Speech synthesis apparatus and speech synthesis method

• US 20060136213A1
• Filed: 02/13/2006
• Published: 06/22/2006
• Est. Priority Date: 10/13/2004
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hirose, Yoshifumi, Kamai, Takahiro, Saito, Natsuki
• Granted Patent: US 7,349,847 B2
• Time in Patent Office: Days
• US Class Current: 704/260
• CPC Class Codes: G10L 13/033 Voice editing, e.g. manipulating the voice of the synthesiser
• CPC Class Codes: G10L 13/04 Details of speech synthesis systems, e.g. synthesiser structure or memory management

Abstract

A speech synthesis apparatus which can appropriately transform a voice characteristic of a speech is provided. The speech synthesis apparatus includes an element storing unit in which speech elements are stored, a function storing unit in which transformation functions are stored, an adaptability judging unit which derives a degree of similarity by comparing a speech element stored in the element storing unit with an acoustic characteristic of the speech element used for generating a transformation function stored in the function storing unit, and a selecting unit and voice characteristic transforming unit which transforms, for each speech element stored in the element storing unit, based on the degree of similarity derived by the adaptability judging unit, a voice characteristic of the speech element by applying one of the transformation functions stored in the function storing unit.

Claims

1. A speech synthesis apparatus which synthesizes a speech using speech elements so as to transform a voice characteristic of the speech, said apparatus comprising:

an element storing unit in which speech elements are stored;

a function storing unit in which transformation functions for respectively transforming voice characteristics of the speech elements are stored;

a similarity deriving unit operable to derive a degree of similarity by comparing an acoustic characteristic of one of the speech elements stored in said element storing unit with an acoustic characteristic of a speech element used for generating one of the transformation functions stored in said function storing unit; and

a transforming unit operable to apply, based on the degree of similarity derived by said similarity deriving unit, one of the transformation functions stored in said function storing unit to a respective one of the speech elements stored in said element storing unit, and to transform the voice characteristic of the speech element.

2. The speech synthesis apparatus according to claim 1,

wherein said similarity deriving unit is operable to derive a degree of similarity that is higher the more the acoustic characteristic of the speech element stored in said element storing unit resembles the acoustic characteristic of the speech element used for generating the transformation function, and

said transforming unit is operable to apply, to the speech element stored in said element storing unit, a transformation function generated using a speech element having the highest degree of similarity.

3. The speech synthesis apparatus according to claim 2,

wherein said similarity deriving unit is operable to derive a dynamic degree of similarity based on a degree of similarity between a) an acoustic characteristic of a series that is made up of the speech element stored in said element storing unit and speech elements before and after the speech element, and b) an acoustic characteristic of a series that is made up of the speech element used for generating the transformation function and speech elements before and after the speech element.

4. The speech synthesis apparatus according to claim 2,

wherein said similarity deriving unit is operable to derive a static degree of similarity based on the degree of similarity between the acoustic characteristic of the speech element stored in said element storing unit and the acoustic characteristic of the speech element used for generating the transformation function.

5. The speech synthesis apparatus according to claim 1,

wherein said transforming unit is operable to apply, to the speech element stored in said element storing unit, a transformation function generated using a speech element so that the degree of similarity is a predetermined threshold or more.

6. The speech synthesis apparatus according to claim 1, further comprising

a generating unit operable to generate prosody information indicating a phoneme and a prosody corresponding to a manipulation by a user,

wherein said transforming unit includes:

a selecting unit operable to complementarily select, based on the degree of similarity, a speech element and a transformation function respectively from said element storing unit and said function storing unit, the speech element and the transformation function corresponding to the phoneme and prosody indicated in the prosody information; and

an applying unit operable to apply the selected transformation function to the selected speech element.

7. The speech synthesis apparatus according to claim 6, further comprising

a voice characteristic designating unit operable to receive a voice characteristic designated by the user,

wherein said selecting unit is operable to select a transformation function for transforming a voice characteristic of the speech element into the voice characteristic received by said voice characteristic designating unit.

8. The speech synthesis apparatus according to claim 6,

wherein said generating unit is operable to generate the prosody information by obtaining text data based on the manipulation by the user and estimating a prosody from a phoneme included in the text data.

9. The speech synthesis apparatus according to claim 1, further comprising

a generating unit operable to generate prosody information indicating a phoneme and a prosody corresponding to a manipulation by a user,

wherein said transforming unit includes:

a function selecting unit operable to select, from said function storing unit, a transformation function corresponding to the phoneme and prosody indicated in the prosody information;

an element selecting unit operable to select, based on the degree of similarity, from said element storing unit, a speech element corresponding to the phoneme and prosody indicated in the prosody information for the selected transformation function; and

an applying unit operable to apply the selected transformation function to the selected speech element.

10. The speech synthesis apparatus according to claim 1, further comprising

a generating unit operable to generate prosody information indicating a phoneme and a prosody corresponding to a manipulation by a user,

wherein said transforming unit includes:

an element selecting unit operable to select, from said element storing unit, a speech element corresponding to the phoneme and prosody indicated in the prosody information;

a function selecting unit operable to select, based on the degree of similarity, from said function storing unit, a transformation function corresponding to the phoneme and prosody indicated in the prosody information for the selected speech element selected; and

an applying unit operable to apply the selected transformation function to the selected speech element.

11. The speech synthesis apparatus according to claim 1,

wherein in said element storing unit, speech elements which make up a speech of a first voice characteristic are stored,

in said function storing unit, the following are stored in association with one another for each speech element of the speech of the first voice characteristic:

the speech element;

a standard representative value indicating an acoustic characteristic of the speech element; and

a transformation function for the standard representative value,

said speech synthesis apparatus further comprises

a representative value specifying unit operable to specify, for each speech element of the speech of the first voice characteristic stored in said element storing unit, a representative value indicating an acoustic characteristic of the speech element,

said similarity deriving unit is operable to derive a degree of similarity by comparing the representative value indicated by the speech element stored in said element storing unit with the standard representative value of the speech element used for generating the transformation function stored in said function storing unit, and

said transforming unit includes;

a selecting unit operable to select, for each speech element stored in said element storing unit, from among the transformation functions stored in said function storing unit by being associated with a speech element that is same as the current speech element, a transformation function that is associated with a standard representative value having the highest degree of similarity with the representative value of the current speech element; and

a function applying unit operable to apply, for each speech element stored in said element storing unit, the transformation function selected by said selecting unit to the speech element, and to transform the speech of the first voice characteristic into a speech of a second voice characteristic.

12. The speech synthesis apparatus according to claim 11, further comprising

a speech synthesizing unit operable to:

obtain text data;

generate the speech elements indicating same details as the text data; and

store the speech elements into said element storing unit.

13. The speech synthesis apparatus according to claim 12,

wherein said speech synthesizing unit includes:

an element representative value storing unit in which each speech element which makes up the speech of the first voice characteristic and a representative value of the acoustic characteristic of the speech element are stored in association with one another;

an analyzing unit operable to obtain and analyze the text data; and

a selection storing unit operable to select, based on an analysis result acquired by said analyzing unit, the speech element corresponding to the text data from said element representative value storing unit, and to store, into said element storing unit, the selected speech element and the representative value of the selected speech element by being associated with one another, and

said representative value specifying unit is operable to specify, for each speech element stored in said element storing unit, a representative value stored in association with the speech element.

14. The speech synthesis apparatus according to claim 13, further comprising:

a standard representative value storing unit in which the following is stored for each speech element of the speech of the first voice characteristic;

the speech element; and

a standard representative value indicating an acoustic characteristic of the speech element;

a target representative value storing unit in which the following is stored for each speech element of the speech of the second voice characteristic;

the speech element; and

a target representative value showing an acoustic characteristic of the speech element; and

a transformation function generating unit operable to generate, the transformation function corresponding to the standard representative value, based on the standard representative value and target representative value corresponding to the same speech element that are respectively stored in said standard representative value storing unit and said target representative value storing unit.

15. The speech synthesis apparatus according to claim 14,

wherein the speech element is a phoneme, and

the representative value and standard representative value indicating the acoustic characteristics are values of formant frequencies at a time center of the phoneme.

16. The speech synthesis apparatus according to claim 14,

wherein the speech element is a phoneme, and

the representative value and standard representative value indicating the acoustic characteristics are respectively average values of the formant frequencies of the phoneme.

17. A speech synthesizing method for synthesizing a speech using speech elements so as to transform a voice characteristic of the speech,

wherein in the element storing unit, speech elements are stored, and

in the function storing unit, transformation functions for transforming voice characteristics of the respective speech elements are stored,

said speech synthesizing method comprises:

deriving a degree of similarity by comparing an acoustic characteristic of one of the speech elements stored in said element storing unit with an acoustic characteristic of a speech element used for generating one of the transformation functions stored in said function storing unit; and

applying, based on the degree of similarity derived in said deriving, one of the transformation functions stored in said function storing unit to a respective one of the speech elements stored in said element storing unit, and transforming the voice characteristic of the speech element.

18. A program for synthesizing a speech using speech elements so as to transform a voice characteristic of the speech,

wherein in the element storing unit, speech elements are stored, and

in the function storing unit, transformation functions for transforming voice characteristics of the respective speech elements are stored,

said program causing a computer to execute:

deriving a degree of similarity by comparing an acoustic characteristic of one of the speech elements stored in said element storing unit with an acoustic characteristic of a speech element used for generating one of the transformation functions stored in said function storing unit; and

applying, based on the degree of similarity derived in said deriving, one of the transformation functions stored in said function storing unit to a respective one of the elements stored in said element storing unit, and transforming the voice characteristic of the speech element.