound index  378  based on the code generated from the input term. 
     Indexing engine  370  may create or update entries in sound index  378  when indexing a document  357  of the corpus. Specifically, indexing service  386  may receive request to index a document over network  396 . The request may include, for example, the content of the document or a location of the document to index. When the indexing interface  350  receives an indexing request, the document  357  may be passed to indexing engine  370  to analyze the document  357  to determine information to be indexed in index  374  according to phonetic code or frequency, as discussed. The index  374  can thus be searched by phonetic encoder modules  360  to determine a set of terms associated with an input term based on phonetic code or frequency. 
     Term recommender  354  may thus utilize these phonetic encoder modules  360  (by accessing them through phonetic encoder interface  388 ) to determine one or more search term suggestions to provide in response to receiving an original search term in a request from search interface  380  as discussed above. The determined search terms can then be provided to the search interface  380  (e.g., a response to the request received at term recommender interface  385  may be returned to the requesting search interface  380  where the response includes the determined search terms) such that the search interface  380  can return these determined search terms as search term suggestions. 
     Referring now to  FIG.  4   , a flow diagram for one embodiment of a method of indexing a document in a search system to create a sound index is depicted. A document may be received (STEP  402 ) and stored in the corpus of documents for the search system (STEP  404 ). A tokenizer converts the document being indexed into discrete terms (STEP  406 ). For each of these terms (STEP  408 ), the search index of the search system is created or updated to indicate which terms the document contains (STEP  410 ). Additionally, it can be determined if the term is currently in the sound index by searching on the term in the sound index (STEP  412 ). If the term has previously been indexed in the sound index (Y branch of STEP  412 ), the frequency counts associated with each entry in the sound index associated with that term may be incremented (STEP  414 ). If the last term has processed (Y branch of STEP  424 ) the indexing of the document may end. Otherwise, the next term is processed (STEP  408 ). 
     If, however, the term is not in the sound index (N branch of STEP  412 ) for each phonetic encoder utilized by the search system (STEP  416 ), that phonetic encoder may be utilized to generate a corresponding code for the term (STEP  418 ). An entry in the sound index for that code, a frequency of 1 and the term may then be created (STEP  420 ). Once all encoders have been utilized to generate codes and create entries (Y branch of STEP  422 ), the next term may be processed if any terms remain (N branch of STEP  424 ). If the last term has processed (Y branch of STEP  424 ), the indexing of the document may end. 
     Moving to  FIG.  5   , a flow diagram of one embodiment of a method for providing search term suggestions in a search system is depicted. Initially, an original search term is received (STEP  502 ). This original search term may be provided, for example, by a user through a search interface as part of a search query or the like. The frequency of appearance in a corpus of documents of the original search term can then be determined (STEP  504 ). This determination may be made, for example, by accessing a sound index having entries indicating the frequency of occurrence of terms (e.g., along with their sound code). The determination may also be made by accessing another index or source of data in the search system where such a frequency is maintained. In one embodiment, search suggestions may only be provided if the frequency of the original search term is above a certain threshold. In other embodiments, search suggestions may substantially always be provided. 
     A set of candidate terms for search suggestions may then be determined (STEP  506 ). These candidate search terms may be determined using a set of phonetic encoder modules that generate candidate terms for the original search term by generating a sound code for the original search term according to a phonetic encoder and determining terms that both have the same sound code as the original search term and occur in the corpus of documents of the search system more frequently than the original search term. 
     In some embodiments, these phonetic encoder modules may be ordered such that they may be evaluated according to the order to determine the set of candidate terms generated by each phonetic encoder module until a threshold number of candidate terms is obtained. In another embodiment, an initial phonetic encoder module (such as a phonetic encoder module employing an Exact Match phonetic encoder) may be called to determine the candidate set of terms. If no terms are returned by the initial phonetic encoder module (or less than a candidate threshold number of terms are returned), one or more, or all of the other phonetic encoder modules may be utilized to generate the set of candidate search terms. In one embodiment, if the initial encoder module (e.g., the Exact Match phonetic encoder module) returns any candidate terms, these candidate terms may be ranked based on frequency of appearance of these candidate terms in the corpus and a number of these top ranked candidate terms selected as search term suggestions. 
     Once the set of candidate terms is determined, for each of the candidate search terms (STEP  508 ), a sound edit distance may be determined (STEP  510 ). The sound distance may be an edit distance (e.g., a Levenshtein distance) of the between the phoneme sequence of the original search term and the phoneme sequence of the candidate search term. In other words, the minimum number of operations required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. Additionally, in one embodiment, the sound distance may be determined based on weights associated with the type of operations or steps required to transform the phoneme sequence of the candidate term to the phoneme sequence of the original search term. The weights may be greater for relatively big operations (e.g., substituting a vowel with a consonant, substituting a consonant with a different consonant, inserting or deleting a consonant) and lesser for relatively smaller magnitude operations (e.g., substituting a vowel with another vowel, substituting a consonant with a similar consonant, inserting or deleting a vowel). The greater weights may be, for example, approximately twice the lesser weights. 
     Once a sound distance is determined for each of the candidate terms (Y branch of STEP  516 ), the set of candidate terms may be ranked (STEP  518 ). This ranking may be, for example, based on the frequency of the candidate search term or the sound distance determined for the candidate term. For example, the candidate terms may be ranked according to sound distance (with the candidate terms having the least sound distance having a higher ranking) and candidate terms with the same sound distance ranked relative to one another according to frequency (of appearance in the corpus), with a candidate term with greater frequency ranking higher than a candidate term with a lesser frequency. As another example, a formula may be used to consider both the frequency and sound distance for each candidate term to generate a score for each candidate term and the candidate terms ranked according to their score. One example of such a formula is 
     
       
         
           
             
               
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     As but one more example, to rank the set of candidate terms, the terms may first be ranked according to the number of phonetic encoding modules that returned the candidate term (where a candidate term returned by a greater number of phonetic encoding modules is ranked higher that a candidate term returned by fewer phonetic encoding modules). Candidate terms returned by the same number of phonetic encoding modules may then be ordered by their frequency of occurrence in the corpus or by their sound distance score. Again, in one embodiment, if the initial encoder module (e.g., the Exact Match phonetic encoder module) returns any candidate terms, these candidate terms may be ranked based on frequency of appearance of these candidate terms in the corpus (in this case, the sound distance for each candidate term may not need to be determined). Other methods of ranking the candidate search terms are also possible. One or more of the set of candidate terms may be selected based on their ranking and the selected candidate terms returned to the user through a search interface as search term suggestions (STEP  520 ). For example, the top five ranked candidate terms may be selected and returned as search term suggestions. 
     Although the invention has been described with respect to specific embodiments thereof, these embodiments are merely illustrative, and not restrictive of the invention. The description herein of illustrated embodiments of the invention, including the description in the Abstract and Summary, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein (and in particular, the inclusion of any particular embodiment, feature or function within the Abstract or Summary is not intended to limit the scope of the invention to such embodiment, feature or function). Rather, the description is intended to describe illustrative embodiments, features and functions in order to provide a person of ordinary skill in the art context to understand the invention without limiting the invention to any particularly described embodiment, feature or function, including any such embodiment feature or function described in the Abstract or Summary. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the invention in light of the foregoing description of illustrated embodiments of the invention and are to be included within the spirit and scope of the invention. Thus, while the invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances, some features of embodiments of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Therefore, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the invention. 
     Reference throughout this specification to “one embodiment”, “an embodiment”, or “a specific embodiment” or similar terminology means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment and may not necessarily be present in all embodiments. Thus, respective appearances of the phrases “in one embodiment”, “in an embodiment”, or “in a specific embodiment” or similar terminology in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any particular embodiment may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments described and illustrated herein are possible in light of the teachings herein and are to be considered as part of the spirit and scope of the invention. 
     In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that an embodiment may be able to be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, components, systems, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention. While the invention may be illustrated by using a particular embodiment, this is not and does not limit the invention to any particular embodiment, and a person of ordinary skill in the art will recognize that additional embodiments are readily understandable and are a part of this invention. 
     Embodiments discussed herein can be implemented in a computer communicatively coupled to a network (for example, the Internet), another computer, or in a standalone computer. As is known to those skilled in the art, a suitable computer can include a CPU, at least one read-only memory (“ROM”), at least one random access memory (“RAM”), at least one hard drive (“HD”), and one or more input/output (“I/O”) device(s). The I/O devices can include a keyboard, monitor, printer, electronic pointing device (for example, mouse, trackball, stylus, touch pad, etc.), or the like. 
     ROM, RAM, and HD are computer memories for storing computer-executable instructions executable by the CPU or capable of being complied or interpreted to be executable by the CPU. Suitable computer-executable instructions may reside on a computer-readable medium (e.g., ROM, RAM, and/or HD), hardware circuitry or the like, or any combination thereof. Within this disclosure, the term “computer-readable medium” is not limited to ROM, RAM, and HD and can include any type of data storage medium that can be read by a processor. For example, a computer-readable medium may refer to a data cartridge, a data backup magnetic tape, a floppy diskette, a flash memory drive, an optical data storage drive, a CD-ROM, ROM, RAM, HD, or the like. The processes described herein may be implemented in suitable computer-executable instructions that may reside on a computer-readable medium (for example, a disk, CD-ROM, a memory, etc.). Alternatively, the computer-executable instructions may be stored as software code components on a direct access storage device array, magnetic tape, floppy diskette, optical storage device, or other appropriate computer-readable medium or storage device. 
     Any suitable programming language can be used to implement the routines, methods or programs of embodiments of the invention described herein, including C, C++, Java, JavaScript, HTML, or any other programming or scripting code, etc. Other software/hardware/network architectures may be used. For example, the functions of the disclosed embodiments may be implemented on one computer or shared/distributed among two or more computers in or across a network. Communications between computers implementing embodiments can be accomplished using any electronic, optical, radio frequency signals, or other suitable methods and tools of communication in compliance with known network protocols. 
     Different programming techniques can be employed such as procedural or object oriented. Any particular routine can execute on a single computer processing device or multiple computer processing devices, a single computer processor or multiple computer processors. Data may be stored in a single storage medium or distributed through multiple storage mediums, and may reside in a single database or multiple databases (or other data storage techniques). Although the steps, operations, or computations may be presented in a specific order, this order may be changed in different embodiments. In some embodiments, to the extent multiple steps are shown as sequential in this specification, some combination of such steps in alternative embodiments may be performed at the same time. The sequence of operations described herein can be interrupted, suspended, or otherwise controlled by another process, such as an operating system, kernel, etc. The routines can operate in an operating system environment or as stand-alone routines. Functions, routines, methods, steps and operations described herein can be performed in hardware, software, firmware or any combination thereof. 
     Embodiments described herein can be implemented in the form of control logic in software or hardware or a combination of both. The control logic may be stored in an information storage medium, such as a computer-readable medium, as a plurality of instructions adapted to direct an information processing device to perform a set of steps disclosed in the various embodiments. Based on the disclosure and teachings provided herein, a person of ordinary skill in the art will appreciate other ways and/or methods to implement the invention. 
     It is also within the spirit and scope of the invention to implement in software programming or code any of the steps, operations, methods, routines or portions thereof described herein, where such software programming or code can be stored in a computer-readable medium and can be operated on by a processor to permit a computer to perform any of the steps, operations, methods, routines or portions thereof described herein. The invention may be implemented by using software programming or code in one or more general purpose digital computers, by using application specific integrated circuits, programmable logic devices, field programmable gate arrays, optical, chemical, biological, quantum or nanoengineered systems, components and mechanisms may be used. In general, the functions of the invention can be achieved by any means as is known in the art. For example, distributed or networked systems, components and circuits can be used. In another example, communication or transfer (or otherwise moving from one place to another) of data may be wired, wireless, or by any other means. 
     A “computer-readable medium” may be any medium that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, system or device. The computer-readable medium can be, by way of example only but not by limitation, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, system, device, propagation medium, or computer memory. Such computer-readable medium shall generally be machine readable and include software programming or code that can be human readable (e.g., source code) or machine readable (e.g., object code). Examples of non-transitory computer-readable media can include RAMs, ROMs, HDs, data cartridges, magnetic tapes, floppy diskettes, flash memory drives, optical data storage devices, CD-ROMs, and other appropriate computer memories and data storage devices. In an illustrative embodiment, some or all of the software components may reside on a single server computer or on any combination of separate server computers. As one skilled in the art can appreciate, a computer program product implementing an embodiment disclosed herein may comprise one or more non-transitory computer-readable media storing computer instructions translatable by one or more processors in a computing environment. 
     A “processor” includes any hardware system, mechanism or component that processes data, signals or other information. A processor can include a system with a general-purpose CPU, multiple processing units, dedicated circuitry for achieving functionality, or other systems. Processing need not be limited to a geographic location, or have temporal limitations. For example, a processor can perform its functions in “real-time,” “offline,” in a “batch mode,” etc. Portions of processing can be performed at different times and at different locations, by different (or the same) processing systems. 
     It will also be appreciated that one or more of the elements depicted in the drawings/figures can also be implemented in a more separated or integrated manner, or even removed or rendered as inoperable in certain cases, as is useful in accordance with a particular application. Additionally, any signal arrows in the drawings/figures should be considered only as exemplary, and not limiting, unless otherwise specifically noted. 
     As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having,” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, product, article, or apparatus that comprises a list of elements is not necessarily limited only those elements but may include other elements not expressly listed or inherent to such process, product, article, or apparatus. 
     Furthermore, the term “or” as used herein is generally intended to mean “and/or” unless otherwise indicated. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). As used herein, including the claims that follow, a term preceded by “a” or “an” (and “the” when antecedent basis is “a” or “an”) includes both singular and plural of such term, unless clearly indicated within the claim otherwise (i.e., that the reference “a” or “an” clearly indicates only the singular or only the plural). Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
     Although the foregoing specification describes specific embodiments, numerous changes in the details of the embodiments disclosed herein and additional embodiments will be apparent to, and may be made by, persons of ordinary skill in the art having reference to this disclosure. In this context, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of this disclosure. Accordingly, the scope of this disclosure should be determined by the following claims and their legal equivalents.