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PHONEME TABLES

A phoneme table defines all the phonemes which are used by a language, together with their properties and the data for their production as sounds.

Generally each language has its own phoneme table, although additional phoneme tables can be used for different voices within the language. These alternatives are referenced from Voice files.

A phoneme table does not need to define all the phonemes used by a language. It can inherit the phonemes from a previously defined phoneme table. For example, a phoneme table may redefine (or add) some of the vowels that it uses, but inherit most of its consonants from a standard set.

The source files for the phoneme data are in the "phsource" directory in the espeakedit download package. "Vowel files", which are referenced in FMT(), VowelStart(), and VowelEnding() instructions are made using the espeakedit program.

 

Phoneme files

The phoneme tables are defined in a master phoneme file, named phonemes. This starts with the base phoneme table followed by phoneme tables for other languages and voices. These inherit phonemes from the base table or previously defined tables.

In addition to phoneme definitions, the phoneme file can contain the following:

include <filename>
Includes the text of the specified file at this point. This allows different phoneme tables to be kept in different text files, for convenience. <filename> is a relative path. The included file can itself contain include statements.

phonemetable <name> <parent>
Starts a new phoneme table, and ends the previous table.
<name> Is the name of this phoneme table. This name is used in Voice files.
<parent> Is the name of a previously defined phoneme table whose phoneme definitions are inherited by this one. The name base indicates the first (base) phoneme table.

 

Phoneme definitions

Note: These new Phoneme definitions apply to eSpeak version 1.42.20 and later.

A phoneme table contains a list of phoneme definitions. Each starts with the keyword phoneme and the phoneme name (this is the name used in the pronunciation rules in a language's *_rules and *_list files), and ends with the keyword endphoneme. For example: 

  phoneme aI
    vowel
    starttype #a endtype #i
    length 230
    FMT(vowels/ai)
  endphoneme

  phoneme s
    vls alv frc sibilant
    voicingswitch z
    lengthmod 3
    Vowelin  f1=0  f2=1700 -300 300  f3=-100 80
    Vowelout f1=0  f2=1700 -300 250  f3=-100 80  rms=20

    IF nextPh(isPause) THEN
      WAV(ufric/s_)
    ELIF nextPh(p) OR nextPh(t) OR nextPh(k) THEN
      WAV(ufric/s!)
    ENDIF
    WAV(ufric/s)
  endphoneme

A phoneme definition contains both static properties and executed instructions. The instructions may contain conditional statements, so that the effect of the phoneme may be different depending on adjacent phonemes, whether the syllable is stressed, etc.

The instructions of a phoneme are interpreted in two different phases. In the first phase, the instructions may change the phoneme and replace it by a different phoneme. In the second phase, instructions are used to produce the sound for the phoneme.

The import_phoneme statement can be used to copy a previously defined phoneme from a specified phoneme table. For example: 

  phoneme t
    import_phoneme base/t[
  endphoneme
means: phoneme t in this phoneme table is a copy of phoneme t[ from phoneme table "base". A length instruction can be used after import_phoneme to vary the length from the original.

 

Phoneme Properties

Within the phoneme definition the following lines may occur: ( (V) indicates only for vowels, (C) only for consonants)

 

Phoneme Instructions

Phoneme Instructions may be included within conditional statements.

During the first phase of phoneme interpretation, an instruction which causes a change to a different phoneme will terminate the instructions. During the second phase, FMT() and WAV() instructions will terminate the instructions.

 

Conditional Statements

Phoneme definitions can contain conditional statements such as: 
  IF <condition> THEN
    <statements>
  ENDIF
or more generally: 
  IF <condition> THEN
    <statements>
  ELIF <condition> THEN
    <statements>
  ...
  ELSE
    <statements>
  ENDIF
where the ELSE and multiple ELSE parts are optional.

Multiple conditions may be joined with AND or OR, but not a mixture of ANDs and ORs.

A condition may be preceded by NOT. For example: 

  IF <condition> AND NOT <condition> THEN
    <statements>
  ENDIF

Condition Can be:

Attributes

 

Sound Specifications

There are three ways to produce sounds:

 

Vowel Transitions

These specify how a consonant affects an adjacent vowel. A consonant may cause a transition in the vowel's formants as the mouth changes shape between the consonant and the vowel. The following attributes may be specified. Note that the maximum rate of change of formant frequencies is limited by the speak program.