Speech synthesis using word parser with knowledge base having dictionary of morphemes with binding properties and combining rules to identify input word class

• US 5,651,095 A
• Filed: 02/08/1994
• Issued: 07/22/1997
• Est. Priority Date: 10/04/1993
• Status: Expired due to Term

• Current Assignee: British Telecommunications (BT Group Plc) (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Ogden, Richard
• Primary Examiner(s): Macdonald, Allen R.
• Assistant Examiner(s): Dorvil, Richemond
• Application Number:
  US08/193,537
• Time in Patent Office: 1,260 Days
• Field of Search: 395/2.67, 395/2.69, 395/2.85, 395/2.6, 395/2.66, 395/2.64, 381/36, 381/48, 381/51-52
• US Class Current: 704/260
• CPC Class Codes: G10L 13/10 Prosody rules derived from text; Stress or intonation

Abstract

A speech synthesis system includes a phonological converter, a word parser, a syllable parser, temporal and parametric interpreters, a file and a synthesizer. The word parser and syllable parser receive an input text which includes words in a defined word class. The word parser parses each word to determine whether it belongs to the defined class of words. The parser includes a knowledge base containing the individual morphemes utilized in the defined word class, each morpheme being a root or an affix, the binding properties of each root and each affix, the binding properties for each affix also defining the binding properties of the combination of the affix and another affix or another root, and a set of rules defining the manner in which the roots and affixes may be combined to fore words. The syllable parser determines the phonological features of the constituents of each syllable of the input text. The metrical parser determines the stress pattern of the syllables of each word. The temporal and parametric interpreters interpret the phonological features together with the stress pattern to produce a series of sets of parametric values for driving the synthesizer. The synthesizer produces a speech waveform. If desired, the parameter values may be stored in the file for later use.

Claims

1. A speech synthesis system for use in producing a speech waveform from an input text which includes words in a defined word class, said speech synthesis system including:

means for determining the phonological features of said input text;

means for parsing each word of said input text to determine if the word belongs to said defined word class, said parsing means including a knowledge base containing (1) the individual morphemes utilized in said defined word class, each morpheme being an affix or a root, (2) the binding properties of each root and each affix, the binding properties for each affix also defining the binding properties of the combination of each affix and one or more other morphemes, and (3) a set of rules for defining the manner in which roots and affixes may be combined to form words;

said means for parsing each word including means to determine whether a word being parsed consists of morphemes present in the knowledge base combined in accordance with said binding properties and said set of rules;

means responsive to the word parsing means for finding the stress pattern of each word of said input text; and

means for interpreting said phonological features together with the output from said means for finding the stress pattern to produce a series of sets of parameters for use in driving a speech synthesizer to produce a speech waveform.

2. A speech synthesis system as in claim 1, in which said means for determining the phonological features includes means to spread the phonological features for each syllable over a syllable tree for that syllable, the syllable tree dividing the syllable into an onset and a rime, and the rime into a nucleus and a coda.

3. A speech synthesis system as in claim 1, in which said input text is in the form of a string of input characters.

4. A speech synthesis system as in claim 1, including a memory for storing said series of sets of parameter values produced by the means for interpreting.

5. A speech synthesis system as in claim 1 including a speech synthesizer for converting said series of sets of parameter values into a speech waveform.

6. A speech synthesis system as in claim 5, in which said speech waveform is a digital waveform.

7. A speech synthesis system as in claim 5, in which said speech waveform is an analogue waveform.

8. A speech synthesis system as in claim 1 wherein:

said parsing means includes means for determining whether a word being parsed meets a predetermined criterion and, according to whether the word does or does not meet the said criterion, outputting information indicating respectively that the word does or does not belong to said defined class, said criterion being met by a word consisting of a root wherein the root is present in the knowledge base and has binding properties requiring no binding and said criterion being met by a word consisting of a root and at least one affix wherein said root and said affix are all present in the knowledge base and are combined in accordance with said binding properties and rules.

9. A method for use in producing a speech waveform from an input text which includes words in a defined word class, said method comprising the steps of:

determining the phonological features of said input text;

parsing each word of said input text to determine if the word belongs to said defined word class, said parsing step including using a knowledge base containing (1) the individual morphemes utilized in said defined word class, each morphemes being an affix or a root, (2) the binding properties of each root and each affix, the binding properties for each affix also defining the binding properties of the combination of each affix and one or more other morphemes, and (3) a set of rules for defining the manner in which roots and affixes may be combined to form words;

said parsing step including determining whether a word being parsed consists of morphemes present in the knowledge base combined in accordance with said binding properties and set of rules;

finding the stress pattern of each word of said input text, said finding step using the result of said parsing step; and

interpreting said phonological features together with the stress pattern found in said finding step to produce a series of sets of parameters for use in driving a speech synthesizer to produce a speech waveform.

10. A method as in claim 9, in which said step of determining the phonological features spreads the phonological features for each syllable over the syllable tree for that feature, the syllable tree dividing the syllable into an onset and as rime and the rime into a nucleus and a coda.

11. A method as in claim 9, in which said input text is in the form of a string of input characters.

12. A method as in claim 9, farther including the step of storing said series of sets of parameter values.

13. A method as in claim 9, further including the step of converting said series of sets of parameter values into a speech waveform.

14. A speech synthesis method as in claim 9 wherein:

said parsing step includes determining whether a word being parsed meets a predetermined criterion and, according to whether the word does or does not meet the said criterion, outputting information indicating respectively that the word does or does not belong to said defined class, said criterion being met by a word consisting of a root wherein the root is present in the knowledge base and has binding properties requiring no binding and said criterion being met by a word consisting of a root and at least one affix wherein said root and said affix are all present in the knowledge base and are combined in accordance with said binding properties and rules.