SPEECH SYNTHESIS SYSTEM

• US 20110196680A1
• Filed: 08/21/2009
• Published: 08/11/2011
• Est. Priority Date: 10/28/2008
• Status: Abandoned Application

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kato, Masanori
• Application Number:
  US13/125,507
• Publication Number:
  US 20110196680A1
• Time in Patent Office: Days
• US Class Current: 704/268
• CPC Class Codes: G10L 13/027 Concept to speech synthesisers; Generation of natural phrases from machine-based concepts generation of parameters for speech synthesis out of text G10L13/08
• CPC Class Codes: G10L 13/04 Details of speech synthesis systems, e.g. synthesiser structure or memory management

Abstract

When a system (100) is used for synthesizing speech having prosody serving as a reference, the system stores speech element information representing a speech element capable of synthesizing speech having a degree of naturalness indicating a degree of similarity to speech uttered by a human higher than a predetermined reference value (speech element information storage (115)). The system accepts requested prosody information representing prosody requested by the user (requested prosody information accepting part (113)). The system generates intermediate prosody information representing intermediate prosody between the reference prosody and the requested prosody (intermediate prosody information generator (114)). The system executes a speech synthesis process to synthesize speech based on the generated intermediate prosody information and the stored speech element information (speech synthesizer (116)).

Claims

1. A speech synthesis system comprising:

speech element information storage unit for storing speech element information representing a speech element capable of synthesizing speech having a degree of naturalness indicating a degree of similarity to speech uttered by a human higher than a predetermined reference value when the speech element is used for synthesizing speech having reference prosody which is prosody serving as a reference;

requested prosody information accepting unit for accepting requested prosody information representing requested prosody which is prosody requested by a user;

intermediate prosody information generating unit for generating intermediate prosody information representing intermediate prosody which is prosody between the reference prosody and the requested prosody; and

speech synthesizing unit for executing a speech synthesis process to synthesize speech based on the generated intermediate prosody information and the stored speech element information.

2. The speech synthesis system according to claim 1, wherein:

the speech synthesizing unit comprises;

speech element information selection unit for selecting, for each of prosody candidates including the intermediate prosody, speech element information corresponding to the prosody candidate from the stored speech element information; and

cost calculation unit for calculating, for each of the prosody candidates, a cost value varying according to the degree of naturalness of speech synthesized to have the prosody candidate, based on the selected speech element information, and

the speech synthesizing unit is configured to specify one of the prosody candidates based on the calculated cost values, and execute the speech synthesis process to synthesize speech having the specified prosody candidate based on the speech element information selected for the specified prosody candidate.

3. The speech synthesis system according to claim 2, wherein:

the cost value is a value that increases as the degree to which the degree of naturalness is lower than the reference value becomes higher ; and

the speech synthesizing unit is configured to specify a prosody candidate having the highest degree of similarity to the requested prosody among the prosody candidates the calculated cost values of which are smaller than a predetermined threshold.

4. The speech synthesis system according to claim 3, wherein the speech synthesizing unit is configured to set the threshold on the basis of a maximum value and a minimum value of the calculated cost values.

5. The speech synthesis system according to claim 3, wherein:

the cost calculation unit is configured to acquire the prosody candidates one by one in descending order from the prosody candidate having the highest similarity to the requested prosody and calculate the cost value for the acquired prosody candidate; and

the speech synthesizing unit is configured to, when the calculated cost value becomes smaller than the threshold, specify the prosody candidate for which the cost value has been calculated, and execute the speech synthesis process to synthesize speech having the specified prosody candidate, based on the speech element information selected for the specified prosody candidate.

6. The speech synthesis system according to claim 1, wherein the reference prosody is prosody estimated by executing a language analysis process on a text.

7. The speech synthesis system according to claim 1, wherein the reference prosody and the requested prosody each include at least one of a parameter representing phonetic height, a parameter representing phonetic length, and a parameter representing phonetic magnitude

8. A speech synthesis method comprising:

in the case that speech element information representing a speech element capable of synthesizing speech having a degree of naturalness indicating a degree of similarity to speech uttered by a human higher than a predetermined reference value, when the speech element is used for synthesizing speech having reference prosody which is prosody serving as a reference, is stored in a storage device,

accepting requested prosody information representing requested prosody which is prosody requested by a user;

generating intermediate prosody information representing intermediate prosody which is prosody between the reference prosody and the requested prosody; and

executing a speech synthesis process to synthesize speech based on the generated intermediate prosody information and the stored speech element information.

9. The speech synthesis method according to claim 8, comprising:

selecting, for each of prosody candidates including the intermediate prosody, speech element information corresponding to the prosody candidate from the stored speech element information;

calculating, for each of the prosody candidates, a cost value varying according to the degree of naturalness of speech synthesized to have the prosody candidate, based on the selected speech element information; and

specifying one of the prosody candidates based on the calculated cost values, and executing the speech synthesis process to synthesize speech having the specified prosody candidate based on the speech element information selected for the specified prosody candidate.

10. The speech synthesis method according to claim 9, wherein:

the cost value is a value increasing as the degree to which the degree of naturalness is lower than the reference value becomes higher; and

the speech synthesis method is designed to specify a prosody candidate having the highest degree of similarity to the requested prosody among the prosody candidates the calculated cost values of which are smaller than a predetermined threshold.

11. A computer-readable medium storing a speech synthesis program comprising instructions for causing an information processing device to realize:

speech element information storing process unit for storing in a storage device speech element information representing a speech element capable of synthesizing speech having a degree of naturalness indicating a degree of similarity to speech uttered by a human higher than a predetermined reference value when the speech element is used for synthesizing speech having reference prosody which is prosody serving as a reference;

requested prosody information accepting unit for accepting requested prosody information representing requested prosody which is prosody requested by a user;

intermediate prosody information generating unit for generating intermediate prosody information representing intermediate prosody which is prosody between the reference prosody and the requested prosody; and

speech synthesizing unit for executing a speech synthesis process to synthesize speech based on the generated intermediate prosody information and the stored speech element information.

12. The computer-readable medium according to claim 11, wherein:

the speech synthesizing unit comprises;

speech element information selection unit for selecting, for each of the prosody candidates including the intermediate prosody, speech element information corresponding to the prosody candidate from the stored speech element information; and

cost calculation unit for calculating, for each of the prosody candidates, a cost value varying according to the degree of naturalness of speech synthesized to have the prosody candidate, based on the selected speech element information; and

the speech synthesizing unit is configured to specify one of the prosody candidates based on the calculated cost values, and execute the speech synthesis process to synthesize speech having that prosody candidate, based on the speech element information selected for the specified prosody candidate.

13. The computer-readable medium according to claim 12, wherein:

the cost value is a value that increases as the degree to which the degree of naturalness is lower than the reference value becomes higher; and

the speech synthesizing unit is configured to specify a prosody candidate having the highest degree of similarity to the requested prosody among the prosody candidates the calculated cost values of which are smaller than the predetermined threshold.

14. A speech synthesis system comprising:

speech element information storage means for storing speech element information representing a speech element capable of synthesizing speech having a degree of naturalness indicating a degree of similarity to speech uttered by a human higher than a predetermined reference value when the speech element is used for synthesizing speech having reference prosody which is prosody serving as a reference;

requested prosody information accepting means for accepting requested prosody information representing requested prosody which is prosody requested by a user;

intermediate prosody information generating means for generating intermediate prosody information representing intermediate prosody which is prosody between the reference prosody and the requested prosody; and

speech synthesizing means for executing a speech synthesis process to synthesize speech based on the generated intermediate prosody information and the stored speech element information.