JP2009258529A - Telephone call device and telephone call method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a telephone call device and a telephone call method, in which speech speed conversion effect is fully obtained, when a user performs transmission muting. <P>SOLUTION: The telephone call device includes: a speech speed conversion section 104 in which slow reproduction is performed by making a speech speed slow in speech received from a partner terminal under call; and a call muting determination section 103 which determines whether user's call speech is muted on the partner terminal. When the call muting is performed, a limit of delay time in speech speed conversion is made larger than that when muting is not performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a call device and a call method for making a voice call by connecting a plurality of bases such as a conference phone.

  The technology of speech speed conversion that changes the speed of the voice without changing the pitch of the voice is known from the past, and is widely used for voice reproduction devices such as IC (Integrated Circuit) recorders, telephones, televisions, radios, and the like. It's being used. The content of the speech speed conversion process is shown in (Patent Document 1), for example.

  A general processing configuration for converting speech into a slow speech speed will be described. FIG. 10 is a block diagram of a conventional speech speed conversion device. In FIG. 10, 201 is an audio pitch detection unit that detects the pitch (fundamental frequency) of an audio signal, 202 is an insertion waveform generation unit that extracts an audio waveform in units of the audio pitch period, and 203 is an input audio signal that represents the extracted pitch waveform It is a waveform connection part that expands the waveform in the direction of the time axis by inserting it periodically. The voiced signal waveform composed of the fundamental frequency and its overtones tends to repeat the same waveform periodically in pitch units, so this configuration should be converted to a slower speech speed without changing the pitch. Is possible.

  Consider a case where speech speed conversion processing is applied to a device that performs voice transmission / reception such as a communication device that requires real-time performance. For example, if the speech speed of the received voice is uniformly reduced and continuously reproduced, the delay time between the time when the received voice is actually generated and the playback time after the speech speed conversion (hereinafter simply referred to as the delay time). Will increase over time, causing serious problems in conversation. Therefore, when applied to such a device, special devices have been conventionally made. The concept will be described with reference to FIG. In real-time speech speed conversion processing, conversion is performed to slow down the speech interval (interval where the speech signal is present in the received signal), and compression is performed during the silent interval (interval where the speech signal is not present in the received signal). Therefore, the delay from the actual speech time is reduced.

  Even if the delay time is suppressed by using the above-described method, the delay time increases correspondingly if the voice signal continues with a voiced period. In a telephone device that requires real-time performance, a limit is set on this delay time to prevent an unnecessary delay. For example, here, the limit time is 1 second. If the delay time is accumulated up to 1 second, after that, playback is performed at the original speed without performing the speech speed conversion (see FIG. 12). During this time, the accumulated delay time remains, and when the delay is eliminated by input of a silent interval, the speech speed is converted until the delay reaches 1 second again. In this way, the minimum real-time property is maintained while performing the speech speed conversion.

  Further, as in (Patent Document 2) and (Patent Document 3), the speech rate conversion rate is calculated from the currently accumulated delay time and the maximum delay time or the maximum capacity of the memory for storing the delayed speech, and the maximum delay time is calculated. There is also a technology to adjust the speech rate conversion rate so as not to exceed.

  In addition, when a user makes a call using a communication device, both the user and the other party talk alternately, but there are many situations where the other party speaks unilaterally and the user continues to hear it. It can be seen. Especially in the case of a teleconference, during the presentation or explanation, the non-speaker mutes the transmission and keeps listening quietly. If speech speed conversion is used here, the other party's voice is played back slowly and can be easily heard.

When both parties speak alternately, there is a sufficient silent section from the other party's utterance to the next partner's utterance as shown in FIG. Therefore, the delay due to the speech speed conversion is eliminated each time a speech is made.
JP-A-5-257490 JP 2001-53835 A JP 2007-072045 A

  However, during mute, the other party speaks unilaterally, so there are few silent sections and the delay time reaches the limit immediately. By adjusting the speech rate conversion rate, it is possible to prevent the delay time from reaching the limit immediately, but as a result, it is not possible to reproduce slowly. In particular, during the transmission mute, the user is devoted to listening to the talk from the other party, so that the effect of the speech speed conversion cannot be sufficiently obtained, which is noticeable to the user and causes discomfort.

  Also, when muted, real-time performance is not required as in two-way calls. In the case of a two-way call, user A responds after listening to the other party's voice that has been played back slowly as shown in FIG. There will be a lot of time, making it difficult to talk smoothly. On the other hand, when the user A performs the transmission mute as shown in FIG. 14, the calling party B does not have to wait for a reply from the user A, so there is no need to worry about the delay time when speaking. .

  The present invention has been made in view of the above, and provides a call device and a call method that can sufficiently obtain a speech speed conversion effect when a user is performing mute transmission. Objective.

  In order to solve the above problems, the present invention provides speech speed conversion means for performing speech speed conversion for slowing down and reproducing the received speech received from a partner terminal during a call, and said speech speed conversion means by the speech speed conversion means. When conversion is performed, transmission mute determination means for determining whether or not to perform transmission mute without transmitting the user's transmitted voice to the counterpart terminal, and the transmission mute is performed by the transmission mute means. Delay time setting means for setting a delay time limit in the speech speed conversion when determined to be larger than when the transmission mute determination means determines not to perform the transmission mute. Is.

  While the user does not intend to make a two-way call by muting the transmitted voice during a call, priority is given to increasing the delay time limit to increase the efficiency of speech speed conversion, and the user can make a two-way call. When performing, speech speed conversion is performed according to the purpose of use, in which the limit of delay time is restored and priority is given to real-time performance.

  According to the present invention, when talking between the listener and the other party terminal, the limit of the delay time in the speech speed conversion is set to a range that maintains real-time characteristics, and when it is determined that the transmitted voice is muted. The setting is changed so that the limit of the delay time becomes longer than the above-described time. For this reason, even if it is played slowly, a certain delay time limit is maintained during two-way calls, so there is no stress on the call, and when sending mute, there is a limit on the delay time even if the other party speaks unilaterally. It is possible to maintain the intended speech rate conversion rate for a long time because it has become large.

  According to a first aspect of the present invention, there is provided a speech speed converting means for performing a speech speed conversion for reproducing the received voice received from the partner terminal at a lower speed, and when the speech speed conversion is performed by the speech speed converting means, A speech mute determination means for determining whether or not to perform a transmission mute that does not send the transmitted voice to the partner terminal, and a delay time in the speech speed conversion when the transmission mute determination means determines that the transmission mute is to be performed. Delay time setting means for setting the limit of the transmission time to be larger than the case where the transmission mute determination means determines that the transmission mute is not performed, and the user's transmission voice is muted Depending on the situation and when not muted, the speech speed conversion performance can be adapted.

  In a second aspect based on the first aspect, the delay time setting means sets the limit of the delay time in speech speed conversion to about 1 second when it is determined that the transmission mute means does not perform the transmission mute. Even if the speech speed of the received voice is reproduced slowly, the delay time due to the speech speed conversion is about 1 second or less, and the real-time property can be maintained in the conversation.

  In a third aspect based on the first aspect, the delay time setting means sets the limit of the delay time in the speech speed conversion to about 2 seconds when it is determined that the transmission mute means performs the transmission mute. When the user's transmitted voice is muted, the speech speed conversion functions well even when the delay time is longer than when the muted voice is not muted. Have.

  In a fourth aspect based on the first aspect, the speech speed conversion means reproduces the first speech speed conversion rate as the speech speed conversion rate to be reproduced and the second speech speed to be reproduced later than the first speech speed conversion rate. One of the two conversion rates is selectively set, and the user can select a large speech rate conversion rate and a small speech rate conversion rate according to the usage situation. It has an effect that the performance of the speech speed conversion can be adapted according to the speed conversion rate and whether or not the transmission mute is performed during a call.

  In a fifth aspect based on the fourth aspect, when the delay time setting means determines that the transmission mute determination means does not perform the transmission mute, the delay time setting means sets the limit of the delay time in the first speech speed conversion rate. The feature is that it is set to approximately 1 second, and even if the speech speed of the received voice is reproduced slowly, the delay time due to the speech speed conversion is approximately 1 second or less, and the real-time property can be maintained in the conversation. Has an effect.

  In a sixth aspect based on the fourth aspect, when the delay time setting means determines that transmission mute is performed by the transmission mute means, the delay time limit in the first speech speed conversion is approximately 3 seconds. When the user's transmitted voice is muted, the speech speed conversion functions well even when the delay time is longer than when it is not muted. It has the action.

  According to a seventh aspect, in the fourth aspect, when the delay time setting means determines that the transmission mute determination means does not perform the transmission mute, the delay time setting means sets the limit of the delay time in the second speech speed conversion rate. Even if the speech speed of the received voice is reproduced with the speech speed conversion rate B, the delay time due to the speech speed conversion is approximately 2 seconds or less, and the limit of the delay time is limited. Compared to the time of 1 second, the effect of speaking speed conversion can be maintained, and a certain degree of real time can be maintained in the conversation.

  In an eighth aspect based on the fourth aspect, when the delay time setting means determines that transmission mute is performed by the transmission mute means, the delay time limit in the second speech speed conversion is approximately 3 seconds. When the user's transmitted voice is muted, the speech speed conversion functions well even when the delay time is longer than when it is not muted. It has the action.

  Hereinafter, embodiments of the present invention will be described.

(Embodiment 1)
In the first embodiment, in a conference call or the like, the user can switch ON / OFF of slow playback, and can also instruct to mute the transmitted voice, and receive it from the counterpart terminal in response to this. By dynamically changing the limit amount of the received voice stored to convert the speech speed of the received voice, the delay time is shortened when the transmitted voice is not muted, and the transmitted voice is muted. A call device and a call method capable of taking a long delay time when the call is in progress will be described.

  FIG. 1 is an external view of a communication device according to Embodiment 1 of the present invention, and FIG. 2 is a top view of the communication device of FIG. 1 to 2, reference numeral 601 denotes a communication device, reference numerals 602 a to 602 d (hereinafter 602) denote microphones that collect user's voice, reference numeral 603 denotes a speaker that reproduces received voice, and reference numeral 604 denotes communication connected to the other line. Cable, 605 is a mute button for switching on / off muting of transmitted voice, 606 is a slow button for starting / ending speech speed conversion (slow playback), and 607 is an operation button for performing outgoing / incoming operations 608 is a display unit for displaying the state of the call.

  FIG. 3 is a diagram showing an example of a configuration when using the communication device according to Embodiment 1 of the present invention, and FIG. 4 is another example of a configuration when using the communication device according to Embodiment 1 of the present invention. FIG.

  In FIG. 3, 601a is a communication device used by speaker A, 601b is a communication device used by speaker B, 1201a and 1201b are gateways, and 1202 is the Internet. In the configuration example shown in FIG. 3, the two communication devices 601a and 601b are connected to the Internet 1202 via gateways 1201a and 1201b, respectively. In the case of FIG. 3, the audio signal transmitted / received between the call device 601a and the call device 601b is data obtained by packetizing a digital signal.

  In FIG. 4, reference numerals 1301a and 1301b denote connection lines connected to the communication devices 601a and 601b, respectively; 1302a and 1302b denote modems; 1303a and 1303b denote public line networks; A provider (indicated as ISP in the figure).

  3 and 4 are examples, and the configuration shown in FIG. 3 and the configuration shown in FIG. 4 may be mixed, or the modems 1302a and 1302b in FIG. You may have the structure connected only through the same public line. In addition, here, two units are used for a call, but three units and four units may be used for a multipoint call.

  FIG. 5 is a block diagram schematically showing a component configuration of the communication device according to Embodiment 1 of the present invention. In FIG. 5, 701 is a digital signal processor (Digital Signal Processor, hereinafter referred to as DSP) that performs various operations and control of peripheral devices, 702 is a communication path interface, 101 is a user interface, 703 is a memory, 705 is digital / analog. (Hereinafter referred to as D / A) converter, 704 is an analog / digital (hereinafter referred to as A / D) converter, 603 is a speaker, 602 is a microphone, 7011 is a reception signal input unit, 7012 is an audio signal output unit, and 7013 is a transmission unit. A speech signal output unit, 7014 is a transmission signal input unit, 7015 is a communication path, 7016 is a reception signal path, and 7017 is a transmission signal path.

  An outline of the operation of the call device in FIG. 5 will be described. The communication path interface 702 of the call device 601 is connected to one end of the communication path 7015, and transmits and receives a call signal (voice signal) with another call device (not shown) connected to the other end of the communication path 7015. A voice signal transmitted from another communication device connected to the other end is input from the reception signal input unit 7011 to the DSP 701 from the communication path 7015 via the communication path interface 702 and the reception signal path 7016.

  Here, for example, when a signal transmitted / received through the communication path 7015 is a digitized signal such as an IP (Internet Protocol) packet, the signal processed in the communication path interface 702 is, for example, a PCM (Pulse-Code Modulation). The received signal path 7016 is usually a serial bus or a parallel bus. When the communication path 7015 is an analog signal path such as PSTN (Public Switched Telephone Networks), an A / D converter is required inside the communication path interface 702 or the DSP 701. When the communication path interface 702 includes an A / D converter, all subsequent processing is performed using digital signals as before, and the reception signal path 7016 is usually a serial bus or a parallel bus. On the other hand, when the A / D converter is built in the DSP 701, the reception signal path 7016 is an analog signal line.

  The received voice whose speech speed has been converted by the DSP 701 is output from the audio signal output unit 7012, converted to an analog signal by the D / A converter 705, and reproduced from the speaker 603. Similarly, the user's transmitted voice is collected by the microphone 602, converted into a digital signal by the A / D converter 704, passed to the DSP 701 from the transmitted signal input unit 7014, and transmitted as a transmitted signal (audio signal). The signal is output from the signal output unit 7013, sent to the communication path interface 702 via the transmission signal path 7017, and sent to another communication apparatus. The user interface 101 and the memory 703 will be described later.

  A description will be given of a reception voice reproduction process in the communication device of the first embodiment configured as described above. FIG. 6 is a state transition diagram showing the operating state of speech speed conversion in Embodiment 1 of the present invention. Here, as a premise, it is assumed that the call device is connected to another point where the other party exists and is in a call (for example, during a conference call).

  In FIG. 6, here, the maximum time that may be delayed in order to maintain the real-time nature of the call is 1 second, and the maximum time that can be delayed due to the capacity of the buffer that stores the voice data is 2 seconds. Further, the average delay rate of speech speed when speech speed conversion is performed is set to 150%. The average speech rate conversion rate is 66.7% of the reciprocal. The reason for the average is that the degree of delay when the speech speed conversion is performed varies depending on the content of the voice.

  First, immediately after the start of the call, it may start from anywhere depending on the situation, but here, as shown in FIG. When the user depresses the mute button, there is no slow playback, and the transmission mute is performed 6B. Further, when the slow button is pressed from the state 6A, a state 6C in which the received voice is slowly played back is obtained. When the slow button is pressed from the state 6B, a state 6D in which both slow reproduction and transmission mute are performed is obtained. Even if the mute button is pressed from the state 6C, the state 6D is similarly obtained.

  These are irreversible transitions. For example, when the mute button is pressed from the state 6D, the state 6C is obtained. In this way, transition to each state is triggered by pressing the mute button or slow button.

  Since the state 6A and the state 6B do not perform slow reproduction, the maximum delay time is not set. In the state 6C, the maximum delay time is 1 second, and in the state 6D, the maximum delay time is 2 seconds. That is, if the mute button is pressed from the state 6C to the state 6D, the maximum delay time is changed from 1 second to 2 seconds. Conversely, if the mute button is pressed again from the state 6D to the state 6C, the delay time is changed from 2 seconds to 1 second. change. At this time, if the delay time has reached 2 seconds, the audio data for 1 second is discarded, or by playing back faster than the original speech speed by speech speed conversion, the delay time can be caught up to 1 second. .

  FIG. 7 is a block diagram schematically showing a functional configuration of the communication device according to Embodiment 1 of the present invention. In FIG. 7, reference numeral 101 denotes a user interface for a user to give a transmission mute instruction and a slow reproduction instruction, which corresponds to the mute button 605 and the slow button 606 in FIG. 102 is a slow playback determination unit that determines whether or not the slow button 606 is pressed, 103 is a transmission mute determination unit that determines whether or not the mute button 605 is pressed, and 104 is a slow button that is pressed by the slow playback determination unit 102. If it is determined that the mute button 605 is not pressed by the transmission mute determination unit 103, the maximum delay time of the slow playback is determined to be 1 second. A speech speed conversion unit 105 that sets 2 seconds is a transmission mute unit that does not send audio to the communication path when the transmission mute determination unit 103 determines that the mute button 605 is pressed.

  In the first embodiment, the slow playback determination unit 102, the transmission mute determination unit 103, the speech speed conversion unit 104, and the transmission mute unit 105 each correspond to a software program that operates on the DSP 701 in FIG. . The slow playback determination unit 102 and the speech speed conversion unit 104 calculate the received voice received by the DSP 701 from the communication path interface 702 according to a program stored in the memory 703, and perform the D / A via the voice signal output unit 7012. This is realized by outputting to the converter 705. The memory 703 is also used for collecting voice for speech speed conversion.

  FIG. 8 is a conceptual diagram of received voice when speech speed conversion is performed in the first embodiment. For example, as shown in FIG. 8 upper stage, "Hello Hello. Hello," said the other party speaks to the user. In this case, and to speak with "Hello Hello" is hanging about 3 seconds. Since the state 6A and the state 6B do not perform slow reproduction, they are reproduced to the user side at a normal speed as shown in the upper part of FIG. In the slow reproduction of the state 6C, if 150% of the average delay rate of speech speed, takes 3x1.5 = 4.5 seconds to play slowly "Hello Hello", 1.5 seconds delay from the original 3 seconds Will do. Actually, since the maximum delay time is 1 second, the delay time becomes 1 second during the reproduction, and the reproduction is started at a normal speed from there (the middle stage in FIG. 8). Although the speech speed conversion does not function sufficiently, the real-time property is maintained correspondingly, and the output of the slow playback is completed within one second at the worst after the other party finishes speaking. Therefore, the user can respond in 1 second after the other party finishes speaking even during slow playback. However, the delay time for the communication path and processing is ignored here.

  In the transmission mute during slow reproduction of the state 6D, since the maximum delay time is 2 seconds, talking it takes about 3 seconds the other party is a "Hello Hello" in the aforementioned speech speed conversion, delay time becomes 1.5 seconds However, since there is a margin up to the limit of the delay time, the received voice can be reproduced slowly until the end (lower part of FIG. 8). At this time, it takes 1.5 seconds for the slow call output to be completed after the call partner finishes speaking, but the user does not need to respond and the call partner does not need to wait for the user's response. The device can be used without stress. In the first embodiment, the average delay rate of speech speed is 150%, but the present invention is not limited to this.

  The maximum delay time for slow playback is 1 second for slow playback without transmission mute, and 2 seconds for slow playback with transmission mute, but is not limited to this. For example, an arbitrary time between 0.8 seconds and 1.2 seconds is selected as the maximum delay time when slow reproduction is performed without the transmission mute.

(Embodiment 2)
FIG. 9 is a state transition diagram showing an operation state of speech speed conversion in the second embodiment of the present invention.

  Although the flow of operation is almost the same as the state transition diagram of FIG. 6, in the second embodiment, there are two types of slow playback, type 1 and type 2. Here, the type 1 speech speed average delay rate is 140%, and the type 2 speech speed average delay rate is 180%. In addition, the maximum time that can be delayed is 3 seconds due to the capacity of the buffer for storing the audio data.

  First, immediately after the start of the call, it may start from anywhere depending on the situation, but here, as shown in FIG. When the user depresses the mute button, there is no slow playback, and the state 9B in which the transmission mute is performed is obtained.

  In the second embodiment shown in FIG. 9, not only the speech speed conversion can be switched on / off by pressing the slow button, but also in the order of OFF / type 1 / type 2 can be switched. When the slow button is pressed from the state 9A, the state 9C is entered in which type 1 slow reproduction is performed without muting the transmission. The maximum delay time in state 9C is 1 second. When the user is in state 9C, the user presses the mute button to transition to state 9D in which transmission is muted and type 1 slow playback is performed, and the delay time limit changes from 1 second to 3 seconds. As described above, the user does not need to respond after the output of the slow playback is completed, and the call partner does not need to wait for the user's response, so the call can be made without stress even if the delay time becomes large. I can do things. It is desirable to use the state 9C when the two-way talk well.

  When in the state 9C, when the user presses the slow button, the state transitions to the state 2E in which the transmission is not muted and the type 2 slow playback is performed. In state 9E, the transmission mute is not performed, but the maximum delay time is 2 seconds. Speech speed average delay rate of the state 9E is 180%, "Hello Hello" and speaks of in about 3 seconds, and the first and only takes 1.5 seconds, "Hello", 1.5x1.8 = 2 7 seconds, which is 1.2 seconds behind the original 1.5 seconds. That slow play is not heard at the time who said "Hello" and "Hello Hello". Thus, the slower the speech speed, the sooner the delay time exceeds 1 second. Therefore, the maximum delay time is set to 2 seconds in order to emphasize the duration of slow playback rather than the real-time performance. It is desirable to use the state 9E when the user does not speak much and wants to listen to the voice of the partner terminal slowly.

  When the user is in the state 9E, when the user presses the mute button, the transmission is muted and the state transitions to the state 2F in which type 2 slow playback is performed, and the delay time limit is changed from 2 seconds to 3 seconds. As a result, as in the state 9D, it is possible to make a call without stress even when the delay time is increased.

  In this way, by setting the maximum delay time individually depending on the degree of the speech rate conversion rate and the mute state, it is possible to create a system that can sufficiently obtain the effect of speech rate conversion according to the user's application. It becomes possible.

  In the second embodiment, the average speech rate delay rate is 140% for Type 1 and 180% for Type 2, but the present invention is not limited to this.

  Also, the maximum delay time for slow playback is 1 second for slow playback of type 1 without muting the transmission, 2 seconds for slow playback of type 2 without muting the transmission, The slow playback of 1 or type 2 is 3 seconds, but is not limited to this. For example, the maximum delay time for the type 1 slow playback without muting the transmission is selected as an arbitrary time between 0.8 seconds and 1.2 seconds.

  Furthermore, in the second embodiment, the slow playback 606 is switched in order of OFF / type 1 / type 2 with the slow button 606, but two buttons are provided so that the type 1 is pressed when one is pressed and the type 2 is pressed when the other is pressed. May be.

  The call device and the call method according to the present invention are sufficiently effective in converting the speech speed when the user is muting the transmission, and real-time performance is ensured when the muting is not performed. Therefore, it is suitable for a telephone conference system.

External view of communication apparatus in embodiment 1 Top view of communication apparatus according to Embodiment 1 FIG. 5 is a diagram illustrating an example of a configuration at the time of use in the first embodiment The figure which shows the other example of the structure at the time of use in Embodiment 1. Brook diagram showing component configuration of communication device in embodiment 1 State transition diagram of the first embodiment FIG. 3 is a block diagram showing a functional configuration of the telephone device according to the first embodiment. Conceptual diagram of real-time speech speed conversion in the first embodiment State transition diagram of the second embodiment Configuration diagram of conventional speech speed conversion circuit Conceptual diagram of real-time speech speed conversion processing Conceptual diagram of real-time speech speed conversion processing Conceptual diagram of real-time speech speed conversion processing Conceptual diagram of real-time speech speed conversion processing

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 User interface 102 Slow reproduction | regeneration determination part 103 Transmission mute determination part 104 Speech rate conversion part 105 Transmission mute part 601 Calling apparatus 602a-602d Microphone 603 Speaker 605 Mute button 606 Slow button 701 DSP
703 memory

Claims (16)

Speak speed conversion means for performing speech speed conversion for slowing down and reproducing the received voice received from the partner terminal, and when the speech speed conversion is performed by the speech speed conversion means, A transmission mute determination means for determining whether or not to perform a transmission mute that is not sent to the counterpart terminal, and a delay time in the speech speed conversion when the transmission mute determination means determines that the transmission mute is to be performed. And a delay time setting means for setting a limit of the delay time larger than the case where the transmission mute determination means determines that the transmission mute is not performed. The delay time setting means sets a limit of a delay time in the speech speed conversion to approximately 1 second when the transmission mute means determines that the transmission mute is not performed. 1. The communication device according to 1. 2. The delay time setting means sets a limit of a delay time in the speech speed conversion to about 2 seconds when it is determined that the transmission mute is performed by the transmission mute means. The communication device described in 1. The speech speed conversion means selects one of two types, ie, a first speech speed conversion ratio to be reproduced and a second speech speed conversion ratio to be reproduced later than the first speech speed conversion ratio. The call device according to claim 1, wherein the call device is selectively set. The delay time setting means sets the limit of the delay time in the first speech speed conversion rate to approximately 1 second when the transmission mute determination means determines that the transmission mute is not performed. The call device according to claim 4, wherein: The delay time setting means sets a limit of a delay time in the first speech speed conversion to about 3 seconds when the transmission mute means determines that the transmission mute is to be performed. The communication device according to claim 4. The delay time setting means sets the limit of the delay time in the second speech rate conversion rate to approximately 2 seconds when the transmission mute determination means determines that the transmission mute is not performed. The call device according to claim 4, wherein: The delay time setting means sets the limit of the delay time in the second speech speed conversion to about 3 seconds when the transmission mute means determines that the transmission mute is to be performed. The communication device according to claim 4. Performs speech speed conversion for slowing down the playback speed of the received voice received from the partner terminal, and mutes the transmission of the user's transmitted voice to the partner terminal when the speech speed conversion is performed. When the transmission mute is determined to be performed, the delay time limit in the speech speed conversion is set larger than the case where it is determined not to perform the transmission mute. Call method. The call method according to claim 9, wherein when it is determined that the transmission mute is not performed, a limit of a delay time in the speech speed conversion is set to about 1 second. 10. The call method according to claim 9, wherein when it is determined that the transmission mute is to be performed, a limit of a delay time in the speech speed conversion is set to approximately 2 seconds. One of the two types, the first speech rate conversion rate and the second speech rate conversion rate that is played back slower than the first speech rate conversion rate, is selectively set as the speech rate conversion rate to be reproduced. The calling method according to claim 9. 10. The call method according to claim 9, wherein when it is determined that the transmission mute is not performed, a limit of a delay time in the first speech rate conversion rate is set to approximately 1 second. 10. The calling method according to claim 9, wherein when it is determined that the transmission mute is to be performed, a limit of a delay time in the first speech speed conversion is set to about 3 seconds. 10. The call method according to claim 9, wherein when it is determined that the transmission mute is not performed, a limit of a delay time in the second speech speed conversion rate is set to approximately 2 seconds. 10. The call method according to claim 9, wherein when it is determined that the transmission mute is performed, a limit of a delay time in the second speech speed conversion is set to about 3 seconds.

Images