Speech synthesis system and its method

A speech synthesis system has a word lexicon stored in a storage device for managing word information, a speech lexicon stored in the storage device for managing speech data. A language processing module carries out language processing of an input text by using the word information, and an acoustic processing module generates a synthesized speech signal by using the speech data in response to a processing result of the language processing module. A D/A converter converts the synthesized speech signal to an analog signal. The system further includes a detection module detecting performance or conditions of a hardware part of a computer in which the system is implemented, and an adjustment module adjusting the word information and/or the speech data which are to be given to the language processing module and the acoustic processing module, based on a detection result of the detection module. Therefore, an optimum speech-synthesis processing suitable for any computer is performed.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to a speech synthesis system and 
its method for generating a synthesized speech signal of an input text, 
and more particularly, to a speech synthesis system and its method in 
which a speech-synthesis processing suitable for a computer use can be 
realized. 
2. Description of the Prior Art 
FIG. 1 shows a whole configuration of a prior art of a computer-implemented 
speech synthesis system. 
In general, the speech synthesis system is constructed with a given 
computer equipped with a D/A converter 5, in which a speech-synthesis 
processing part is installed as the software. And the speech synthesis 
system also comprises a word lexicon 1 storing word information such as a 
representation, a pronunciation, an accent, and part-of-speech information 
of words, and a speech lexicon 2 storing speech data such as a speech 
waveform or speech parameters (e.g. COR factors which characterize a 
speech) each synthesizing part of words. The word lexicon 1 and the speech 
lexicon 2 are represented with second-order storing devices for which 
CD-ROMs or hard disks are commonly used. 
The speech-synthesis processing part as the software comprises a language 
processing module 3 and an acoustic processing module 4. The language 
processing module 3, which carries out the language processing for the 
speech synthesis, includes a morphological analysis module 10, a 
dependency analysis module 11, and a prosodic-symbol generating module 12. 
The acoustic processing module 4, which generates a synthesized speech 
signal, includes a duration decision module 14, a 
fundamental-frequency-pattern generating module 15, and a waveform 
generating module 16. The language processing module 3 also includes a 
word lexicon buffer 13, which temporarily stores a whole or a part of the 
word lexicon 1. The acoustic processing module 4 also includes a speech 
lexicon buffer 17, which temporarily stores a whole or a part of the 
speech lexicon 2. The word lexicon buffer 13 and the speech lexicon buffer 
17 are represented with firstorder storing devices for which random access 
memories (RAM) are commonly used. 
The D/A converter 5 is hardware-constructed to convert a digital signal of 
the synthesized speech signal generated in the acoustic processing module 
4 to an analog signal. 
Next, an operation will be given of the conventional speech synthesis 
system. 
First, the morphological analysis module 10 analyzes a morpheme (word) 
which is a minimum unit in an input text, in order to decide the 
pronunciation of the word and to obtain its accent and part-of-speech 
information, while referring to the word information in the word lexicon 
buffer 13, which is derived from the word lexicon 1. 
Second, the dependency analysis module 11 analyzes a dependency 
(modification) relation in each phrase from the information such as 
part-of-speech information obtained in the morphological analysis module 
10. 
Third, the prosodic-symbol generating module 12 generates prosodic symbols 
indicating the accent and breathers, to finally decide locations of the 
accent of the words by using the accent information and an accent 
connection rule of each word, and to decide locations of the breathers by 
using the dependency information of the phrase. 
Forth, the duration decision module 14 decides a duration of each syllable 
(phoneme) corresponding to the pronunciation. 
Fifth, the fundamental-frequency-pattern generating module 15 generates a 
time variation pattern of a fundamental frequency which is a physical 
value to indicate an intonation and the accent, from the prosodic symbols. 
Sixth, the waveform generating module 16 reads out speech data associated 
with the syllable (phoneme) to be synthesized, from the speech data in the 
speech lexicon buffer 17 derived from the speech lexicon 2, and generates 
the synthesized speech signal based on the duration and the fundamental 
frequency pattern. 
And finally, the D/A converter 5 converts the synthesized speech signal 
generated in the waveform generating module 16 to produce the analog 
audible signal. 
In the speech synthesis system having such a configuration, there is a need 
for the computer having a hardware performance to realize practical speech 
synthesis characteristics (processing speed and a speech quality level). 
In order to realize the practical speech synthesis characteristics, a 
number of the words stored in the word lexicon 1 is required to increase, 
and further a sampling frequency and a number of quantization levels of 
the speech data stored in the speech lexicon 2 are required to increase. 
Also needed is the D/A converter 5 applicable for such improved 
characteristics. 
Therefore, according to the prior art, when a user constructs the speech 
synthesis system, the user has to select the computer having the hardware 
performance which is required by the speech synthesis system. However, the 
user desires that the software of the speech synthesis system be operable 
in the computer being commonly used by the user. 
In addition, to meet different users' requirements, manufacturers also have 
to fabricate a plurality of software capable of realizing a variety of 
speech-synthesis characteristic levels with relation to the hardware 
performance of the different users' computers. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a speech synthesis system and 
its method which is capable of realizing a speech-synthesis processing 
suitable for any computer in which software is run, in which the 
disadvantages described above are eliminated. 
The object described above is achieved by a speech synthesis system having 
a word lexicon stored in a storage device for managing word information, a 
speech lexicon stored in the storage device for managing speech data, a 
language processing module carrying out language processing on an input 
text by using the word information, an acoustic processing module 
generating a synthesized speech signal by using the speech data in 
response to a processing result of the language processing module, and a 
D/A converter converting the synthesized speech signal to an analog 
signal, the system comprising: a detection module detecting performance or 
conditions of a hardware part of a computer in which the system is 
implemented; and an adjustment module adjusting the word information 
and/or the speech data which are to be given to the language processing 
module and the acoustic processing module, based on a detection result of 
the detection module; wherein a speech-synthesis processing suitable for 
any computer is performed. 
The object described above is also achieved by the speech synthesis system 
mentioned above, wherein the detection module comprises a portion or a 
whole of: a CPU-function detection module detecting CPU performance or CPU 
load; a memory-function detection module detecting memory capacity or 
memory using situation; a storage-device-function detection module 
detecting access performance of the storage device; and a 
D/A-converter-function detection module detecting D/A converting 
performance of the D/A converter. 
The object described above is further achieved by the speech synthesis 
system mentioned above, further comprising a bit adjustment module 
adjusting bit data of the synthesized speech signal generated in the 
acoustic processing module according to a number of quantization bits of 
the D/A converter detected by the D/A-converter-function detection module, 
when the number of the quantization bits of the D/A converter is not 
identical to a number of quantization bits of the synthesized speech 
signal generated in the acoustic processing module. 
In addition, the object described above is achieved by the speech synthesis 
system mentioned above, further comprising a frequency adjustment module 
adjusting a sampling frequency of the synthesized speech signal generated 
in the acoustic processing module according to a sampling frequency of the 
D/A converter detected by the D/A-converter-function detection module, 
when the sampling frequency of the D/A converter is not identical to a 
sampling frequency of the synthesized speech signal generated in the 
acoustic processing module. 
The object described above is further achieved by the speech synthesis 
system mentioned above, wherein the adjustment module adjusts the speech 
data for the acoustic processing module, by using means of adjusting a 
number of quantization bits of the speech data, adjusting a sampling 
frequency of the speech data, adjusting an amount of supply of the speech 
data, or combinations thereof. 
And the above speech synthesis system is also constructed with a setting 
module by which a user can set performance or conditions of a hardware 
part of a computer in which the system is implemented, with a dialogic 
processing between the user and the computer, instead of the detection 
module. 
According to the speech synthesis system, according to the hardware 
performance or conditions detected in the detection module, the word 
information directed to the language processing module is adjusted, and 
the number of the quantization bits, the sampling frequency, and the 
amount of supply of the speech data directed to the acoustic processing 
module are adjusted. 
By such adjustment, with the computer having high hardware performance, the 
language processing module and the acoustic processing module may perform 
superior speech-synthesis processing, and with the computer having poor 
hardware performance, these modules may perform optimum speech-synthesis 
processing in the range of that hardware performance. 
In this way, according to the speech synthesis system, the speech-synthesis 
processing suitable for any computer in which software is run, may be 
realized. Thus, the user may construct a good speech synthesis system with 
the computer which has been used by the user.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
First, a description will be given of a principle of a speech synthesis 
system according to the present invention, by referring to FIG. 2. FIG. 2 
shows a basic configuration for explaining the principle of the speech 
synthesis system according to the present invention. This speech synthesis 
system comprises a computer 100 in which a software for the speech 
synthesis system is installed, a word lexicon 1 managing word information, 
and a speech lexicon 2 managing speech data necessary for the 
speech-synthesis processing (e.g. successive data of 48 kHz.times.16 
bits). The word lexicon 1 and the speech lexicon 2 are stored in a 
second-order storage device equipped with the computer 100. In general, a 
CD-ROM or a hard disk is used as the second-order storage device. 
The computer 100 comprises a language processing module 3, an acoustic 
processing module 4, a D/A converter 5, a detection module 6, an 
adjustment module 7, a bit adjustment module 7a, a frequency adjustment 
module 7b, a word-information storage area 8, and a speech-data storage 
area 9, to construct the speech synthesis system. 
The language processing module 3 receives an input text, and performs a 
language processing for the speech synthesis by using the word information 
data which is managed by the word lexicon 1. The acoustic processing 
module 4 receives a processing result of the language processing module 3, 
and generates a synthesized speech signal of the input text by using the 
speech data which is managed by the speech lexicon 2. The D/A converter 5 
converts the synthesized speech signal generated in the acoustic 
processing module to an analog audible signal. 
The detection module 6 detects performance and conditions of the computer 
hardware in which the system's software is run. The detection module 6 
comprises a portion or a whole of a CPU-function detection module 
detecting CPU performance or CPU load, a memory-function detection module 
detecting memory capacity or memory-using situation, a 
second-order-storage-device-function detection module detecting access 
performance of the second-order storage device, and a 
D/A-converter-function detection module detecting D/A converting 
performance of the D/A converter 5. 
The adjustment module 7 adjusts lexicon information directed to the 
language processing module 3 and the acoustic processing module 4 
according to detecting results of the detection module 6. The bit 
adjustment module 7a, connected with an output of the acoustic processing 
module 4, adjusts bit data of the synthesized speech signal generated in 
the acoustic processing module 4 according to a detection result of the 
D/A-converter-function detection module of the detection module 6. The 
frequency adjustment module 7b, also connected with the output of the 
acoustic processing module 4, adjusts a sampling frequency of the 
synthesized speech signal generated in the acoustic processing module 4 
according to the detection result of the D/A-converter-function detection 
module of the detection module 6. 
The word-information storage area 8 stores the word information adjusted by 
the adjustment module 7. This word information stored in the 
wordinformation storage area 8 is accessed by the language processing 
module 3. The speech-data storage area 9 stores the speech data adjusted 
by the adjustment module 7. This speech data stored in the speech-data 
storage area 9 is accessed by the acoustic processing module 4. 
In this system, the detection module 6 detects the CPU performance or the 
CPU load by the CPU-function detection module, detects the memory capacity 
or the memory-using situation by the memory-function detection module, 
detects the access performance of the second-order storage device by the 
second-order-storage-device-function detection module, or detects 
quantization performance and frequency performance of the D/A converter 5 
by the D/A-converter-function detection module. 
When the detection module 6 detects the performance or the conditions of 
the hardware of the computer 100, and the detection result is, for 
example, sufficient memory, the adjustment module 7 reads out a large 
number of the word information from the word lexicon 1 to store in the 
word-information storage area 8. In this way, the word information is 
adjusted by the detection result. If the detection result is sufficient 
CPU performance, the speech data stored in the speech lexicon 2 is sampled 
in a high frequency to store it in the speech-data storage area 9. In this 
way, according to the detection result, a number of quantization bits of 
the speech data is adjusted to store it in the speech-data storage area 9, 
a sampling frequency of the speech data is adjusted to store it in the 
speech-data storage area 9, or an amount of supply of the speech data is 
adjusted to store it in the speech-data storage area 9. Or, by using 
combinations thereof, the speech data directed to the acoustic processing 
module 4 is adjusted. 
The bit adjustment module 7a adjusts bit data of the synthesized speech 
signal generated in the acoustic processing module 4 according to a number 
of quantization bits of the D/A converter 5 detected by the 
D/A-converter-function detection module, when the number of the 
quantization bits of the D/A converter 5 is not identical to the number of 
the quantization bits of the synthesized speech signal generated in the 
acoustic processing module 4. 
The frequency adjustment module 7b adjusts the sampling frequency of the 
synthesized speech signal generated in the acoustic processing module 4 
according to a sampling frequency of the D/A converter detected by the 
D/A-converter-function detection module, when the sampling frequency of 
the D/A converter is not identical to the sampling frequency of the 
synthesized speech signal generated in the acoustic processing module 4. 
By such adjustment, with the computer having high hardware performance, the 
language processing module 3 and the acoustic processing module 4 may 
perform superior speech-synthesis processing, and with the computer having 
poor hardware performance, these modules 3, 4 may perform optimum 
speech-synthesis processing in the range of that hardware performance. 
And, FIG. 3 shows a basic configuration for explaining a principle of 
another speech synthesis system according to the present invention. A 
configuration of this system is almost similar to that of the system in 
FIG. 2, but a setting module 6' is installed in the computer instead of 
the detection module 6. By using the setting module 6', a user can set the 
performance or conditions of the hardware part of the computer 100, with a 
dialogic processing between the user and the computer 100. Other 
operations are the same as the system of FIG. 2. In this system, there is 
a flexibility that the performance or the conditions of the computer 
hardware may be adjusted by the user. 
Next, descriptions will be given of embodiments of the speech synthesis 
system according to the present invention, by referring to FIGS. 4 to 7. 
FIGS. 4 to 7 show examples of configurations of the speech synthesis 
system in the case that a CPU-function detection module 60 is used in the 
detection module 6. A block shown as a reference numeral 90 represents a 
data buffer corresponding to the speech-data storage area 9. 
The CPU-function detection module 60 detects the CPU performance or the CPU 
load by means of, for example, running a test program and detecting its 
running time. Or the module 60 detects the CPU performance of a 32-bit 
machine by querying it to an operating system. These detecting results are 
processed to be represented with given levels. 
In the embodiment of FIG. 4, the system includes a plurality of speech 
lexicons 2-i (i=1 to n) which manage the speech data having different 
sampling frequencies. And the adjustment module 7 consists of a 
sampling-frequency decision module 700 and a speech-lexicon selection 
module 701. 
In the embodiment of FIG. 4 constructed in such a structure, once the 
CPU-function detection module 60 detects the CPU performance or the CPU 
load, and produces the level of the detection result, the 
sampling-frequency decision module 700 decides the sampling frequency of 
the speech data based on the level detected in the CPU-function detection 
module 60. For example, when the detection result of the level which 
indicates high CPU performance is given from the CPU-function detection 
module 60, the sampling-frequency decision module 700 decides to use the 
speech data having a high sampling frequency such as 48 kHz because of the 
high processing performance, whereas when the detection result of the 
level which indicates low CPU performance is given, the module 700 decides 
to use the speech data having a low sampling frequency such as 8 kHz 
because of the low processing performance. 
And subsequently, the speech-lexicon selection module 701 receives the 
decision result of the sampling-frequency decision module 700, and reads 
out the speech data from the speech lexicon 2-i which manages the speech 
data having a decided sampling frequency, the speech data read out being 
stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 4, by means of changing the sampling 
frequency of the speech data stored in the speech-data buffer 90 based on 
the CPU performance, the speech-synthesis processing suitable for the CPU 
performance may be realized by adjusting the amount of the speech data 
directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 5, the system includes the 
single speech lexicon 2 which manages the speech data having the high 
sampling frequency of, for example, 48 kHz. The adjustment module 7 
consists of the sampling-frequency decision module 700 and a down-sampling 
processing module 702. 
In the embodiment of FIG. 5, once the CPU-function detection module 60 
detects the CPU performance or the CPU load, and produces the level of the 
detection result, the sampling-frequency decision module 700 decides the 
sampling frequency of the speech data based on the value of the level, as 
described above. 
And subsequently, the down-sampling processing module 702 receives the 
decision result of the sampling-frequency decision module 700, and derives 
the speech data from the speech lexicon to store it in the speech-data 
buffer 90 in a suitable sampling-frequency. For example, when the 
sampling-frequency decision module 700 decides the high sampling frequency 
such as 48 kHz, the down-sampling processing module 702 reads out directly 
the speech data stored in the speech lexicon 2, and stores it in the 
speech-data buffer 90. When the sampling-frequency decision module 700 
decides a low sampling frequency such as 16 kHz, the down-sampling 
processing module 702 reads out the speech data stored in the speech 
lexicon 2 with down-sampling to 16 kHz, and stores it in the speech-data 
buffer 90. 
Thus, in the embodiment of FIG. 5, by means of changing the sampling 
frequency of the speech data stored in the speech-data buffer 90 based on 
the CPU performance, the speech-synthesis processing suitable for the CPU 
performance may be realized by adjusting the amount of the speech data 
directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 6, the system includes the 
plurality of the speech lexicons 2-i (i=1 to n) which manage the speech 
data having different numbers of the quantization bits. And the adjustment 
module 700 consists of a quantization-bit decision module 703 and the 
speech-lexicon selection module 701. 
In the embodiment of FIG. 6 constructed in such a structure, once the 
CPU-function detection module 60 detects the CPU performance or the CPU 
load, and produces the level of the detection result, the quantization-bit 
decision module 703 decides the number of the quantization bits of the 
speech data based on the level detected in the CPU-function detection 
module 60. For example, when the detection result of the level which 
indicates high CPU performance is given from the CPU-function detection 
module 60, the quantization-bit decision module 703 decides to use the 
speech data having large quantization bits such as 16 bits because of the 
high processing performance, whereas when the detection result of the 
level which indicates low CPU performance is given, the module 703 decides 
to use the speech data having small quantization bits such as 8 bits 
because of the low processing performance. 
And subsequently, the speech-lexicon selection module 701 receives the 
decision result of the quantization-bit decision module 703, and reads out 
the speech data from the speech lexicon 2-i which manages the speech data 
having a decided quantization-bit number, the speech data read out being 
stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 6, by means of changing the number of the 
quantization bits of the speech data stored in the speech-data buffer 90 
based on the CPU performance, the speech-synthesis processing suitable for 
the CPU performance may be realized by adjusting the amount of the speech 
data directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 7, the system includes the 
single speech lexicon 2 which manages the speech data having the large 
number of the quantization bits, for example, 16 bits. The adjustment 
module 7 consists of the quantization-bit decision module 703 and a 
quantization-bit changing module 704. 
In the embodiment of FIG. 7, once the CPU-function detection module 60 
detects the CPU performance or the CPU load, and produces the level of the 
detection result, the quantization-bit decision module 703 decides the 
number of the quantization bits of the speech data based on the value of 
the level, as described above. 
And subsequently, the quantization-bit changing module 704 receives the 
decision result of the quantization-bit decision module 703, and derives 
the speech data from the speech lexicon 2 to store it in the speech-data 
buffer 90 in a suitable quantization-bit number. For example, when the 
quantization-bit decision module 703 decides the number of the 
quantization bits is 16 bits, the quantization-bit changing module 704 
reads out directly the speech data stored in the speech lexicon 2, and 
stores it in the speech-data buffer 90. When the quantization-bit decision 
module 703 decides the number of the quantization bits is 8 bits, the 
quantization-bit changing module 704 reads out the speech data stored in 
the speech lexicon 2, changes it to 8-bit quantization, and stores it in 
the speech-data buffer 90. 
Thus, in the embodiment of FIG. 7, by means of changing the number of the 
quantization bits of the speech data stored in the speech-data buffer 90 
based on the CPU performance, the speech-synthesis processing suitable for 
the CPU performance may be realized by adjusting the amount of the speech 
data directed to the acoustic processing module 4. 
As described above, in the embodiments of FIGS. 4 to 7, the 
speech-synthesis processing suitable for the CPU performance may be 
realized by adjusting the amount of the speech data directed to the 
acoustic processing module 4 according to the detection result of the 
CPU-function detection module 60. Further, according to the detection 
result of the CPU-function detection module 60, by adjusting the amount of 
the speech data directed to the language processing module 3, the 
speech-synthesis processing suitable for the CPU performance may be also 
realized. 
Next, descriptions will be given of other embodiments of the speech 
synthesis system according to the present invention, by referring to FIGS. 
8 to 16. FIGS. 8 to 16 show examples of configurations of the speech 
synthesis system in the case that a memory-function detection module 61 is 
used in the detection module 6. A block shown as a reference numeral 80 
represents a word-information buffer corresponding to the word-information 
storage area 8. 
The memory-function detection module 61 detects the memory capacity or the 
memory-using situation by means of, for example, querying the operating 
system. These detecting results are processed to be represented with given 
levels. 
In the embodiment of FIG. 8, this system includes the plurality of speech 
lexicons 2-i (i=1 to n) which manage the speech data having different 
sampling frequencies. And the adjustment module 7 consists of the 
sampling-frequency decision module 700 and the speech-lexicon selection 
module 701. 
In the embodiment of FIG. 8 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the sampling-frequency decision module 700 decides the sampling frequency 
of the speech data based on the level detected in the memory-function 
detection module 61. For example, when the detection result of the level 
which indicates high memory performance is given from the memory-function 
detection module 61, the sampling-frequency decision module 700 decides to 
use the speech data having the sampling frequency of, for example, 48 kHz, 
because of a sufficient memory, whereas when the detection result of the 
level which indicates low memory performance is given, the module 700 
decides to use the speech data having the sampling frequency of, for 
example, 16 kHz, because of a small memory. 
And subsequently, the speech-lexicon selection module 701 receives the 
decision result of the sampling-frequency decision module 700, and reads 
out the speech data from the speech lexicon 2-i which manages the speech 
data having a decided sampling frequency, the speech data read out being 
stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 8, by means of changing the sampling 
frequency of the speech data stored in the speech-data buffer 90 based on 
the memory performance, the speech-synthesis processing suitable for the 
memory performance may be realized by adjusting the amount of the speech 
data directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 9, the system includes the 
single speech lexicon 2 which manages the speech data having the high 
sampling frequency of, for example, 48 kHz. The adjustment module 7 
consists of the sampling-frequency decision module 700 and the 
down-sampling processing module 702. 
In the embodiment of FIG. 9, once the memory-function detection module 61 
detects the memory capacity or the memory-using situation, and produces 
the level of the detection result, the sampling-frequency decision module 
700 decides the sampling frequency of the speech data based on the value 
of the level, as described above. 
And subsequently, the down-sampling processing module 702 receives the 
decision result of the sampling-frequency decision module 700, and derives 
the speech data from the speech lexicon to store it in the speech-data 
buffer 90 in the suitable sampling frequency. For example, when the 
sampling-frequency decision module 700 decides the high sampling frequency 
such as 48 kHz, the down-sampling processing module 702 reads out directly 
the speech data stored in the speech lexicon 2, and stores it in the 
speech-data buffer 90. When the sampling-frequency decision module 700 
decides the low sampling frequency such as 16 kHz, the down-sampling 
processing module 702 reads out the speech data stored in the speech 
lexicon 2 with down-sampling to 16 kHz, and stores it in the speech-data 
buffer 90. 
Thus, in the embodiment of FIG. 9, by means of changing the sampling 
frequency of the speech data stored in the speech-data buffer 90 based on 
the memory performance, the speech-synthesis processing suitable for the 
memory performance may be realized by adjusting the amount of the speech 
data directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 10, the system includes the 
plurality of the speech lexicons 2-i (i=1 to n) which manage the speech 
data having different numbers of the quantization bits. And the adjustment 
module 700 consists of the quantization-bit decision module 703 and the 
speech-lexicon selection module 701. 
In the embodiment of FIG. 10 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the quantization-bit decision module 703 decides the number of the 
quantization bits of the speech data based on the level detected in the 
memory-function detection module 61. For example, when the detection 
result of the level which indicates the high memory performance is given 
from the memory-function detection module 61, the quantization-bit 
decision module 703 decides to use the speech data having large 
quantization bits such as 16 bits because of the sufficient memory, 
whereas when the detection result of the level which indicates the low 
memory performance is given, the module 703 decides to use the speech data 
having small quantization bits such as 8 bits because of the small memory. 
And subsequently, the speech-lexicon selection module 701 receives the 
decision result of the quantization-bit decision module 703, and reads out 
the speech data from the speech lexicon 2-i which manages the speech data 
having the decided quantization-bit number, the speech data read out being 
stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 10, by means of changing the number of the 
quantization bits of the speech data stored in the speech-data buffer 90 
based on the memory performance, the speech-synthesis processing suitable 
for the memory performance may be realized by adjusting the amount of the 
speech data directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 11, the system includes the 
single speech lexicon 2 which manages the speech data having the large 
number of the quantization bits, for example, 16 bits. The adjustment 
module 7 consists of the quantization-bit decision module 703 and the 
quantization-bit changing module 704. 
In the embodiment of FIG. 11, once the memory-function detection module 61 
detects the memory capacity or the memory-using situation, and produces 
the level of the detection result, the quantization-bit decision module 
703 decides the number of the quantization bits of the speech data based 
on the value of the level, as described above. 
And subsequently, the quantization-bit changing module 704 receives the 
decision result of the quantization-bit decision module 703, and derives 
the speech data from the speech lexicon 2 to store it in the speech-data 
buffer 90 in the suitable quantization-bit number. For example, when the 
quantization-bit decision module 703 decides the number of the 
quantization bits is 16 bits, the quantization-bit changing module 704 
reads out directly the speech data stored in the speech lexicon 2, and 
stores it in the speech-data buffer 90. When the quantization-bit decision 
module 703 decides the number of the quantization bits is 8 bits, the 
quantization-bit changing module 704 reads out the speech data stored in 
the speech lexicon 2, changes it to 8-bit quantization, and stores it in 
the speech-data buffer 90. 
Thus, in the embodiment of FIG. 11, by means of changing the number of the 
quantization bits of the speech data stored in the speech-data buffer 90 
based on the memory performance, the speech-synthesis processing suitable 
for the memory performance may be realized by adjusting the amount of the 
speech data directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 12, this system includes the 
single speech lexicon 2, and the adjustment module 7 consists of a 
plurality of speech-lexicon indexes 705-i (i=1 to m), a 
speech-lexicon-index selection module 706, and a speech-lexicon-download 
control module 707. 
In the embodiment of FIG. 12 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the speech-lexicon-index selection module 706 decides the speech-lexicon 
index 705-i to be utilized based on the level detected in the 
memory-function detection module 61. For example, when the detection 
result of the level which indicates high memory performance is given from 
the memory-function detection module 61, the speech-lexicon-index 
selection module 706 decides to use the speech-lexicon index 705-i which 
indicates the speech data that realizes a high-quality speech-synthesis 
processing, because of the sufficient memory. Whereas when the detection 
result of the level which indicates low memory performance is given, the 
module 706 decides to use the speech-lexicon index 705-i which indicates 
the speech data that realizes a low-quality speech-synthesis processing, 
because of the small memory. 
In other words, on the assumption that there are speech data "SA" and "A" 
in the speech lexicon 2, when there is not sufficient memory, the 
speech-lexicon-index selection module 706 selects the speech-lexicon index 
705-i which has indicates only the speech data "A", because the speech 
data "A" may be also usable for the speech data "SA". When there is 
sufficient memory, the module 706 selects the speech-lexicon index 705-i 
which indicates both speech data "A" and "SA". 
And subsequently, the speech-lexicon-download control module 707 receives 
the decision result of the speech-lexicon-index selection module 706, and 
reads out the speech data from the speech lexicon 2 which is indicated by 
the selected speech-lexicon index 705-i, the speech data read out being 
stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 12, by means of changing the quality of the 
speech data stored in the speech-data buffer 90 based on the memory 
performance, the speech-synthesis processing suitable for the memory 
performance may be realized by adjusting the amount of the speech data 
directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 13, this system includes the 
single speech lexicon 2, and the adjustment module 7 consisting of a 
speech-data-frequency table 708, a frequency-threshold decision module 
709, and the speech-lexicon-download control module 707. 
In the embodiment of FIG. 13 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the frequency-threshold decision module 709 decides a frequency of use of 
the speech data based on the level detected in the memory-function 
detection module 61. For example, when the detection result of the level 
which indicates the high memory performance is given from the 
memory-function detection module 61, the frequency-threshold decision 
module 709 selects a small threshold level of the frequency of use to 
allow a storage of a large amount of the speech data, because of the 
sufficient memory. Whereas when the detection result of the level which 
indicates the low memory performance is given, the module 709 selects a 
large threshold level of the frequency of use to limit the storage to a 
small amount of the speech data, because of the small memory. 
And subsequently, the speech-lexicon-download control module 707 receives 
the decision result of the frequency-threshold decision module 709, and 
reads out the speech data from the speech lexicon 2, which indicates a 
larger frequency of use than a selected frequency-threshold level, based 
on management data of the speech-data-frequency table 708 managing the 
frequency information of the speech data. The speech data read out is 
stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 13, by means of changing the amount of the 
speech data stored in the speech-data buffer 90 based on the memory 
performance, the speech-synthesis processing suitable for the memory 
performance may be realized by adjusting the amount of the speech data 
directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 14, this system includes the 
plurality of speech lexicons 2-i (i=1 to n) which manage respective speech 
data having different tones such as a man's voice, a woman's voice, a 
child voice, and an old person's voice, and the adjustment module 7 
consists of a tone decision module 710, and the speech-lexicon selection 
module 701. 
In the embodiment of FIG. 14 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the tone decision module 710 selects the tone of the speech data based on 
the level detected in the memory-function detection module 61. For 
example, when the detection result of the level which indicates the high 
memory performance is given from the memory-function detection module 61, 
the tone decision module 710 selects a plurality of tones to allow a 
storage of the speech data of many tones, because of the sufficient 
memory. Whereas when the detection result of the level which indicates the 
low memory performance is given, the module 710 selects, for example, a 
specific tone to limit the storage of the speech data to one tone, because 
of the small memory. 
And subsequently, the speech-lexicon selection module 701 receives the 
decision result of the tone decision module 710, and reads out the speech 
data of the selected tones from the speech lexicon 2, the speech data read 
out being stored in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 14, by means of changing the number of 
tones of the speech data stored in the speech-data buffer 90 based on the 
memory performance, the speech-synthesis processing suitable for the 
memory performance may be realized by adjusting the amount of the speech 
data directed to the acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 15, this system includes a 
single word lexicon 1, and the adjustment module 7 consists of a plurality 
of word-lexicon indexes 711-i (i=1 to m), a word-lexicon-index selection 
module 712, and a word-lexicon-download control module 713. 
In the embodiment of FIG. 15 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the word-lexicon-index selection module 712 selects the word-lexicon index 
711-i to be utilized based on the level detected in the memory-function 
detection module 61. For example, when the detection result of the level 
which indicates high memory performance is given from the memory-function 
detection module 61, the word-lexicon-index selection module 712 decides 
to use the word-lexicon index 711-i which indicates the word information 
that realizes the high-quality speech-synthesis processing, because of the 
sufficient memory. Whereas when the detection result of the level which 
indicates low memory performance is given, the module 712 decides to use 
the word-lexicon index 711-i which indicates the word information that 
realizes the low-quality speech-synthesis processing, because of the small 
memory. 
And subsequently, the word-lexicon-download control module 713 receives the 
decision result of the word-lexicon-index selection module 712, and reads 
out the word information from the word lexicon 1, which is indicated by 
the selected word-lexicon index 711-i, the word information read out being 
stored in the word information buffer 80. 
Thus, in the embodiment of FIG. 15, by means of changing the quality of the 
word information stored in the word-information buffer 80 based on the 
memory performance, the speech-synthesis processing suitable for the 
memory performance may be realized by adjusting the amount of the word 
information directed to the language processing module 3. 
On the other hand, in the embodiment of FIG. 16, this system includes the 
single word lexicon 1, and the adjustment module 7 consisting of a 
word-frequency table 714, a word-frequency-threshold decision module 715, 
and the word-lexicon-download control module 713. 
In the embodiment of FIG. 16 constructed in such a structure, once the 
memory-function detection module 61 detects the memory capacity or the 
memory-using situation, and produces the level of the detection result, 
the word-frequency-threshold decision module 715 selects the threshold 
level of the frequency of use of the word information based on the level 
detected in the memory-function detection module 61. For example, when the 
detection result of the level which indicates the high memory performance 
is given from the memory-function detection module 61, the 
word-frequency-threshold decision module 715 selects a small threshold 
level of the frequency of use to allow storage of a large amount of word 
information, because of the sufficient memory. Whereas when the detection 
result of the level which indicates low memory performance is given, the 
module 715 selects a large threshold level of the frequency of use to 
limit the storage to a small amount of word information, because of the 
small memory. 
And subsequently, the word-lexicon-download control module 713 receives the 
decision result of the word-frequency-threshold decision module 715, and 
reads out the word information from the word lexicon 1, which indicates a 
larger frequency of use than a selected frequency threshold level, based 
on management data of the word-frequency table 714 managing the frequency 
information of the word information. The word information read out is 
stored in the word information buffer 80. 
Thus, in the embodiment of FIG. 16, by means of changing the amount of the 
word information stored in the word-information buffer 80 based on the 
memory performance, the speech-synthesis processing suitable for the 
memory performance may be realized by adjusting the amount of the word 
information directed to the language processing module 3. 
As described above, in the embodiments of FIGS. 8 to 16, the 
speech-synthesis processing suitable for the memory performance may be 
realized by adjusting the amount of the speech data directed to the 
acoustic processing module 4 or the amount of the word information 
directed to the language processing module 3, according to the detection 
result of the memory-function detection module 61. 
Next, descriptions will be given of still other embodiments of the speech 
synthesis system according to the present invention, by referring to FIGS. 
17 to 20. FIGS. 17 to 20 show examples of configurations of the speech 
synthesis system in the case that a second-order-storage-device-function 
detection module 62 is used in the detection module 6. This function 
detection module 62 detects an access performance of the second-order 
storage device by, for example, performing a read processing. This 
detection result is processed to be represented with any of the given 
levels. 
In the embodiment of FIG. 17, this system also includes the single speech 
lexicon 2, and the adjustment module 7 consisting of the plurality of 
speech-lexicon indexes 705-i (i=1 to m), the speech-lexicon-index 
selection module 706, and the speech-lexicon-download control module 707. 
In the embodiment of FIG. 17 constructed in such a structure, once the 
function detection module 62 detects the access performance of the 
second-order storage device which stores the speech lexicon 2 by means of 
reading the speech data of the speech lexicon 2, and produces the level of 
the detection result, the speech-lexicon-index selection module 706 
selects the speech-lexicon index 705-i to be utilized based on the level 
detected in the function detection module 62. For example, when the 
detection result of the level which indicates high-speed access 
performance is given from the function detection module 62, the 
speech-lexicon-index selection module 706 decides to use the 
speech-lexicon index 705-i which indicates the speech data that realizes a 
low-quality speech-synthesis processing, because the speech-synthesis 
processing may be performed by accessing the speech lexicon 2 on each 
occasion. Whereas when the detection result of the level which indicates 
slow-speed access performance is given, the module 706 decides to use the 
speech-lexicon index 705-i which indicates the speech data that realizes a 
high-quality speech-synthesis processing, because the speech-synthesis 
processing may not be performed by accessing the speech lexicon 2 on each 
occasion. 
In other words, on the assumption that there are the speech data "SA" and 
"A" in the speech lexicon 2, when good access performance is obtained in 
the second-order storage device which stores the speech lexicon 2, the 
speech-lexicon-index selection module 706 decides to use the 
speech-lexicon index 705-i which indicates only the speech data "A", 
because the speech data "A" may be also usable for the speech data "SA". 
When the good access performance is not obtained, the module 706 decides 
to use the speech-lexicon index 705-i which indicates both speech data "A" 
and "SA". 
And subsequently, the speech-lexicon-download control module 707 receives 
the decision result of the speech-lexicon-index selection module 706, and 
reads out the speech data indicated by the selected speech-lexicon index 
705-i, from the speech lexicon 2. The speech data read out is stored in 
the speech-data buffer 90. In this configuration, when the speech data for 
realizing the high-quality speech-synthesis processing is not read out to 
the speech-data buffer 90, the acoustic processing module 4 processes to 
directly access the speech data in the speech lexicon 2 of the 
second-order storage device having the high-speed access performance. 
Thus, in the embodiment of FIG. 17, by means of changing the quality of the 
speech data stored in the speech-data buffer 90 based on the access 
performance of the second-order storage device, the speech-synthesis 
processing suitable for the access performance of that storage device may 
be realized by adjusting the amount of the speech data directed to the 
acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 18, this system includes the 
single speech lexicon 2, and the adjustment module 7 consisting of the 
speech-data-frequency table 708, the frequency-threshold decision module 
709, and the speech-lexicon-download control module 707. 
In the embodiment of FIG. 18 constructed in such a structure, as described 
above, once the second-order-storage-device-function detection module 62 
detects the access performance of the second-order storage device which 
stores the speech lexicon 2, and produces the level of the detection 
result, the frequency-threshold decision module 709 selects the threshold 
level of the frequency of use of the speech data based on the level 
detected in the function detection module 62. For example, when the 
detection result of the level which indicates the high-speed access 
performance of the storage device is given from the function detection 
module 62, the frequency-threshold decision module 709 selects a large 
threshold level of the frequency of use to limit the storage to the small 
amount of the speech data, because the speech-synthesis processing may be 
performed by accessing the speech lexicon 2 on each occasion. Whereas when 
the detection result of the level which indicates the slow-speed access 
performance is given, the module 709 selects a small threshold level of 
the frequency of use to allow the storage of the large amount of the 
speech data, because the speech-synthesis processing may not be performed 
by accessing the speech lexicon 2 on each occasion. 
And subsequently, the speech-lexicon-download control module 707 receives 
the decision result of the frequency-threshold decision module 709, and 
reads out the speech data from the speech lexicon 2, which indicates the 
larger frequency of use than the selected frequency threshold level, based 
on management data of the speech-data-frequency table 708 managing the 
frequency information of the speech data. The speech data read out is 
stored in the speech data buffer 90. 
Thus, in the embodiment of FIG. 18, by means of changing the amount of the 
speech data stored in the speech-data buffer 90 based on the access 
performance of the second-order storage device, the speech-synthesis 
processing suitable for the access performance of the storage device may 
be realized by adjusting the amount of the speech data directed to the 
acoustic processing module 4. 
On the other hand, in the embodiment of FIG. 19, this system includes the 
single word lexicon 1, and the adjustment module 7 consisting of the 
plurality of word-lexicon indexes 711-i (i=1 to m), the word-lexicon-index 
selection module 712, and the word-lexicon-download control module 713. 
In the embodiment of FIG. 19 constructed in such a structure, once the 
second-order-storage-device function detection module 62 detects the 
access performance of the second-order storage device which stores the 
word lexicon 1 by means of reading the word information of the word 
lexicon 1, and produces the level of the detection result, the 
word-lexicon-index selection module 712 selects the word-lexicon index 
711-i to be utilized based on the level detected in the function detection 
module 62. For example, when the detection result of the level which 
indicates the high-speed access performance is given from the function 
detection module 62, the word-lexicon-index selection module 712 decides 
to use the word-lexicon index 711-i which indicates the word information 
that realizes the low-quality word-synthesis processing, because the 
speech-synthesis processing may be performed by accessing the word lexicon 
1 on each occasion. Whereas when the detection result of the level which 
indicates the slow-speed access performance is given, the module 712 
decides to use the word-lexicon index 711-i which indicates the word 
information that realizes the high-quality speech-synthesis processing, 
because the speech-synthesis processing may not be performed by accessing 
the word lexicon 1 on each occasion. 
In other words, when the good access performance is obtained in the 
second-order storage device which stores the word lexicon 1, the 
word-lexicon-index selection module 712 decides to use the word-lexicon 
index 711-i which indicates main word information. When the good access 
performance is not obtained, the module 712 decides to use the 
speech-lexicon index 711-i which indicates both the main word information 
and its additional word information. 
And subsequently, the word-lexicon-download control module 713 receives the 
decision result of the word-lexicon-index selection module 712, and reads 
out the word information, which is indicated by the selected word-lexicon 
index 711-i, from the word lexicon 1. The word information read out is 
stored in the word-information buffer 80. In this configuration, when the 
word information for realizing the high-quality speech-synthesis 
processing is not read out to the word-information buffer 80, the language 
processing module 3 processes to directly access the word information from 
the word lexicon 1 of the second-order storage device having the 
high-speed access performance. 
On the other hand, in the embodiment of FIG. 20, this system includes the 
single word lexicon 1, and the adjustment module 7 consists of the 
word-frequency table 714, the word-frequency-threshold decision module 
715, and the word-lexicon-download control module 713. 
In the embodiment of FIG. 20 constructed in such a structure, as described 
above, once the second-order-storage-device-function detection module 62 
detects the access performance of the second-order storage device which 
stores the word lexicon 1, and produces the level of the detection result, 
the word-frequency-threshold decision module 715 selects the threshold 
level of the frequency of use of the word information based on the level 
detected in the function detection module 62. For example, when the 
detection result of the level which indicates the high-speed access 
performance of the storage device is given from the function detection 
module 62, the word-frequency-threshold decision module 715 selects the 
large threshold level of the frequency of use to limit the storage to the 
small amount of word information, because the speech-synthesis processing 
may be performed by accessing the word lexicon 1 on each occasion. Whereas 
when the detection result of the level which indicates the slow-speed 
access performance is given, the module 715 selects a small threshold 
level of the frequency of use to allow the storage of the large amount of 
word information, because the speech-synthesis processing may not be 
performed by accessing the word lexicon 1 on each occasion. 
And subsequently, the word-lexicon-download control module 713 receives the 
selection result of the word-frequency-threshold decision module 715, and 
reads out the word information from the word lexicon 1, which indicates 
the larger frequency of use than the selected frequency threshold level, 
based on management data of the word-information-frequency table 714 
managing the frequency information of the word information. The word 
information read out is stored in the word-information buffer 80. 
Thus, in the embodiment of FIG. 20, by means of changing the amount of the 
word information stored in the word-information buffer 80 based on the 
access performance of the second-order storage device, the 
speech-synthesis processing suitable for the access performance of the 
storage device may be realized by adjusting the amount of the word 
information directed to the language processing module 3. 
As described above, in the embodiments of FIGS. 17 to 20, the 
speech-synthesis processing suitable for the access performance of the 
second-order storage device may be realized by adjusting the amount of the 
speech data directed to the acoustic processing module 4 or the amount of 
the word information directed to the language processing module 3, 
according to the detection result of the 
second-order-storage-device-function detection module 62. 
Next, descriptions will be given of other embodiments of the speech 
synthesis system according to the present invention, by referring to FIGS. 
21 and 22. FIGS. 21 and 22 show examples of configurations of the speech 
synthesis system in the case that a D/A-converter-sampling-frequency 
detection module 63 is used in the detection module 6. This frequency 
detection module 63 detects a sampling frequency of the D/A converter 5 
by, for example, querying the operating system. 
In the embodiment of FIG. 21, the system includes the plurality of speech 
lexicons 2-i (i=1 to n) which manage the speech data having different 
sampling frequencies. And the adjustment module 7 consists of the 
speech-lexicon selection module 701. 
In the embodiment of FIG. 21 constructed in such a structure, once the 
D/A-converter-sampling-frequency detection module 63 detects the sampling 
frequency of the D/A converter 5, the speech-lexicon selection module 701 
reads out, according to the detection result, the associated speech data 
from the speech lexicon 2-i which manages the speech data having the same 
sampling frequency. And the speech data read out is stored in the 
speech-data buffer 90. 
Thus, in the embodiment of FIG. 21, by means of changing the sampling 
frequency of the speech data stored in the speech-data buffer 90 to a 
frequency adjustable for the D/A converter 5, the speech-synthesis 
processing suitable for the D/A converter 5 may be realized. 
On the other hand, in the embodiment of FIG. 22, the system includes the 
single speech lexicon 2 which manages the speech data having the high 
sampling frequency of, for example, 48 kHz. The adjustment module 7 
consists of the down-sampling processing module 702. 
In the embodiment of FIG. 5, once the frequency detection module 63 detects 
the sampling frequency of the D/A converter 5, the down-sampling 
processing module 702 receives the detection result of the sampling 
frequency, and derives the speech data from the speech lexicon 2 to store 
it in the speech-data buffer 90 in the suitable sampling frequency. For 
example, when the sampling frequency of the D/A converter 5 is 48 kHz, the 
down-sampling processing module 702 reads out directly the speech data 
stored in the speech lexicon 2, and stores it in the speech-data buffer 
90. When the sampling frequency of the D/A converter 5 is 16 kHz, the 
down-sampling processing module 702 reads out the speech data stored in 
the speech lexicon 2 with down-sampling to 16 kHz, and stores it in the 
speech-data buffer 90. 
Thus, in the embodiment of FIG. 22, by means of changing the sampling 
frequency of the speech data stored in the speech-data buffer 90 to the 
frequency adjustable for the D/A converter 5, the speech-synthesis 
processing suitable for the D/A converter 5 may be realized. 
As described above, in the embodiments of FIGS. 21 and 22, the 
speech-synthesis processing suitable for the D/A converter 5 may be 
realized by adjusting the sampling frequency of the speech data directed 
to the acoustic processing module 4, according to the detection result of 
the frequency detection module 63. 
Next, descriptions will be given of still other embodiments of the speech 
synthesis system according to the present invention, by referring to FIGS. 
23 and 24. FIGS. 23 and 24 show examples of configurations of the speech 
synthesis system in the case that a D/A-converter-quantization-bit 
detection module 64 is used in the detection module 6. This bit detection 
module 64 detects the number of the quantization bits of the D/A converter 
5 by for example querying to the operating system. 
In the embodiment of FIG. 23, the system includes the plurality of speech 
lexicons 2-i (i=1 to n) which manage the speech data having the different 
numbers of the quantization bits. And the adjustment module 7 consists of 
the speech-lexicon selection module 701. 
In the embodiment of FIG. 23 constructed in such a structure, once the bit 
detection module 64 detects the number of the quantization bits of the D/A 
converter 5, the speech-lexicon selection module 701 reads out, according 
to the detection result, the associated speech data from the speech 
lexicon 2-i which manages the speech data having the detected number of 
the quantization bits. And the speech data read out is stored in the 
speech-data buffer 90. 
Thus, in the embodiment of FIG. 23, by means of changing the number of the 
quantization bits of the speech data stored in the speech-data buffer 90 
to a number adjustable for the D/A converter 5, the speech-synthesis 
processing suitable for the D/A converter 5 may be realized. 
On the other hand, in the embodiment of FIG. 24, the system includes the 
single speech lexicon 2 which manages the speech data having the large 
number of quantization bits, for example 16, bits. The adjustment module 7 
consists of the quantization-bit changing module 704. 
In the embodiment of FIG. 24, once the bit detection module 64 detects the 
number of the quantization bits of the D/A converter 5, the 
quantization-bit changing module 704 receives the detection result, and 
derives the speech data from the speech lexicon 2 to store it in the 
speech-data buffer 90 in the suitable number of the quantization bits. For 
example, when the number of the quantization bits of the D/A converter 5 
is 16 bits, the quantization-bit changing module 704 reads out directly 
the speech data stored in the speech lexicon 2, and stores it in the 
speech-data buffer 90. When the number of the quantization bits of the D/A 
converter 5 is 8 bits, the quantization-bit changing module 704 reads out 
the speech data stored in the speech lexicon 2, changes it to 8-bit 
quantization, and stores it in the speech-data buffer 90. 
Thus, in the embodiment of FIG. 24, by means of changing the number of the 
quantization bits of the speech data stored in the speech-data buffer 90 
to the number adjustable for the D/A converter 5, the speech-synthesis 
processing suitable for the D/A converter 5 may be realized. 
As described above, in the embodiments of FIGS. 23 and 24, the 
speech-synthesis processing suitable for the D/A converter 5 may be 
realized by adjusting the number of the quantization bits of the speech 
data directed to the acoustic processing module 4, according to the 
detection result of the bit detection module 64. 
In the embodiments of FIGS. 4 to 24, the detection module 6 includes one of 
the CPU-function detection module 60, the memory-function detection module 
61, the second-order-storage-device-function detection module 62, the 
D/A-converter-sampling-frequency detection module 63, and the 
D/A-converter-quantization-bit detection module 64. And based on the 
detection result, this system changes the sampling frequency or the number 
of the quantization bits of the speech data stored in the speech-data 
buffer 90, or changes the amount of the word information stored in the 
word-information buffer 80. 
Furthermore, this speech synthesis system may be also constructed with a 
plurality of the detection modules, or with a combination of the changes 
of the sampling frequency and the number of the quantization bits of the 
speech data. 
Next, descriptions will be given of other embodiments of the speech 
synthesis system having such configurations, by referring to FIGS. 25 to 
28. FIGS. 25 to 28 show examples of configurations of the speech synthesis 
system in the case of having the plurality of the detection modules. 
In the embodiment of FIG. 25, the detection module 6 comprises the 
memory-function detection module 61, and the 
second-order-storage-device-function detection module 62. And the 
adjustment module 7 comprises the speech-lexicon-download control module 
707, the speech-data-frequency table 708, and the frequency-threshold 
decision module 709. 
In the embodiment of FIG. 25 constructed in such a structure, the 
frequency-threshold decision module 709 selects the threshold level of the 
frequency of use of the speech data based on the detection results of the 
memory-function detection module 61 and the device-function detection 
module 62. For example, when the good access performance is obtained in 
the second-order storage device, there is no need of reading out a large 
amount of the speech data to the speech-data buffer 90, however, at that 
time if there is the sufficient memory capacity, the threshold of the 
frequency of use is selected to be the small value to read out the large 
amount of the speech data. As described above, with taking into account 
the detection results of the two detection modules, the threshold of the 
frequency of use of the speech data is selected. 
And subsequently, the speech-lexicon-download control module 707 receives 
the selection result of the frequency-threshold decision module 709, and 
reads out the speech data which indicates the larger frequency of use than 
the selected frequency threshold, from the speech lexicon 2, based on the 
management data of the speech-data-frequency table 708. The speech data 
read out is stored in the speech-data buffer 90. 
In the embodiment of FIG. 26, the detection module 6 comprises the 
memory-function detection module 61, and the 
second-order-storage-device-function detection module 62. And the 
adjustment module 7 comprises the word-lexicon-download control module 
713, the word-frequency table 714, and the word-frequency-threshold 
decision module 715. 
In the embodiment of FIG. 26 constructed in such a structure, the 
word-frequency-threshold decision module 715 selects the threshold level 
of the frequency of use of the word information based on the detection 
results of the memory-function detection module 61 and the device-function 
detection module 62. For example, when the good access performance is not 
obtained in the second-order storage device, and there is the sufficient 
memory capacity, the threshold of the frequency of use is selected to be 
an extremely small value to allow the reading out of the speech data to be 
as large as possible. As described above, by taking into account the 
detection results of the two detection modules, the threshold of the 
frequency of use of the word information is selected. 
And subsequently, the word-lexicon-download control module 713 receives the 
selection result of the word-frequency-threshold decision module 715, and 
reads out the word information which indicates the larger frequency of use 
than the selected frequency threshold, from the word lexicon 1, based on 
the management data of the word-frequency table 714. The word information 
read out is stored in the word-information buffer 80. 
In the embodiment of FIG. 27, the detection module 6 comprises the 
CPU-function detection module 60, and the memory-function detection module 
61. And the adjustment module 7 comprises the sampling-frequency decision 
module 700, the down-sampling processing module 702, the 
speech-lexicon-download control module 707, the speech-data-frequency 
table 708, and the frequency-threshold decision module 709. 
In the embodiment of FIG. 27 constructed in such a structure, the 
frequency-threshold decision module 709 selects the threshold level of the 
frequency of use of the speech data based on the detection result of the 
memory-function detection module 61. And in response to the decision 
result, the speech-lexicon-download control module 707 reads out the 
speech data which indicates the larger frequency of use than the decided 
frequency threshold, from the speech lexicon 2, based on the management 
data of the speech-data-frequency table 708. 
Further, the sampling-frequency decision module 700 selects the sampling 
frequency of the speech data based on the detection result of the 
CPU-function detection module 60 and the memory-function detection module 
61. And in response to the selection result, the down-sampling processing 
module 702 down-samples the speech data which is read out by the 
speech-lexicon-download control module 707 to the selected sampling 
frequency. The down-sampled speech data is stored in the speech-data 
buffer 90. 
In the embodiment of FIG. 28, the detection module 6 comprises the 
CPU-function detection module 60, and the memory-function detection module 
61. And the adjustment module 7 comprises the sampling-frequency decision 
module 700, the down-sampling processing module 702, the quantization-bit 
decision module 703, and the quantization-bit changing module 704. 
In the embodiment of FIG. 28 constructed in such a structure, the 
sampling-frequency decision module 700 selects the sampling frequency of 
the speech data based on the detection results of the CPU-function 
detection module 60 and the memory-function detection module 61. And in 
response to the selection result, the down-sampling processing module 702 
down-samples the speech data which is read out by the speech lexicon 2 to 
the selected sampling frequency. 
Further, the quantization-bit decision module 703 decides the number of the 
quantization bits of the speech data based on the detection results of the 
CPU-function detection module 60 and the memory-function detection module 
61. And in response to the selection result, the quantization-bit changing 
module 704 changes the number of the quantization bits of the speech data 
which is read out by the down-sampling processing module 702 to the 
selected number of the quantization bits. The speech data for which the 
number of the quantization bits has been changed is stored in the 
speech-data buffer 90. 
In this way, in the present invention, the detection module 6 includes the 
combinations of the CPU-function detection module 60, the memory-function 
detection module 61, and the second-order-storage-device-function 
detection module 62. Therefore, based on the detection results of these 
detection modules, in this system, the speech data to be stored in the 
speech-data buffer 90 is adjustable, and the word information to be stored 
in the word-information buffer 80 is adjustable. 
At this time, when the sampling frequency of the speech data stored in the 
speech-data buffer 90 is not identical to the sampling frequency of the 
D/A converter 5, the sampling frequency of the synthesized speech signal 
generated in the acoustic processing module 4 also will not identical to 
the sampling frequency of the D/A converter 5. And when the number of the 
quantization bits of the speech data stored in the buffer 90 is not 
identical to the number of the quantization bits of the D/A converter 5, 
the number of the quantization bits of the synthesized signal generated in 
the acoustic processing module 4 also will not identical to the number of 
the quantization bits of the D/A converter 5. 
As previously described in FIG. 2, once the bit adjustment module 7a 
detects mismatch in the number of the quantization bits based on the 
detection result of the bit detection module 64, the number of the 
quantization bits of the synthesized speech signal generated in the 
acoustic processing module 4 is adjusted to equal that of the D/A 
converter 5 by shifting bit data of the synthesized speech signal. 
And in the embodiment in FIG. 2, once the frequency adjustment module 7b 
detects mismatch in the sampling frequency based on the detection result 
of the frequency detection module 63, the sampling frequency of the 
synthesized speech signal generated in the acoustic processing module 4 is 
adjusted to equal that of the D/A converter 5 by sampling the bit data of 
the synthesized speech signal. 
The speech synthesis system according to the present invention is 
characterized in that inner parameters necessary for the speech-synthesis 
processing are adjustable to be adapted to the hardware performance of the 
computer in which the software of the system is run. In the embodiments 
described above, to realize such features, the configurations with the 
detection module 6 have been represented. However, the present invention 
is not limited to such configurations, the system may be realized with 
another configuration with the setting module according to the present 
invention, by which the user can set performance or conditions of the 
hardware part of a computer with the dialogic processing between the user 
and the computer. 
In the speech synthesis system, for producing the audible analog signal, 
the D/A converter is required in the computer. However, the user's 
computer is not always equipped with the D/A converter. In this case, in 
the speech synthesis system according to the present invention, if the 
detection module 6 detects that the D/A converter is not installed in the 
computer or is not available as shown in FIG. 29, data of the synthesized 
speech signal generated in the acoustic processing module 4 is adjusted by 
the adjustment modules 7a and 7b, and is stored as a data file in a 
storage device such as a hard disk 50. When there are not the adjustment 
modules 7a and 7b in the system, the synthesized speech signal generated 
in the acoustic processing module 4 directly passes to the storage device. 
And if the data file is transmitted to another computer in which the D/A 
converter is installed for the speech synthesis system, and is passed to 
the D/A converter in an appropriate manner, the audible analog signal of 
synthesized speech signal may be produced. 
Next, descriptions will be given of procedures of the speech synthesizing 
methods, by referring to FIGS. 30 to 32. FIG. 30 shows a basic procedure 
of the speech synthesizing method according to the present invention. 
First, in a step S10, the performance or conditions of the hardware part of 
the computer in which the speech synthesis system is constructed, is 
detected. 
Second, in a step S11, based on the detection result of the performance or 
the conditions in the step S10, word information which is derived from a 
word lexicon is adjusted, and is given to the language processing module. 
And speech data which is derived from a speech lexicon is also adjusted, 
and is given to the acoustic processing module. 
Third, in a step S12, language processing for speech synthesis of the input 
text is performed by using adjusted word information in the step S11. 
Finally, in a step S13, the synthesized speech signal of the input text is 
generated by using adjusted speech data, in response to the result of the 
language processing in the step S12. 
The synthesized speech data generated in the step S13, when this speech 
synthesizing method is installed in the computer equipped with the D/A 
converter, may be converted to the audible analog signal by the D/A 
converter. 
FIG. 31 shows another basic procedure of the speech synthesizing method 
according to the present invention. 
First, in a step S20, performance or conditions of the hardware part of the 
computer in which the speech synthesis system is constructed, is set by 
the user with the dialogic processing between the user and the computer. 
Second, in a step S21, based on the setting result of the performance or 
the conditions in the step S20, word information which is derived from a 
word lexicon is adjusted, and is given to the language processing module. 
And speech data which is derived from a speech lexicon is also adjusted, 
and is given to the acoustic processing module. 
Third, in a step S22, language processing for speech synthesis of the input 
text is performed by using adjusted word information in the step S21. 
Finally, in a step S23, the synthesized speech signal of the input text is 
generated by using adjusted speech data, in response to the result of the 
language processing in the step S22. 
The synthesized speech data generated in the step S23, when this speech 
synthesizing method is installed in the computer equipped with the D/A 
converter, may be converted to the audible analog signal by the D/A 
converter. 
FIG. 32 shows an example of the procedure embodiment of the speech 
synthesizing method according to the present invention. 
First, in a step S30, the CPU performance is detected from the CPU 
information which the operating system has, or the CPU performance is 
discriminated by running a bench-mark program. 
Second, in a step S31, the sampling frequency is selected based on the CPU 
performance detected in the step S30. 
Third, in a step S32, the speech lexicon associated with the selected 
sampling frequency in the step S31 is selected. 
Forth, in a step S33, the speech data in the selected speech lexicon in the 
step S32 is downloaded to the memory. 
Fifth, in a step S34, language processing for speech synthesis of the input 
text is performed by using the word information. 
Finally, in a step S35, the synthesized speech signal of the input text is 
generated by using a downloaded speech data in the memory, in response to 
the result of the language processing in the step S34. 
The synthesized speech data generated in the step S35, when this speech 
synthesizing method is installed in the computer equipped with the D/A 
converter, may be converted to the audible analog signal by the D/A 
converter. 
FIG. 33 shows another example of the procedure embodiment of the speech 
synthesizing method according to the present invention. 
First, in a step S40, the memory capacity is detected from the memory 
information which the operating system has. 
Second, in a step S41, the word-lexicon index associated with the detected 
memory capacity is selected based on the memory capacity detected in the 
step S40. 
Third, in a step S42, the word information which is indicated by the 
selected word-lexicon index in the step S41 is downloaded to the memory. 
Fourth, in a step S43, language processing for speech synthesis of the 
input text is performed by using the word information downloaded in the 
step S42. 
Finally, in a step S44, the synthesized speech signal of the input text is 
generated by using the speech data, in response to the result of the 
language processing in the step S43. 
The synthesized speech data generated in the step S44, when this speech 
synthesizing method is installed in the computer equipped with the D/A 
converter, may be converted to the audible analog signal by the D/A 
converter. 
As has already been stated, the speech synthesis system may be constructed 
with the software except the D/A converter. Therefore, the modules 
constructing the speech synthesis system according to the present 
invention indicates the modules of the software. And each step of the 
speech synthesizing method may be performed by running the software. The 
spirit and scope of this invention exists not only in the hardware in 
which the software is installed, but also in any storage device in which 
the software may be stored. Thus, the storage device such as a floppy 
disk, or the CD-ROM, in which the software for the speech synthesis system 
is stored, is also covered by the present invention. 
According to the speech synthesis system, according to the hardware 
performance or conditions detected in the detection module, the word 
information directed to the language processing module is adjusted, and 
the number of the quantization bits, the sampling frequency, and the 
amount of supply of the speech data directed to the acoustic processing 
module are adjusted. 
By such adjustment, with the computer having high hardware performance, the 
language processing module and the acoustic processing module may perform 
superior speech-synthesis processing, and with the computer having poor 
hardware performance, these modules may perform optimum speech-synthesis 
processing in the range of that hardware performance. 
In this way, according to the speech synthesis system, the speech-synthesis 
processing suitable for any computer in which its software is run, may be 
realized. Thus, the user may construct good speech synthesis system with 
the computer which has been used by the user. 
Further, the present invention is not limited to these embodiments, but 
various variations and modifications may be made without departing from 
the scope of the present invention.