JP2004246313A - Telephone set, telephone calling method, and voice frequency converting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a telephone set which reduces mishearing of a voice including a hard-to-hear voice frequency component. <P>SOLUTION: The telephone set has a frequency converter 6 which expands voice data received from outside into voice frequency components, generates frequency-converted data as voice data by multiplying the respective voice frequency components by a specified value, and sending the voice data to a voice output means 8. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a telephone for transmitting and receiving voice data, a telephone call method, and a voice frequency conversion method.
[0002]
[Prior art]
A conventional telephone will be described.
[0003]
FIG. 11 is a block diagram showing a configuration example of a conventional telephone, showing a transmitting unit 210a of one telephone and a receiving unit 220b of the other telephone.
[0004]
A conventional telephone has a configuration including a transmission unit 210 and a reception unit 220. As shown in FIG. 11, the transmission unit 210a includes a microphone 1 for inputting audio, an A / D converter 2 for converting an analog signal into a digital signal, and an encoder 3 for encoding a digital signal. ing. The receiving unit 220b includes a decoder 5 for decoding encoded data, a D / A converter 7 for converting a digital signal into an analog signal, and a speaker 8 serving as audio output means for outputting audio. I have. The encoder 3 provided in the transmission unit 210a of one telephone and the decoder 5 provided in the reception unit 220b of the other telephone are communicably connected via the transmission path 4.
[0005]
Note that the receiving unit 220a of one telephone has the same configuration as the receiving unit 220b, and the transmitting unit 210b of the other telephone has the same configuration as the transmitting unit 210a. ing.
[0006]
The operation of the telephone having the above configuration will be described.
[0007]
In FIG. 11, when the voice of the caller is input to the microphone 1 of the transmission unit 210a, the microphone 1 converts the voice into an electric signal, and converts the voice signal, which is the voice data of the analog signal, to the A / D converter 2. Send out. Upon receiving the audio signal from the microphone 1, the A / D converter 2 samples the audio signal at a predetermined time, converts the audio signal into audio digital data, which is audio data of a digital signal, and sends it to the encoder 3. Upon receiving the audio digital data from the A / D converter 2, the encoder 3 encodes the audio digital data, and transmits the encoded data to the decoder 5 via the transmission path 4.
[0008]
When receiving the encoded data from the encoder 3, the decoder 5 decodes the encoded data and sends out the audio digital data to the D / A converter 7. Upon receiving the audio digital data from the decoder 5, the D / A converter 7 converts the audio digital data of the digital signal into an analog audio signal and sends the audio signal to the speaker 8. When receiving the audio signal from the D / A converter 7, the speaker 8 converts the audio signal to electroacoustic and outputs the audio signal as a voice (for example, see Patent Document 1).
[0009]
As another configuration of a telephone, a telephone provided with a means for making it easy to hear a voice is disclosed (for example, see Patent Document 2).
[0010]
[Patent Document 1]
JP 2001-285409 A
[Patent Document 2]
JP 2002-244686 A
[0011]
[Problems to be solved by the invention]
The conventional telephone described above has the following problems.
[0012]
Elders are generally more difficult to hear at higher audio frequencies. In particular, the tendency is stronger in telephone calls. Therefore, for example, a person's last name “Kato” may be mistaken for “Sato”. This is considered to be due to the fact that among the voice frequency components of the vowels “A” and “A” of “K” and “A”, there is a maximum portion of the amplitude near 2.5 KHz on the high frequency side. Then, when such mistakes in the number of hearings increase, there is a problem that communication between the callers is not smoothly performed.
[0013]
In recent years, in response to this problem, Japanese Patent Application Laid-Open No. 2002-244686 describes a "voice processing method, a telephone and a relay station using the same", in which the higher the treble, the greater the amount of frequency conversion to the lower frequency range. Technology proposals have been made. According to this publication, a frequency is detected from a signal received from a transmission line, and an audio signal frequency-shifted by a frequency conversion unit is reproduced by an audio circuit unit. This configuration is an effective means for an encoding system in which frequency characteristics can be easily detected at the time of reception, but is a codec (codec) such as μ-law or adaptive differential pulse code modulation (ADPCM) used in general public networks. / Decode).
[0014]
The present invention has been made in order to solve the problems of the conventional technology as described above, and a telephone, a telephone call method, and a voice frequency conversion method for reducing erroneous listening of voice including voice frequency components which are difficult to hear. The purpose is to provide.
[0015]
[Means for Solving the Problems]
The telephone of the present invention for achieving the above object develops audio data received from the outside into audio frequency components, and creates frequency conversion data which is audio data obtained by multiplying each audio frequency component by a predetermined magnification. This is a configuration having a frequency converter that sends out to audio output means for outputting audio.
[0016]
In addition, the telephone of the present invention develops voice data input by a caller into voice frequency components, creates frequency conversion data that is voice data obtained by multiplying each voice frequency component by a predetermined magnification, and sends the data to the outside. This is a configuration having a frequency converter.
[0017]
Further, in the telephone of the present invention, the frequency converter is
A Fourier transform circuit that expands the audio data into combination data including the audio frequency component and its signal level;
An interpolation circuit that performs frequency conversion by multiplying each of the audio frequency components by the predetermined magnification while maintaining a signal level for the combination data received from the Fourier transform circuit,
An inverse Fourier transform circuit that receives the interpolator and creates the frequency transform data from the frequency-converted combination data,
May be provided.
[0018]
Further, the telephone according to the present invention may further include a synthesized voice identifier for specifying synthesized voice data indicating voice frequency characteristics similar to the voice data, and each voice frequency component of the voice frequency characteristics of the synthesized voice data corresponding to the synthesized voice identifier. A table containing a frequency conversion synthesized speech identifier indicating a voice frequency characteristic multiplied by a predetermined magnification is stored, and the frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier included in the encoded data obtained by encoding the speech data Is selected from the table, and a frequency converter for generating frequency conversion encoded data including the frequency conversion synthesized speech identifier is provided.
[0019]
In this case, the frequency converter comprises:
The synthesized speech identifier included in the encoded data, and an index separation for separating an excitation signal for minimizing an error between synthesized speech data of the synthesized speech identifier and speech data of the encoded data from the encoded data. Department and
A table including the synthesized speech identifier and a frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier is stored, and the frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier received from the index separation unit is selected from the table. A conversion unit;
An index synthesizing unit that synthesizes the frequency conversion synthesized voice signal received from the conversion unit and the excitation signal received from the index separation unit to create the frequency conversion encoded data,
May be provided.
[0020]
Further, in the telephone according to the present invention, the predetermined magnification may be a positive value smaller than one.
[0021]
On the other hand, the call method of the present invention for achieving the above object is to develop audio data received from the outside into audio frequency components,
Create frequency conversion data which is audio data obtained by multiplying each audio frequency component by a predetermined magnification,
The frequency conversion data is sent to audio output means for outputting audio.
[0022]
Further, the call method of the present invention expands voice data by a caller's input into voice frequency components,
Create frequency conversion data which is audio data obtained by multiplying each audio frequency component by a predetermined magnification,
The frequency conversion data is sent to the outside.
[0023]
Further, in the above-mentioned communication method of the present invention, the predetermined magnification may be a positive value smaller than 1.
[0024]
Further, the speech frequency conversion method of the present invention for achieving the above object comprises a synthesized speech identifier for specifying synthesized speech data having speech frequency characteristics similar to speech data and the synthesized speech identifier corresponding to the synthesized speech identifier. Providing a table including a frequency conversion synthesized voice identifier indicating a voice frequency characteristic obtained by multiplying each voice frequency component of the voice frequency characteristics of the data by a predetermined magnification,
Selecting the frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier included in the encoded data obtained by encoding the speech data from the table,
The frequency conversion encoded data including the frequency conversion synthesized speech identifier is created.
[0025]
(Action)
According to the present invention, by multiplying the audio frequency component of the audio data by a predetermined magnification, the audio frequency is shifted to the frequency range where the audio is easy to hear, and the audio converted to the audio frequency that is easy to hear is output from the audio output unit.
[0026]
Further, in the present invention, since the audio frequency component of the audio data is multiplied by the predetermined magnification, the audio data converted to a frequency that is easy to hear is transmitted to the outside. Therefore, even if the telephone at the communication destination does not have a function of converting the frequency of the received voice data, it can output voice converted to a frequency that is easy to hear.
[0027]
Further, in the present invention, since the audio data is once expanded into audio frequency components, and each audio frequency is multiplied by a predetermined magnification and frequency-converted, the audio frequency can be easily shifted to a frequency region where the audio frequency is easy to hear.
[0028]
Further, according to the present invention, since the table including the synthesized speech identifier and the frequency conversion synthesized speech identifier is provided, the frequency conversion synthesized speech identifier indicating the audio frequency characteristic obtained by multiplying each audio frequency of the audio frequency characteristic by a predetermined magnification can be easily obtained. Is specified.
[0029]
Further, according to the present invention, by multiplying the audio frequency by a positive value smaller than 1 as a predetermined magnification, audio data that is shifted to a lower frequency side as the audio frequency is higher is output. For this reason, it is possible to reduce listening mistakes that are likely to occur in voices having a high signal level of the high-frequency side voice frequency.
[0030]
BEST MODE FOR CARRYING OUT THE INVENTION
The telephone according to the present invention is characterized in that, by shifting the audio frequency of audio data to the lower frequency side, the audio frequency component in the higher frequency area, which is likely to be erroneously heard, is converted to the lower frequency side and output.
[0031]
(First embodiment)
A first embodiment of the telephone according to the present invention will be described. In the following, the same components as those in the related art are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0032]
FIG. 1 is a block diagram showing one configuration example of the telephone according to the present embodiment.
[0033]
In the telephone of this embodiment, the transmitting unit 210a has the same configuration as the conventional one, but the receiving unit 120b has a configuration in which the frequency converter 6 is provided between the decoder 5 and the D / A converter 7.
[0034]
Next, the frequency converter 6 will be described.
[0035]
FIG. 2 is a block diagram illustrating a configuration example of the frequency converter 6.
[0036]
As shown in FIG. 2, the frequency converter 6 includes an FFT (Fast Fourier Transform) circuit 31 for expanding audio data into audio frequency components, and an interpolation circuit for multiplying each of the expanded audio frequency components by a predetermined magnification. 32 and an IFFT (Inverse Fast Fourier) for creating frequency-converted data obtained by converting frequency-converted audio frequency components into audio data.
(Transform) circuit 33.
[0037]
The FFT circuit 31 develops the data into combination data composed of the frequency and the signal level by fast Fourier transform in order to check what frequency component is included in the audio digital data received every predetermined time.
[0038]
Upon receiving the combination data, the interpolation circuit 32 multiplies the audio frequency by a predetermined magnification while maintaining the signal level of each combination data to convert the audio data to an audio frequency shifted to a lower frequency side. Subsequently, combination data for supplementing the converted audio frequencies is created. Here, the predetermined magnification is a positive value smaller than 1 in order to shift the frequency to the lower frequency side.
[0039]
Upon receiving the frequency-converted combination data, the IFFT circuit 33 performs inverse Fourier transform to generate frequency conversion data obtained by converting the frequency-converted combination data into audio digital data.
[0040]
Next, an operation procedure of the telephone having the above configuration will be described.
[0041]
In FIG. 1, when a caller operates one telephone and can talk to the other telephone, a voice is input to the microphone 1 of the transmitting unit 210a. When a voice is input, the microphone 1 converts the voice into an electric signal, and sends out the converted voice signal to the A / D converter 2. When the A / D converter 2 receives the audio signal from the microphone 1, the A / D converter 2 converts the audio signal into audio digital data sampled at 10 KHz and sends it to the encoder 3. The encoder 3 encodes the audio digital data received from the A / D converter 2, and transmits the encoded data to the receiving unit 120b provided in another telephone via the transmission line 4.
[0042]
When receiving the encoded data from the encoder 3, the decoder 5 of the receiving unit 120 b provided in the communication destination telephone decodes the encoded data and sends out the audio digital data to the frequency converter 6.
[0043]
FIG. 3 is a flowchart showing the operation procedure of the frequency converter 6.
[0044]
As shown in FIG. 3, when the frequency converter 6 receives the audio digital data from the decoder 5 every predetermined time, the FFT circuit 31 divides the 10 kHz frequency region of the audio digital data by 512 points into 19.5 Hz. Fast Fourier transform is performed at the resolution of (1) to convert to frequency components (step SA1). After the conversion, the combination data including the frequency and the signal level is sent to the interpolation circuit 32 (step SA2). Upon receiving the combination data from the FFT circuit 31, the interpolation circuit 32 converts the frequency into a frequency shifted to a lower frequency side by multiplying the frequency by a predetermined magnification while maintaining the signal level of each combination data (step SA3). Subsequently, combination data for compensating for the frequency interval after the conversion is created (step SA4), and the combination data is sent to the IFFT circuit 33. Upon receiving the combination data from the interpolation circuit 32, the IFFT circuit 33 performs inverse Fourier transform on the combination data to create frequency conversion data (step SA5), and sends the frequency conversion data to the D / A converter 7 (step SA6). ).
[0045]
Upon receiving the frequency conversion data from the frequency converter 6, the D / A converter 7 converts the frequency conversion data from a digital signal to an analog signal and sends an analog audio signal to the speaker 8 as in the related art. When the speaker 8 receives the audio signal from the D / A converter 7, the speaker 8 performs electroacoustic conversion on the audio signal and outputs the audio signal.
[0046]
Next, the frequency conversion by the interpolation circuit 32 will be specifically described in the case of frequency conversion of frequency characteristic data.
[0047]
FIG. 4 is a graph showing an example of the frequency characteristic data, and FIG. 5 is a graph showing the frequency characteristic data shown in FIG. 4 after frequency conversion. The horizontal axis of the graph indicates the frequency [Hz], and the vertical axis indicates the signal level [dB].
[0048]
The graph shown in FIG. 5 is obtained by multiplying each audio frequency by 0.8 as a predetermined magnification while keeping the signal level, and plotting the combined data including the audio frequency and its signal level shown in FIG. . Here, attention is paid to the frequency conversion of the local maximums near the audio frequencies of 1.1 KHz and 4.5 KHz shown in FIG. As shown in FIG. 5, the local maximum at a frequency of about 1.1 KHz has a converted audio frequency of 0.9 KHz, and has moved to the lower side by 0.2 KHz. On the other hand, as shown in FIG. 5, the converted maximum audio frequency of the local maximum near the audio frequency of 4.5 KHz is 3.6 KHz, and is shifted to the lower side by 0.9 KHz.
[0049]
As described above, the entire waveform shown in FIG. 4 is shifted to the left of the graph at the same magnification to become the waveform shown in FIG. Also, the higher the audio frequency, the greater the frequency shifts to the lower frequency side. In this case, the ratio between the maximum parts of the audio frequency shown in FIG. 4 is the same in the waveform shown in FIG.
[0050]
In the present embodiment, since the receiving unit is provided with the above-described frequency converter 6, the audio frequency component of the audio digital data is shifted to the low frequency side, so that the audio frequency is shifted from the high frequency side to the low frequency side. Sound is output from the speaker. For this reason, it is possible to reduce mistakes in listening by seniors with respect to voice having a high signal level of the high-frequency side voice frequency.
[0051]
Further, since the audio digital data is once expanded into audio frequency components and then subjected to frequency conversion, the audio frequency can be easily shifted to a lower frequency side.
[0052]
Further, by setting the predetermined magnification to a positive value smaller than 1, a higher audio frequency can be shifted to a lower frequency side. On the other hand, if the predetermined magnification is set to a positive value larger than 1, the audio frequency on the lower frequency side can be shifted to the higher frequency side more. In this case, the voice is easily heard by a person who has difficulty in hearing the voice of the low frequency side audio frequency.
[0053]
(Second embodiment)
In this embodiment, the frequency converter 6 of the first embodiment is provided on the transmitting side.
[0054]
This embodiment will be described. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0055]
FIG. 6 is a block diagram showing a configuration example of a telephone according to the second embodiment.
[0056]
In the telephone of this embodiment, the receiving unit 220b has the same configuration as the conventional telephone, but the configuration of the transmitting unit 310 is different. As shown in FIG. 6, the transmission unit 310a has a configuration in which the frequency converter 6 is provided between the A / D converter 2 and the encoder 3.
[0057]
The operation of the telephone according to the present embodiment will be described.
[0058]
In FIG. 6, when the caller operates one of the telephones and becomes able to talk with the other telephone, a voice is input to the microphone 1 of the transmitting unit 310a. When a voice is input, the microphone 1 sends the voice signal to the A / D converter 2. When the A / D converter 2 receives the audio signal from the microphone 1, the A / D converter 2 sends audio digital data obtained by converting the audio signal from an analog signal to a digital signal to the frequency converter 6. Upon receiving the audio digital data from the A / D converter 2, the frequency converter 6 expands the audio digital data into audio frequency components and shifts the audio frequency to a lower frequency band, as in the first embodiment. The generated frequency conversion data is sent to the encoder 3.
[0059]
Thereafter, as in the first embodiment, the encoder 3 encodes the frequency conversion data received from the frequency converter 6, and transmits the encoded data via the transmission line 4 to the receiving unit 220b provided in another telephone. Send to
[0060]
In this embodiment, since the transmission unit is provided with the frequency converter 6 shown in the first embodiment, the audio frequency component of the audio digital data to be transmitted to the telephone at the communication destination is shifted to a lower frequency side. The digital audio data whose frequency is shifted from the high frequency side to the low frequency side is encoded and transmitted to the telephone at the communication destination. Therefore, even if the receiving telephone does not include the frequency converter in the receiving unit, the telephone outputs the audio whose audio frequency is shifted from the high frequency side to the low frequency side, and the signal level of the high frequency audio frequency is large. About, it is possible to reduce mistakes in listening by seniors.
[0061]
In the first and second embodiments, the encoding method used in the encoder 3 and the decoder 5 is, for example, ITU-T G.264. 722 SB-ADPCM can be used.
[0062]
In the first and second embodiments, the FFT circuit 31 is used as the frequency expanding means constituting the frequency converter 6, but a discrete Fourier transform (DFT) circuit may be used. The IFFT circuit 33 may be an inverse discrete Fourier transform (IDFT) circuit.
[0063]
Further, in the first and second embodiments, the frequency converter 6 creates the frequency conversion data from the audio digital data. However, the frequency converter 6 may create the frequency conversion data from the audio signal.
[0064]
Furthermore, in the first and second embodiments, the audio data transmitted and received between the telephones is digital audio data, but may be an audio signal. Although audio digital data is encoded and transmitted, it may be transmitted and received without encoding.
[0065]
(Third embodiment)
In the present embodiment, information indicating audio frequency characteristics is extracted from encoded data, converted into encoded data in which each audio frequency is shifted to a lower frequency side, and transmitted to the outside.
[0066]
The configuration of the present embodiment will be described. In the first and second embodiments described above, the case where a waveform coding method such as SB-ADPCM is used, but in this embodiment, CELP (Code-Excited Linear) is used as a hybrid coding method.
A description will be given of a case in which a Prediction coding method is used.
[0067]
FIG. 7 is a block diagram showing one configuration example of the telephone according to the present embodiment, and shows a transmitting unit 410a of one telephone and a receiving unit 420b of the other telephone. Note that one of the telephones has a receiving unit having the same configuration as the receiving unit 420b of the other telephone, and the other telephone has a transmitting unit of the same configuration as the transmitting unit 410a of the one telephone. Are omitted. In the following, the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0068]
As shown in FIG. 7, one of the telephone sets according to the present embodiment includes an encoder 13 for transmitting encoded data, which is data obtained by encoding voice data by a CELP encoding method, to the outside, and an encoding device for receiving the encoded data from the encoder 13. The transmission unit 410a includes a frequency converter 9 that shifts the audio frequency of the audio data of the data to a lower frequency side. Further, the receiving unit includes a decoder 15 for decoding the encoded data encoded by the CELP encoding method. The CELP coding method is disclosed in detail in, for example, Japanese Patent Application Laid-Open No. H8-6597.
[0069]
Next, the configuration of the encoder 13 will be described in detail.
[0070]
The encoder 13 includes a linear predictive coding (LPC) filter that creates synthesized speech data having speech frequency characteristics similar to the input speech data, and minimizes an error between the synthesized speech data and the speech data. And a codebook for storing information to be performed. In the codebook, an excitation codebook in which excitation data that is information of ideal excitation is stored, an adaptive codebook in which adaptive data that is information of speech data input in the past is stored, and the excitation data and There is a gain codebook that stores gain data that is gain information for multiplying adaptive data.
[0071]
In the following, an identifier for excitation data in an excitation codebook is referred to as an excitation codebook index, an identifier for adaptive data in an adaptive codebook is referred to as an adaptive codebook index, and gain data in a gain codebook is referred to as an index. The identifier is called a gain codebook index. A signal including information on the excitation codebook index, the adaptive codebook index, and the gain codebook index is referred to as an excitation signal.
[0072]
The encoder 13 also generates synthesized speech data created by the LPC filter and a linear prediction coefficient VQ (Vector Quantization) index (hereinafter simply referred to as a synthesized speech data) for identifying the synthesized speech data corresponding to the synthesized speech data. (Referred to as “VQ index”).
[0073]
Upon receiving the voice data, the encoder 13 selects a VQ index for specifying the synthesized voice data created by the LPC filter from the voice spectrum conversion table. Subsequently, an excitation signal is created by selecting an index from each of the above codebooks so that an error between the VQ index and the audio data is minimized, and encoded data in which the VQ index and the excitation signal are combined is created.
[0074]
The decoder 15 stores the speech spectrum conversion table, the excitation codebook, the adaptive codebook, and the gain codebook. Then, the voice frequency characteristic is specified from the voice spectrum conversion table by the received VQ index, and the sound source data, the adaptive data, and the gain data are specified from the various codebooks by the received excitation signal, and the voice data is created. The data is sent to the D / A converter 7.
[0075]
Next, the configuration of the frequency converter 9 will be described in detail.
[0076]
FIG. 8 is a block diagram showing a configuration example of the frequency converter shown in FIG.
[0077]
The frequency converter 9 separates the input coded data into a VQ index and an excitation signal, and an index separating unit 91, and a frequency indicating a voice frequency characteristic obtained by shifting each voice frequency of a voice frequency characteristic specified by the VQ index. The configuration includes a linear prediction filter coefficient VQ index conversion unit (hereinafter, simply referred to as “VQ index conversion unit”) 92 for converting to a conversion VQ index, and an index synthesis unit 93 for synthesizing the frequency conversion VQ index and the excitation signal. .
[0078]
The VQ index conversion unit 92 stores a VQ index conversion table for shifting each audio frequency of the audio frequency characteristic specified from the VQ index from a high frequency side to a low frequency side at a predetermined magnification. The VQ index conversion table describes frequency conversion VQ indexes corresponding to the VQ indexes. The predetermined magnification is a positive value smaller than one.
[0079]
Upon receiving the VQ index from the index separation section 91, the VQ index conversion section 92 selects a frequency conversion VQ index corresponding to the VQ index in the VQ index conversion table and sends it to the index synthesis section 93.
[0080]
The index synthesizing unit 93 synthesizes the frequency conversion VQ index received from the VQ index conversion unit 92 and the excitation signal received from the index separation unit 91 to create frequency conversion encoded data, and transmits the frequency conversion encoded data. It is sent to the outside via the path 4.
[0081]
Next, an operation procedure of the telephone having the above configuration will be described. Note that the predetermined magnification is 0.8. In the following, a detailed description of the same operations as those of the telephones of the first and second embodiments will be omitted.
[0082]
Upon receiving the audio data from the A / D converter 2, the encoder 13 of the transmitting unit 410a selects a VQ index for specifying the synthesized audio data created by the LPC filter from the audio spectrum conversion table. Subsequently, an excitation signal is created by selecting an index from each codebook so that an error between the VQ index and the audio data is minimized, and the encoded data obtained by combining the VQ index and the excitation signal is transmitted to the frequency converter 9. Send out.
[0083]
FIG. 9 is a flowchart showing the operation procedure of the frequency converter 9.
[0084]
As shown in FIG. 9, when receiving the encoded data from the encoder 13, the index separating unit 91 of the frequency converter 9 converts the encoded data into a VQ index, an excitation codebook index, an adaptive codebook index, and a gain code. It is separated into an excitation signal including a book index (step SB1). Subsequently, the VQ index is sent to the VQ index conversion unit 92, and the excitation signal is sent to the index synthesis unit 93.
[0085]
Upon receiving the VQ index from the index separation unit 91, the VQ index conversion unit 92 selects a frequency conversion VQ index corresponding to the VQ index in the VQ index conversion table and sends it to the index synthesis unit 93 (step SB2). The frequency conversion VQ index selected here is obtained by multiplying each audio frequency of the audio frequency characteristic specified by the input VQ index by 0.8, and shifting the audio frequency from the high frequency side to the low frequency side. It is shown.
[0086]
The index synthesizing unit 93 synthesizes the frequency conversion VQ index received from the VQ index conversion unit 92 and the excitation signal received from the index separation unit 91 to create frequency conversion encoded data (step SB3). The encrypted data is transmitted to the decoder 15 of another telephone via the transmission line 4 (step SB4).
[0087]
When the decoder 15 receives the frequency conversion VQ index and the excitation signal from the frequency converter 9 of one of the telephones, the decoder 15 specifies the audio frequency characteristics from the audio spectrum conversion table using the frequency conversion VQ index, and uses the excitation signal to generate the sound source from various codebooks. The audio data is created by specifying the data, the adaptation data, and the gain data, and the audio data is sent to the D / A converter 7.
[0088]
Upon receiving the audio data from the decoder 15, the D / A converter 7 converts the digital signal into an analog signal and sends out the analog audio signal to the speaker 8. Upon receiving the audio signal from the D / A converter 7, the speaker 8 performs electroacoustic conversion on the audio signal, and the audio having the audio frequency characteristics of the audio input by the microphone 1 multiplied by 0.8. To output.
[0089]
In the present embodiment, by providing the above-described frequency converter 9 in the transmission unit, the frequency conversion coded data indicating the audio frequency characteristic in which the audio frequency is shifted from the high frequency side to the low frequency side is transmitted to another telephone. . For this reason, the audio frequency component of the audio due to the audio data decoded by the decoder of the other telephone shifts to the low frequency side, and the elderly person can reduce mistakes in the audio with a large signal level of the high frequency audio frequency.
[0090]
Further, since the VQ index conversion unit 92 includes the VQ index conversion table, it is possible to easily specify an index for shifting each audio frequency of the audio frequency characteristic to the lower frequency side. Therefore, the frequency conversion is performed faster, and the call can be performed more smoothly.
[0091]
Further, by setting the predetermined magnification to a positive value smaller than 1, a higher audio frequency can be shifted to a lower frequency side. On the other hand, if the predetermined magnification is set to a positive value larger than 1, the audio frequency on the lower frequency side can be shifted to the higher frequency side more. In this case, the voice is easily heard by a person who has difficulty in hearing the voice of the low frequency side audio frequency.
[0092]
Note that the frequency converter 9 may be provided in a receiving unit of the telephone.
[0093]
FIG. 10 is a block diagram showing a configuration example of a telephone provided with the frequency converter shown in FIG. 8 in a receiving unit, and shows a transmitting unit 510a of one telephone and a receiving unit 520b of the other telephone.
[0094]
In FIG. 10, when the frequency converter 9 of the receiving unit 520b receives the encoded data via the transmission path 4, as described above, the frequency converter 9 corresponding to the VQ index included in the encoded data in the VQ index conversion table is used. The VQ index is selected to create frequency conversion encoded data, and the frequency conversion encoded data is sent to the decoder 15. Thus, by providing the above-described frequency converter 9 in the receiving unit, even if the transmitting unit of the communication destination telephone does not include the frequency converter, the audio obtained by multiplying each audio frequency of the audio frequency characteristic by a predetermined magnification is used. The frequency conversion encoded data indicating the frequency characteristics is transmitted to the decoder 15.
[0095]
In the third embodiment, the frequency converter 9 may be provided in one of the encoder 13 and the decoder 15.
[0096]
Further, the first to third embodiments may be applied to a portable telephone provided with a wireless transmission / reception unit capable of wireless communication with each other.
[0097]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0098]
The present invention includes a frequency converter that shifts an audio frequency of an input audio signal to a low frequency side and outputs the shifted audio frequency. When audio including a high frequency audio frequency component is input from a microphone, the high frequency audio frequency A sound whose component is shifted to the lower frequency side is output. For this reason, the high-frequency sound frequency components that are difficult for the elderly to hear are shifted to the low-frequency side, so that mistakes in the conventional listening are reduced, and the communication between the callers becomes smooth.
[0099]
Further, the present invention is effective not only for the elderly but also for those who have difficulty in hearing the sound of the high-frequency sound frequency.
[0100]
Further, by storing in advance a table including a VQ index for specifying synthesized voice data indicating voice frequency characteristics similar to voice data and a frequency conversion VQ index corresponding to the VQ index, the received coded data Encoded data including information on audio frequency characteristics obtained by multiplying each audio frequency of the audio frequency characteristics by a predetermined magnification is easily created. Therefore, the frequency conversion is performed faster, and the call can be performed more smoothly.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of a telephone according to the present invention.
FIG. 2 is a block diagram illustrating a configuration example of a frequency converter according to the present invention.
FIG. 3 is a block diagram showing an operation procedure of the frequency converter shown in FIG.
FIG. 4 is a graph showing frequency characteristic data before frequency conversion.
FIG. 5 is a graph showing the frequency characteristic data shown in FIG. 4 after frequency conversion.
FIG. 6 is a block diagram illustrating a configuration example of a telephone according to a second embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration example of a telephone according to a third embodiment of the present invention.
FIG. 8 is a block diagram illustrating a configuration example of a frequency converter illustrated in FIG. 7;
9 is a flowchart showing an operation procedure of the frequency converter shown in FIG.
10 is a block diagram showing a configuration example of a telephone provided with the frequency converter shown in FIG. 8 in a receiving unit.
FIG. 11 is a block diagram showing a configuration example of a conventional telephone.
[Explanation of symbols]
1 microphone
2 A / D converter
3,13 encoder
4 Transmission line
5, 15 decoder
6, 9 frequency converter
7 D / A converter
8 Speaker
31 FFT circuit
32 interpolation circuit
33 IFFT circuit
91 Index separation unit
92 Linear prediction filter coefficient VQ index converter
93 Index Synthesizer
120b, 220b, 420b, 520b Receiver
210a, 310a, 410a, 510a Transmitter

Claims (10)

The audio data received from the outside is expanded into audio frequency components, frequency conversion data which is audio data obtained by multiplying each audio frequency component by a predetermined magnification, and transmitted to audio output means for outputting audio. Telephone with converter. A telephone having a frequency converter that expands voice data input by a caller into voice frequency components, generates frequency conversion data that is voice data obtained by multiplying each voice frequency component by a predetermined magnification, and sends the data to the outside. The frequency converter,
A Fourier transform circuit that expands the audio data into combination data including the audio frequency component and its signal level;
An interpolation circuit that performs frequency conversion by multiplying each of the audio frequency components by the predetermined magnification while maintaining a signal level for the combination data received from the Fourier transform circuit,
An inverse Fourier transform circuit that receives the interpolator and creates the frequency transform data from the frequency-converted combination data,
The telephone according to claim 1 or 2, further comprising: Synthesized voice identifier for specifying synthesized voice data indicating voice frequency characteristics similar to voice data, and voice obtained by multiplying each voice frequency component of the voice frequency characteristics of the synthesized voice data corresponding to the synthesized voice identifier by a predetermined magnification. A table including a frequency conversion synthesized voice identifier indicating a frequency characteristic is stored, and the frequency conversion synthesized voice identifier corresponding to the synthesized voice identifier included in the encoded data obtained by encoding the voice data is selected from the table. A telephone having a frequency converter for creating frequency conversion encoded data including a frequency conversion synthesized speech identifier. The frequency converter,
The synthesized speech identifier included in the encoded data, and an index separation for separating an excitation signal for minimizing an error between synthesized speech data of the synthesized speech identifier and speech data of the encoded data from the encoded data. Department and
A table including the synthesized speech identifier and a frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier is stored, and the frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier received from the index separation unit is selected from the table. A conversion unit;
An index synthesizing unit that synthesizes the frequency conversion synthesized voice signal received from the conversion unit and the excitation signal received from the index separation unit to create the frequency conversion encoded data,
The telephone according to claim 4, comprising: The telephone according to any one of claims 1 to 5, wherein the predetermined magnification is a positive value smaller than one. Expands audio data received from outside into audio frequency components,
Create frequency conversion data which is audio data obtained by multiplying each audio frequency component by a predetermined magnification,
A communication method for transmitting the frequency conversion data to audio output means for outputting audio. Expands voice data from the input of the caller into voice frequency components,
Create frequency conversion data which is audio data obtained by multiplying each audio frequency component by a predetermined magnification,
A communication method for transmitting the frequency conversion data to the outside. 9. The communication method according to claim 7, wherein the predetermined magnification is a positive value smaller than one. Synthesized voice identifier for specifying synthesized voice data indicating voice frequency characteristics similar to voice data, and voice obtained by multiplying each voice frequency component of the voice frequency characteristics of the synthesized voice data corresponding to the synthesized voice identifier by a predetermined magnification. Provide a table including a frequency conversion synthesized speech identifier indicating the frequency characteristics,
Selecting the frequency conversion synthesized speech identifier corresponding to the synthesized speech identifier included in the encoded data obtained by encoding the speech data from the table,
A voice frequency conversion method for generating frequency conversion encoded data including the frequency conversion synthesized voice identifier.

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