<?xml version="1.0" standalone="yes"?>
<Paper uid="J97-4001">
  <Title>Algorithms for Grapheme-Phoneme Translation for English and French: Applications for Database Searches and Speech Synthesis</Title>
  <Section position="9" start_page="518" end_page="519" type="concl">
    <SectionTitle>
9. Conclusions
</SectionTitle>
    <Paragraph position="0"> We have presented the difficulties of grapheme-to-phoneme conversion for English and French. Both languages have evolved from different origins, and are the results of the historical influence of other languages from which words have been borrowed and assimilated, sometimes only partially. English and French have interacted and continue to interact with each other. For both languages, the spelling has been enforced by dictionaries and laws, but the pronunciation has continued to evolve, widening the gap between the written and spoken components of the language.</Paragraph>
    <Paragraph position="1"> Both the English and French translation systems presented in this paper are based on rewriting rules. Nevertheless, some differences exist in the syntax and the interpretation of these rules. For a more theoretical approach to rewriting rules, see Kaplan and Kay (1994).</Paragraph>
    <Paragraph position="2"> English is scanned once from right to left to better take into account the suffixes of the word, which in certain cases determine the stressed syllable. The rule transforms the grapheme into phonemes and stress marks used by the stress module. In some cases, the input string is modified to add a morpheme boundary, or to replace the suffix by another suffix to continue the conversion. Syllabification, stress, and allophonic rules are achieved by programs.</Paragraph>
    <Paragraph position="3"> French uses the concept of a class that allows for the grouping of strings having a common property, thus reducing the number of rules. Several blocks of rules can be defined corresponding to different scans from left to right of the string (the output string replacing the input text at the end of a block of rules). The input string is not modified. Rules can check the left and right contexts of the input string, and the left context of the output string. French is not a stressed language, so there is no need for a syllabification module or a stress module.</Paragraph>
    <Paragraph position="4"> Many problems persist for phonemicization. In English, suffix stripping, compound decomposition, and primary stressed syllable are very important to get the proper phoneme string, and are carried out mostly by rules without an explicit morph dictionary, contrary to as in Allen (1976), who uses a morph dictionary with 12,000 morphs, or Coker (1985), whose dictionary has 43,000 morphs. In French, the word-by-word conversion is probably simpler due to the absence of stressed syllables. Affixes do not alter the pronunciation of the root; compare, for instance, photo, photograph, and photography in English with photo, photographe and photographie in French. But in French, there are more interactions between words due to the linking problem (nous avons) and mute e (chemin defer). These interactions are also dependent on speech rate.</Paragraph>
    <Paragraph position="5"> Sometimes the homograph problem can be solved by looking at the left and right context of the word, but the general case requires a better understanding of the overall 13 The synthetic index is Is = w + m, where w is a word and m is a morpheme.</Paragraph>
    <Paragraph position="6">  Computational Linguistics Volume 23, Number 4 structure of the sentence. This is also required to get a more natural prosodics in text-to-speech synthesizers.</Paragraph>
    <Paragraph position="7"> The same formalism could be used for both English and French with a slight modification, for instance, of the French formalism. Blocks of rules should indicate if the scan is to be done from left to right or from right to left. In the right-to-left scan, the right context of the output buffer would be usable (instead of the left context if the scan is done from left to right). The word scandalousness could be decomposed by the following rules: begin RL RL for Right to Left</Paragraph>
    <Paragraph position="9"> + in the output buffer resulting in scandal+ous+ness. Translating the root scandal could be done either from left to right or from right to left in one or more blocks of rules. The required output phoneme string depends on the application. For speech synthesis, one output string is needed for a word. If several pronunciations are possible, the software has to produce only one for the synthesizer.</Paragraph>
    <Paragraph position="10"> Speech recognition algorithms must know all the phonetic variations of the words in the vocabulary to be recognized, so the output should be a set of phonetic strings corresponding to the input word. Some rules must be declared optional, and the interpreter modified to take them into account.</Paragraph>
    <Paragraph position="11"> For database searches, a set of equivalences can be devised where two (or more) phonemes or allophones could be considered correct. For example, in many cases \[0\] and \[i\] can be considered equivalents. Similarly, \[o\]\[1\] and \[L\] (syllabic \[1\]) can also be considered equivalents. For French open \[a\] and close \[(1\] could be equivalent, as would be \[o\] and \[o\], or \[el and \[C\]. The search could even be done only on phoneme consonants (for proper name searches, for instance).</Paragraph>
    <Paragraph position="12"> To our knowledge, learning algorithms, although promising, have not (yet) reached the level of rule sets developed by humans. The automatic discovery of the underlying structure of a language is not easy, nor is the developing of a universal rewriting rule formalism for the different languages.</Paragraph>
    <Paragraph position="13"> Dictionaries and sets of rules will have to continue to coexist either as a dictionary of exceptions and a large set of rules, or as a large dictionary and a set of rules to deal with exceptions.</Paragraph>
  </Section>
class="xml-element"></Paper>