Understanding phonetic symbols

Speech sound symbols

Each language uses its own inventory of SPR symbols to represent the speech sounds of that language. The following rules apply to specifying an SPR symbol:

• Letters are case-sensitive, so e and E, for example, represent two different sounds.
• Two- and three-character symbols must be enclosed in single quotes when indicated in the symbol tables. The single quotes indicate that the multiple characters are actually a single symbol. For example, the symbol 'aj' in the German word heim is specified as "h'aj'm".
• Some three-character symbols include single quotes around only two of the characters. The single quotes indicate that the two characters are a single symbol. So the SPR consists of two symbols. For example, the symbol 'a:'n in the Netherlands Dutch word dependances contains two symbols, 'a:' and n, and is specified as d'e:'.pEn.1d'a:'n.s@s.

Also consider the following when defining a word's pronunciation in SPR format:

• The sounds of every language have specific distributional patterns within that language. For example, in all dialects of English, the sound G in sing (".1sIG") does not occur at the beginning of a word. Other US English sounds that have a particularly narrow distribution are the glottal stop (?), the flap (F), and the syllabic nasal (N). If you enter a sound symbol in a context in which it does not normally occur, the resulting speech might sound unnatural.
• The service applies a sophisticated set of linguistic rules to its input to reflect the processes by which sounds change in specific contexts in natural language. For example, in US English, the sound t of the word write (".1r1Yt") is pronounced as a flap (F) in writer (".1rY.0FR"). SPR input undergoes these modifications just as ordinary input text does. In this example, whether you enter ".1rY.0tR" or ".1rY.0FR" does not affect the speech that is generated.

Syllable boundaries

You can use a . (period, IPA Unicode 002E) to mark the beginning of each syllable in SPR or IPA. However, to preserve the valid phonetics of a language, the service can elect not to honor periods in some cases (for example, if a syllable boundary is placed at an illegal or unnatural position for a language). In general, in cases where you can indicate a valid preference for a syllable boundary or other aspect of a word's pronunciation, the service honors such requests.

Syllable stress

Table 1 identifies the symbols that you can use to indicate syllable stress for a pronunciation. IBM recommends that you indicate primary stress for pronunciations in either SPR or IPA. However, indicating syllable stress is optional for both formats; the service determines where stress occurs if you do not indicate it.

You must place a syllable stress marker within a syllable boundary but always to the left of the syllable's vowel. You can place a marker anywhere to the left of the stressed vowel. For example, each of the following SPR examples places the primary stress (1) on the correct vowel of the word construction:

<phoneme alphabet="ibm" ph="kXn1strHkSXn">construction</phoneme>
<phoneme alphabet="ibm" ph="kXns1trHkSXn">construction</phoneme>
<phoneme alphabet="ibm" ph="kXnst1rHkSXn">construction</phoneme>
<phoneme alphabet="ibm" ph="kXnstr1HkSXn">construction</phoneme>

Language-specific rules for using syllable stress

Table 2 lists language-specific considerations that apply to specifying syllable stress. Unless the table qualifies the rules for a language, you can use the syllable stress symbols described in the previous section.