SPEECH RECOGNITION SYSTEM WITH AN ACCURATE RECOGNITION FUNCTION

Abstract: A speech registration/recognition processing sec­ tion (102, 104) is responsive to a speech input signal from a microphone (101) to selectively subject the speech input signal to a registration or a recognition processing, in which upon the registration processing the speech input signal is allowed to be stored as re­ cognition data and upon the recognition processing the speech input signal is compared to the recognition data stored. A speech record/reproduction processing sec­ tion (103, 105) is responsive to the speech input signal from the microphone to subject the speech input signal to a record/reproduction processing, in which upon the record processing the speech input signal is recorded as a record signal and upon the reproduction processing the record signal is delivered as a reproduction signal. A control section (107), in accordance with the registra­ tion or the recognition mode designation signal, is pro­ vided for setting the speech registration/recognition processing section (102, 104) to the registration or the recognition processing and for setting speech record/­ reproduction processing section (103, 105) to the record or the reproduction processing corresponding to the reg­ istration or the re-cognition processing at which the speech registration/recognition processing section (102, 104) is placed.

Description: This invention relates to a speech recognition system with an accurate recognition function, and in particular, to a system as one kind of data input means with an accurate recognition function which can eliminate any recognition error. A conventional speech recognition system of this type comprises a microphone for inputting speech, a speech recognition circuit for registering and recognizing the speech input signal from the microphone, a central processing unit (CPU) for reading a recognition output from the speech recognition circuit and allowing data corresponding to the recognition data to be transmitted to a speech synthesizer via a data bus, a speech synthesizer for receiving data from the CPU and synthesizing said speech from the data, and a speaker for outputting said speech which is synthesized by the speech synthesizer. According to this system, the user can input data and give an instruction without using his hands, and in fact, it proves very useful when applied to an input means. In this system, however, whether or not the recognition output from the speech recognition circuit is wrong is ascertained by the output of the speech synthesizer. Only predetermined speech patterns are written with respect to the speech synthesizer, placing some restriction upon the speech inputs through the speaker. Since the input speech does not always coincide with the registered speech patterns, it is difficult for the user to ascertain their coincidence. This causes uneasiness in the user. During the speech registration process, it is necessary to register the speech input at a predetermined address position in a memory of the speech recognition circuit, thus involving a cumbersome operation. Furthermore, since with respect to a respective word or clause one kind of speech pattern is registered for comparison with the speech input, even if the same user inputs his own speech, it is not often successfully recognized due to ambient noise and the delicately varying speech input characteristic. Where, in particular, the speech recognition system is employed as an input means for a mobile station such as a moving vehicle, the speech is liable to be varied due to the acoustic circumstances within the narrow confines of the vehicle compartment and the traffic noise on the road, resulting in a poor recognition percentage. Where the speech recognition system is used as the input means for automobile telephones, the telephone set per se never has a speech recognition ascertaining function and, therefore, it is not possible for the user to ascertain that the speech input has been correctly recognized, unless it is sent back from a central station. Prior art document DE-A-31 29 320 discloses a similar speech recognition system comprising microphone means, speech registration/recognition processing means, speaker means, mode designation means, and control means. Further, document WESCON 83 CONFERENCE RECORD, 8th-11th November 1983, San Francisco, pages 11/41-11/43, Western Periodical Co., North Hollywood, US; D. KEELEY: "Voice recognition is user friendly", describes a voice recognition system which recognises the speech of a user and responds vocally with a speech recorded from the user. It is an object of the invention to provide a new and improved telephone apparatus with a speech recognition function, which can momentarily ascertain speech input on the basis of speech patterns initially registered at the time of registration and can register speech input in a memory at any desired address position, thus assuring ease of operation by the user. To solve this object the present invention provides a telephone apparatus as stated in the claim. These and other objects and features of this invention can be understood through the following embodiments by reference to the accompanying Figure which is a block diagram showing a speech recognition system according to an embodiment of this invention. The Figure shows, as an embodiment of this invention, the major section of a speech recognition system having the function of positively recognizing spoken word when it is affected by the manner of speaking as well as by the circumstances under which it is spoken. The speech recognition system includes a plurality of speech recognition circuits 211... 21n and a corresponding number of variable characteristic circuits 251... 25n. Speech recognition circuits 211... 21n are connected to speech registration RAM's 221... 22n, where a plurality of modified speech patterns are stored for each word or each clause. The modified speech patterns include, as the characteristics of the speech, the magnitudes of sound volumes, the varying lengths of sounds, the variation of sound intervals, the husky or somewhat masked voices, and so on. The variable characteristic circuit (251... or 25n) is comprised of an amplifier (A11... or A1n) of a different amplification factor and different bandpath characteristic, set of resistors (R11 and R21,... or R1n and R2n) of 2 : 1 values and mode designating switch (S11... or S1n) to allow the speech which is input through microphone 210 in a speech registration mode to be prepared as a variation pattern so that it is stored as such in speech recognition circuit (211... or 21n). When the speech is to be registered, variable characteristic circuits 251... 25n and speech recognition circuits 211... 21n are set to speech registration modes with mode designation switches S11... S1n set to the speech registration mode. In this state, if the user inputs a desired word through microphone 210 by saying the object word to be recognized, then the speech signal is branched to variable characteristic circuits 251... 25n where the branched speeches are modified in accordance with their amplification factor and bandpath characteristic. If, for example, the word "one" is input through the microphone, then the sound characteristics, such as the volume, length, interval and quality for "one", are subjected to modification processing. That is, the variable characteristic circuits 251... 25n prepare n kinds of speech patterns which are obtained through the arbitrary modification of the sound characteristics for "one." The respective modification speech signal is supplied to speech recognition circuits 211... 21n so that they may be stored in speech registration RAM's 221... 22n. In this way, the speech patterns are registered for one word. The other words and clauses are so registered in exactly the same way. When a speech registration is to be made in this system, the mode designation switches S11... S1n are set to the speech registration mode REGIST. When the user inputs his speech through microphone 210 it is, after being branched, supplied respectively through variable characteristic circuits 251... 25n to speech recognition circuits 211... 21n where the aforementioned input speeches are compared to the speech patterns which have been registered in the respective RAM's 221... 22n. The results of comparison are fed via data bus 230a to CPU 230 where the speech recognition processing is performed based on the results of comparison. If, for example, the input speech coincides with any one of the registered speech patterns as the result of comparison, the input speech is recognized from the coincidence data. According to this embodiment, since the input speech is compared to the plurality of modified speech patterns through speech recognition circuits 211... 21n, the speech input can be recognized with a high probability even if it is somewhat modified due to, for example, the illness of the user or the ambient noise. Even if the user employs this system on a mobile station such as an automobile where the quality etc., of his speech is adversely affected, the speech input can be recognized with a high recognition percentage in spite of the degraded acoustic environments and noise in the moving vehicle. Through variable characteristic circuits 251... 25n corresponding to speech recognition circuits 211... 21n, the user has only to input a word or clause, one unit afer another, by speaking, as in the case of the conventional system, making it easier for the user to perform a speech registration operation. Although a plurality of modified speech patterns are prepared for registration through the utilization of variable characteristic circuits 251... 25n for speech recognition circuits 211... 21n, the user can input modified speeches directly through microphone 210 without utilizing the variable characteristic circuits. With respect to the number and kinds of modified speeches, their registering means, their speech recognizing means, etc., can be changed or modified within the spirit and scope of this invention.

Claims: A speech recognition system comprising: microphone means (210) for producing speech input signals of various users, to be registered or recognized; speech recognition and registration means (211, 221; 212, 222, ...) responsive to a speech input signal from the microphone means (210), so as to subject the speech input signal to either a registration or a recognition processing, in which upon the registration processing, the speech input signal is allowed to be stored as recognition data and upon the recognition processing, the speech input signal is compared to the recognition data which has been stored; and a central processing unit (230) which performs speech recognition processing based on the results of comparison, characterized in that: said speech recognition and registration means includes a plurality of speech recognition circuits (211, ..., 21n) which are connected between a corresponding number of variable characteristic circuits (251, ..., 25n) and speech registration RAM's (221, ..., 22n), respectively where a plurality of modified speech patterns are stored for each word or each clause, said modified speech patterns including, as the characteristics of the speech, the magnitudes of sound volumes, the varying lengths of sounds, the variation of sound intervals, the husky or somewhat masked voices, and said variable characteristic circuits (251, ... or 25n) are comprised of an amplifier (A11, ... or A1n) of a different amplification factor and different bandpath characteristic, set of resistors (R11 and R21, ... or R1n and R2n) and a mode designating switch (S11, ... or S1n), respectively, to allow the speech which is input through said microphone (210) in a speech registration mode to be prepared as a variation pattern so that it is stored as such in the speech registration RAM of the corresponding speech recognition circuit (211, ... or 21n), wherein: when a user inputs his speech through said microphone (210) it is supplied respectively through said variable characteristic circuits (251, ..., 25n) to said speech recognition circuits (211, ..., 21n) where the input speeches are compared to the speech patterns which have been registered in the respective speech registration RAM's (221, ..., 22n).

Inventors: ISHII, TAKAAKI PATENT DIV., TOSHIBA K.K., KUGE, TORU PATENT DIV., TOSHIBA K.K.
Applicants: KABUSHIKI KAISHA TOSHIBA
Application year: 1986
Main classification: G10L5
IPC codes: H04M1, G10L15