# US 9,520,125 B2 · Speech synthesis device, speech synthesis method, and speech synthesis program > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,520,125 B2 - Document ID: US9520125B2 - Status: Granted - Kind: B2 - Application number: 14/131,409 - Filed: 2012-06-08 - Published: 2014-05-29 - Granted: 2016-12-13 - Earliest claimed: 2011-07-11 - Assignees: NEC Corporation - Applicants: Yasuyuki Mitsui; Masanori Kato; Reishi Kondo - Inventors: Yasuyuki Mitsui; Masanori Kato; Reishi Kondo - Web page: https://patentgrep.com/patent/US9520125B2 ## CPC - G10L 15/08: Speech classification or search - G10L 13/08: Text analysis or generation of parameters for speech synthesis out of text, e.g. grapheme to phoneme translation, prosody generation or stress or intonation determination - G10L 2013/105: {Duration} - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING ## Abstract There are provided a speech synthesis device, a speech synthesis method and a speech synthesis program which can represent a phoneme as a duration shorter than a duration upon modeling according to a statistical method. A speech synthesis device 80 according to the present invention includes a phoneme boundary updating means 81 which, by using a voiced utterance likelihood index which is an index indicating a degree of voiced utterance likelihood of each state which represents a phoneme modeled by a statistical method, updates a phoneme boundary position which is a boundary with other phonemes neighboring to the phoneme. ## Claims ### Claim 1 A speech synthesis device comprising: hardware including a processor, wherein the processor is configured to: by using a voiced utterance likelihood index which is an index indicating a degree of voiced utterance likelihood of each state which represents a phoneme modeled by a statistical method, update a phoneme boundary position which is a boundary with other phonemes neighboring to the phoneme; and calculate a duration of each phoneme based on the updated phoneme boundary position, and generate synthesized speech based on the calculated duration of phoneme, wherein, when a phoneme before and after a phoneme boundary is an unvoiced sound and a voiced sound, the processor is configured to determine whether a state before and after the phoneme boundary indicated a voiced state or an unvoiced state by using the voiced utterance likelihood index, and wherein, when the state before and after the phoneme boundary are both determined as voiced state or an unvoiced state, the processor is configured to update the phoneme boundary position to move in a predetermined direction according to the state. ### Claim 2 (depends on 1) The speech synthesis device according to claim 1, wherein the processor is further configured to specify whether or not each state which represents the phoneme indicates a voiced state or an unvoiced state, and, when one of the neighboring phonemes indicates the unvoiced sound and other one of the phonemes indicates a voiced sound, determine a moving direction of a phoneme boundary position according to a rule set in advance based on a relationship between the voiced state and the unvoiced state. ### Claim 3 (depends on 2) The speech synthesis device according to claim 2, wherein the processor is further configured to specify as the voiced state a state which represents a phoneme when the voiced utterance likelihood index exceeds a threshold set in advance, and specify as the unvoiced state a state which represents a phoneme when the voiced utterance likelihood index is the threshold set in advance or less. ### Claim 4 (depends on 1) The speech synthesis device according to claim 1, wherein the processor is further configured to update the phoneme boundary position based on a difference between voiced utterance likelihood indices of neighboring states. ### Claim 5 (depends on 4) The speech synthesis device according to claim 4, wherein, when the difference between the voiced utterance likelihood index of one of the neighboring states and the voiced utterance likelihood index of the other state exceeds the threshold set in advance, the processor is further configured to determine as the phoneme boundary position a position between the one state and the other state. ### Claim 6 (depends on 1) The speech synthesis device according to claim 1, wherein the processor is further configured to calculate a duration of the phoneme based on the updated phoneme boundary position. ### Claim 7 (depends on 1) The speech synthesis device according to claim 1, wherein the processor is further configured to update the phoneme boundary position in units of a length corresponding to a width of a state. ### Claim 8 (depends on 1) The speech synthesis device according to claim 1, wherein the processor is further configured to determine whether or not the voiced utterance likelihood index of each state is adequate and change the voiced utterance likelihood index which is determined to be inadequate to an adequate value. ### Claim 9 (depends on 8) The speech synthesis device according to claim 8, wherein, when voiced utterance likelihood determination information which is a result of determining the voiced state or the unvoiced state based on the voiced utterance likelihood index is switched two or more times in one phoneme or when the voiced utterance likelihood determination information of a target phoneme indicates information different from phonetic piece information which is information set in advance as information indicating a property of the phoneme, the processor is further configured to determine that the voiced utterance likelihood index is inadequate. ### Claim 10 A speech synthesis method comprising, by using a voiced utterance likelihood index which is an index indicating a degree of voiced utterance likelihood of each state which represents a phoneme modeled by a statistical method, updating a phoneme boundary position which is a boundary with other phonemes neighboring to the phoneme; and calculating a duration of each phoneme based on the updated phoneme boundary position, and generating synthesized speech based on the calculated duration of phoneme, wherein, when a phoneme before and after a phoneme boundary is an unvoiced sound and a voiced sound, determining whether a state before and after the phoneme boundary indicates a voiced state or an unvoiced state by using the voiced utterance likelihood index, and wherein, when the state before and after the phoneme boundary are both determined as voiced state or an unvoiced state, updating the phoneme boundary position to move in a predetermined direction according to the state. ### Claim 11 (depends on 10) The speech synthesis method according to claim 10, further comprising specifying whether or not each state which represents the phoneme indicates a voiced state or an unvoiced state, and, when one of the neighboring phonemes indicates the unvoiced sound and other one of the phonemes indicates a voiced sound, determining a moving direction of a phoneme boundary position according to a rule set in advance based on a relationship between the voiced state and the unvoiced state. ### Claim 12 (depends on 10) The speech synthesis method according to claim 10, further comprising updating the phoneme boundary position based on a difference between voiced utterance likelihood indices of neighboring states. ### Claim 13 A non-transitory computer readable information recording medium storing a speech synthesis program that, when executed by a processor, performs a method for: by using a voiced utterance likelihood index which is an index indicating a degree of voiced utterance likelihood of each state which represents a phoneme modeled by a statistical method, updating a phoneme boundary position which is a boundary with other phonemes neighboring to the phoneme; and calculating a duration of each phoneme based on the updated phoneme boundary position, and generating synthesized speech based on the calculated duration of phoneme, wherein, when a phoneme before and after a phoneme boundary is an unvoiced sound and a voiced sound, determining whether a state before and after the phoneme boundary indicates a voiced state or an unvoiced state by using the voiced utterance likelihood index, and wherein, when the state before and after the phoneme boundary are both determined as voiced state or an unvoiced state, updating the phoneme boundary position to move in a predetermined direction according to the state. ### Claim 14 (depends on 13) The non-transitory computer readable information recording medium according to claim 13, specifying whether or not each state which represents the phoneme indicates a voiced state or an unvoiced state, and, when one of the neighboring phonemes indicates the unvoiced sound and other one of the phonemes indicates a voiced sound, determining a moving direction of a phoneme boundary position according to a rule set in advance based on a relationship between the voiced state and the unvoiced state. ### Claim 15 (depends on 13) The non-transitory computer readable information recording medium according to claim 13, further comprising updating the phoneme boundary position based on a difference between voiced utterance likelihood indices of neighboring states.