JP2001077908A - Voice communication apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide voice communication apparatus that has satisfactory speech quality immediately after the start of a portable phone speech. SOLUTION: When a central control circuit outputs a synthesized voice to a reception channel (S10), a reception gain, an echo path gain and a transmission gain area calculated and a semi-loop gain is calculated (S12-S18). Whether this half-loop gain is smaller than unity is discriminated (S20), and when this discrimination (20) is a negation, the half-loop gain is adjusted to be the unity or smaller (S22), and when value of the half-loop gain is converged within a prescribed range, the converged half-loop gain value is stored, and when a speech of the portable phone is started, a voice signal received from the portable phone is controlled by using the stored half-loop gain value. Thus, pleasant communication without being affected by an acoustic echo can be conducted starting at the moment of the use of the portable phone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voice communication device having a hands-free function for transmitting and receiving without a portable telephone.

[0002]

2. Description of the Related Art Conventionally, a so-called hands-free function has been used in a navigation device, in which a speaker and a sound collecting microphone provided in advance can be used for transmitting and receiving without holding a portable telephone. Some are provided.

[0003] In the navigation device having the hands-free function, the sound of the other party output from the speaker is collected again by the sound collecting microphone and re-transmitted to the other party, thereby generating an acoustic echo or the like. A part of the voice input from the sound collecting microphone and transmitted to the other party is reflected on the other party, and an electric echo or the like output from the speaker again via the other party's mobile phone becomes a problem.

[0004] Therefore, in this navigation device,
Devices for canceling these echoes are attached, and these devices are called an acoustic echo canceller (hereinafter, referred to as “AEC”) and a line echo canceller (hereinafter, referred to as “LEC”).

[0005] These echo cancellers are, for example, AEC
In the following, the impulse response (time during which the sound is transmitted through the echo path) of the sound path (hereinafter referred to as “echo path”) until the sound output from the speaker is collected by the sound collecting microphone, and Estimate the amplitude of the voice signal of the other party to be picked up, and based on these, output the received voice signal (the voice signal transmitted from the mobile phone to the speaker) and output it from the speaker input to the microphone. A pseudo echo corresponding to the reproduced voice is generated, and the pseudo echo is attenuated by adding the pseudo echo to the transmission voice signal (the voice signal output from the sound collecting microphone to the mobile phone) in the opposite phase. For a detailed description of this echo canceller, see, for example, the document “Digital processing in information and communication (Shokodo, November 25, 1987, pp. 1).
63 to 176 ", and a description thereof will be omitted.

On the other hand, as shown in FIG. 4, a LEC is a pseudo echo (AEC 46) applied to an input signal from an interface 28 for connecting a mobile phone to the navigation apparatus 1.
(This is different from the pseudo echo generated in step (1).) By the way, a conventional navigation device is provided with a device that varies the amplitude of an input audio signal under a preset condition and transmits the signal on a transmission channel or a reception channel. Note that these devices include an automatic gain control (hereinafter, referred to as "AGC") for attenuating or amplifying an input audio signal to a constant amplitude regardless of its amplitude and outputting the amplified signal, and an output from a speaker. In order to adjust the volume of the audio to be reproduced, a volume adjustment device or the like that attenuates or amplifies the audio signal may be used.

The gain of each of these AGC and volume adjustment devices is individually adjusted independently of other devices (components). Therefore, the gain of the AGC or volume adjustment device and the sound passing through the echo path (in the case of LEC) The loop gain (gain along the loop in FIG. 4), which is the sum of the gain and the gain of the audio signal, sometimes becomes 1 or more, causing oscillation and howling. In the echo canceller, since the echo impulse response and / or the amplitude of the voice transmitted through the echo path are estimated to cancel the echo, the estimated impulse response and / or the amplitude are reduced to the actual values. They do not always match, so if the loop gain is 1 or more, the effect of the echo sometimes remains.

In recent navigation devices, AE
In order to individually reduce the effects of the echoes for which C or LEC could not be canceled, instead of the loop gain described above, one of the echo cancellers is included, as shown by the dotted line in FIG. In some cases, loop gain control is performed so that the gain of a half loop not included (hereinafter, referred to as “half loop gain”) becomes 1 or less.

[0009]

In a conventional navigation device having a hands-free function, the distance between the sound-collecting microphone and the speaker is undefined, so that the impulse response of the echo path and the amplitude of the sound transmitted through the echo path are also undefined. is there. Therefore, conventionally, when a mobile phone is used, the above-described problems such as oscillation and howling have been avoided by estimating the impulse response and amplitude in the echo canceller and calculating the loop gain.

However, since it takes time to determine the optimum gain by loop gain control in particular, the effect of echo, howling, etc. remains until a certain time elapses from the start of the call, and the start of the call. There was also a problem that good call quality could not be obtained from time to time.

Therefore, the present invention solves the above problem,
It is an object of the present invention to provide a voice communication device having a relatively good call quality from the start of a mobile phone call.

[0012]

According to the first aspect of the present invention, a half-loop gain is controlled to 1 or less before using a portable telephone, so that an optimal function for each function can be achieved. Since the gain is obtained, at least the acoustic echo is not generated when the mobile phone is used, and high quality communication free from the influence of the acoustic echo can be performed from the start of the call.

Next, according to the voice communication apparatus of the present invention, the optimum half loop gain value can be obtained by repeatedly calculating the half loop gain until the half loop gain converges to a predetermined value or less. Can be more reliably reduced. Note that, as in the voice communication device according to the third aspect, a speaker commonly used as a speaker used for a navigation device may be used.

Next, according to the voice communication device of the present invention, before using the mobile phone, the half loop gain is 1 or less by using the voice signal other than the received voice signal output from the mobile phone. And the optimal gain for each function is obtained, so that when using a mobile phone, at least no acoustic echo is generated. It can be performed.

Further, when the voice communication device according to the fourth aspect is used, since a half-loop gain has already been calculated when talking on the mobile phone, the information processing in the voice communication device using the mobile phone is performed. Burden can be reduced.
The first transmitting means or the second transmitting means according to claim 4 includes an automatic gain control for attenuating or amplifying the amplitude of the input audio signal to a predetermined constant amplitude, and a volume of the audio output from the speaker. A device that adjusts the amplitude of the received audio signal or the transmitted audio signal with its own settings, such as a volume device for adjusting the audio signal, is applicable.

Further, as in the voice communication device according to the fifth aspect, the speaker of the navigation device may be commonly used as the voice output means.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Here, FIG. 1 is a block diagram showing an entire configuration of a navigation device to which the present invention is applied.

The navigation apparatus 1 of this embodiment provides a navigation voice for notifying a driver of a traveling direction, a traveling distance, a distance to a destination, and the like of a vehicle when the vehicle approaches an intersection or a branch road. A voice storage unit 10 storing
A position detector 12 for detecting the current position of the vehicle, and a CD-R
A map data input device 14 for inputting map data stored in an OM or the like, an operation switch group 16 for inputting various commands to the device 1, a VICS (Vehicle Info)
rmation and Communication System: an external information input device 1 for inputting road traffic information transmitted from a road traffic information communication system, information from the Internet, etc.
8, an external memory 20 backed up by a power supply (not shown), a display device 22 for displaying a map, the current position of the vehicle, and other various information, and a speaker 24 for outputting a received voice of a mobile phone and a navigation voice. And a remote control sensor 26 for inputting various commands to the device 1 transmitted from a remote control terminal (hereinafter, referred to as a “remote control”), and a mobile phone connected thereto to transmit various signals including audio signals. An interface 28 for inputting and outputting to and from a mobile phone is connected to a control circuit 40, which will be described later, via a dedicated cable, and collects sound emitted from a position more distant than when using a telephone with a normal handset. A control circuit 4 that inputs and outputs various signals between the sound collection microphone 30 that can perform the various processes and the various devices 10 to 30.
0.

Here, the position detector 12 is a GPS (Glob)
al Positioning System) receives the transmitted radio wave from the satellite via the GPS antenna,
A GPS receiver 12a for detecting speed and the like, and a gyroscope 12 for detecting the magnitude of a rotational motion applied to the vehicle
b, a distance sensor 12c composed of a vehicle speed sensor, a wheel sensor, and the like, for detecting a traveling distance of the vehicle, and a geomagnetic sensor 12d for detecting an absolute azimuth based on geomagnetism.

The control circuit 40 includes a CPU, a ROM,
ASIC (Application Specific) with RAM function
IC: a central control circuit composed of a well-known microcomputer composed of a specific use IC), a current position of the vehicle based on each detection signal from the position detector 12 and the external information input device 18, and a map. Data input device 1
A process of displaying a map or the like near the current position read through the display device 4 on the display screen of the display device 22, a so-called navigation process of setting a route to be driven on the map, and providing route guidance according to the set route. And various other processes, and a hands-free process described below for using a mobile phone without holding it. In the navigation processing described above, route guidance is performed using voice. In this navigation processing, when the vehicle arrives at a point to be guided, for example, when the vehicle approaches an intersection, the traveling direction is announced by voice, and the navigation voice stored in the voice storage unit 10 is synthesized to provide guidance. Synthesized voice (corresponding to “audio signal other than received voice” of the present invention) is created, and the synthesized voice is output from speaker 24.

Next, of the navigation device 1 configured as described above, components required for executing the hands-free processing will be described in further detail. Here, FIG. 2 is a circuit diagram showing components of the navigation device 1 necessary for executing the hands-free processing.
In this circuit diagram, the mobile phone and the navigation device 1 are shown.
Only the circuit for transmitting and receiving the audio signal among the signals transmitted and received between and is shown.

First, the navigation device 1 of the present embodiment
Component 1a for executing a hands-free process
(Hereinafter simply referred to as “component 1a”).
0, a speaker 24, an interface 28 for connecting the mobile phone to the component 1a, and a sound collecting microphone 30.

The control circuit 40 includes a central control circuit 42 including a CPU and the like, and a so-called electric echo generated when a part of the sound input to the interface 28 and the sound collecting microphone 30 is output to the speaker 24 again. And a line echo canceller 44 (hereinafter referred to as "LEC 44") for canceling the so-called acoustic echo generated when the sound collecting microphone 30 picks up a part of the sound output from the speaker 24. An acoustic echo canceller 46 (hereinafter, referred to as “AEC 46”) is provided. The control circuit 40 is provided on a receiving channel from the output terminal O of the interface 28 to the speaker 24, adjusts the amplitude of the audio signal output from the output terminal O, and
4 and a down auto gain control 50 (hereinafter referred to as “down AGC”) for controlling an audio signal suitable for output from
50 "), provided on a transmission channel from the sound collecting microphone 30 to the input terminal P of the interface, and adjusting the amplitude of the audio signal output from the sound collecting microphone 30.
An upstream auto gain control 48 (hereinafter referred to as "uplink AGC 48") for controlling the audio signal to an audio signal suitable for transmission via a mobile phone.
Furthermore, the control circuit 40 inverts the pseudo echo output from the LEC 44 to the signal output from the output terminal O and superimposes the same on the reception channel. A down attenuator 56 for adjusting the gain of an audio signal to be transmitted (hereinafter referred to as a “received audio signal”), a volume unit 57 for adjusting the volume of the audio output from the speaker, and an output from the AEC 46 An up-summer (also referred to as an adder or an adding means) 52 for inverting and superimposing the pseudo echo on the signal output from the sound collecting microphone 30, and an audio signal transmitted on a transmission channel (hereinafter referred to as “transmission audio”). And an upstream attenuator 58 for adjusting the gain of the signal.

In the control circuit 40 configured as described above,
The received audio signal input from the output terminal O first enters the downstream summer 54, inverts and adds the pseudo echo transmitted from the LEC 44, and outputs the inverted signal.
The signal enters the down attenuator 56 via 50, and is output from the down attenuator 56 to the speaker 24 via the volume device 57. In the control circuit 40, the sound collecting microphone 30
Is output after the pseudo echo output from the AEC 46 is inverted and added to the upstream summer 52 and then output to the AGC 48 and further via the upstream attenuator 58. Output to input terminal P.
That is, in the control circuit 40, the AEC 46 is connected to a point X between the volume device 57 and the speaker 24, and receives the received audio signal output from the volume device 57 from this point X, and The amplitude of the impulse response of the echo path, which is the sound transmission path to the sound path 30, and the amplitude of the sound signal output from the speaker 24 and input to the sound collecting microphone 30, are estimated, and based on the estimated impulse response and amplitude. From the received voice signal (voice signal transmitted from the mobile phone to the speaker 24), the sound collecting microphone 30
A pseudo echo corresponding to the voice output from the speaker 24 input to the speaker 24 is generated, and this pseudo echo is added to the transmission voice signal (the voice signal output from the sound collection microphone to the mobile phone) in the opposite phase. That is, the received voice signal is converted by the speaker 24, the voice that has passed through the echo path is collected by the sound collecting microphone 30, and the transmitted voice signal obtained by converting the voice is inverted by the summer 52 using the pseudo echo. Piled up. The AEC 46 is also connected to the central control circuit 42 to input and output control signals and the like from the central control circuit 42. Further, in this control circuit 40, LEC
44 is connected between the upstream attenuator 58 and the input terminal P,
Further, it is connected to the central control circuit 42 in order to input and output control signals and the like from the central control circuit 42.

The central control circuit 42 is connected to the downstream summer 5
4 is connected to a point V between the output terminal O and the above-described navigation processing in the navigation device 1, when the navigation processing is executed, the central control circuit 42 synthesizes using the navigation voice from the voice storage unit 10 shown in FIG. The synthesized speech signal representing the synthesized speech is
From this point V, the signal is output on the receiving channel. further,
The central control circuit 42 includes a downstream summer 54 and a downstream AGC
W point between 50 and the upstream summer 52 and the upstream AGC
Also, the audio signals are detected from the W point and the Y point respectively, and the amplitude of the audio signals output from the AGCs 48 and 50 is set to a predetermined amplitude.
The gain according to the audio signal input to the AGCs 48 and 50 is calculated.

The central control circuit 42 has an AGC 48,5.
The audio signals output from 0 to the receiving channel and the transmitting channel are controlled by the loop attenuator 56 and 58 by a loop gain control process described later to perform necessary attenuation of the audio signal transmitted on each channel.

The LEC 44 differs from the AEC 46 only in that the LEC 44 is used to cancel the transmitted voice signal that is partially reflected by the other party in the transmitted voice signal transmitted from the transmission channel to the interface. The method of generating a pseudo echo for canceling an audio signal is AE
Since it is substantially the same as C46, its description is omitted.

Next, the half loop gain calculated by the central control circuit 42 will be described. The half-loop gain refers to the adjusted components (AGC 48, 50, VOL 57, AEC 46, attenuators 56, 58) of the individual gain adjustments present in the line through which the signal from the reception channel to the transmission channel passes. It is obtained from a gain value or the like.

In this embodiment, the central control circuit 42 determines the gain when the received audio signal passes through the downstream AGC 50 and the volume control unit 57 provided on the reception channel, as the reception gain, and the constant of the pseudo echo estimated by the AEC 46. Ie, echo path gain, uplink AGC provided on the transmission channel
The gain at the time when the transmission audio signal passes is designated as transmission gain 48, and a half loop gain is calculated from these three gains. When an audio signal is transmitted through a transmission line of a reception channel or a transmission channel, the audio signal is attenuated. In this embodiment, a predetermined value is used for the attenuation gain. The calculation formula of the loop gain is expressed by the following formula 1.

[0030]

(Equation 1)

Here, AGC1 is the gain of the downstream AGC 50, VOL is the gain of the volume controller 57, ECO is the echo path gain, AGC2 is the gain of the upstream AGC 48, CHAN
1 is the transmission line of the receiving channel and the gain of the attenuator 56, CH
AN2 represents the transmission line of the transmission channel and the gain of the attenuator 58.

Next, the loop gain control processing will be described. Here, FIG. 3 is a flowchart of the loop gain control process. This loop gain control processing is performed before the mobile phone functions, that is, before receiving an audio signal via the mobile phone.

First, a synthesized voice related to the navigation function is generated in the central control circuit 42, and the process stands by until the synthesized voice is output to the receiving channel (S10). When the synthesized voice signal representing the synthesized voice is output to the reception channel as the received voice signal (S10: YES), the reception gain is calculated (S12). Subsequently, the synthesized voice is output from the speaker 24, passes through the echo path, is collected by the sound collecting microphone 30, and the collected voice is output as a transmission voice signal on the transmission channel. A signal obtained by inverting the pseudo echo is superimposed. When the pseudo echo is generated, the gain obtained from the impulse response of the echo path estimated and the amplitude of the sound transmitted through the echo path is calculated as the echo path gain (S14). Then, when the transmission voice signal passes through the AGC 48 on the transmission channel, the transmission gain is calculated (S16), and a half loop gain is calculated from these three gains (S18).

Next, in this processing, it is determined whether or not the half loop gain is smaller than 1 (S20).
If a negative determination is made in 20) (S20: NO), the attenuator 5
The half loop gain is adjusted to be equal to or less than 1 using 6, 58 (S22), and the process of S10 is performed again. On the other hand, if it is determined that the half loop gain is smaller than 1 (S20:
YES), the half loop gain value is stored, and S
Return to 10. Next, it is determined whether or not the difference between the half loop gain value at the time of the YES determination in S20 and the previously stored half loop gain value has become a certain value or less (for example, 0.01 or less) (S24). Then, in S24, this process is repeated until the half loop gain value becomes equal to or less than the predetermined value. S2
If YES is determined in step 4, this process is terminated, and the finally obtained half loop gain value and the obtained reception gain, echo path gain, and transmission gain (preferably, gain for each function) are controlled by the control circuit. The data is stored in the RAM in 40.

Then, when a signal is received from the mobile phone, each function is performed by using these stored gains.
Perform signal processing. In the present invention, problems such as howling and echo can be substantially suppressed even if S24 in FIG. 3 is omitted.

Using the navigation device 1 described above has the following effects. First, using the navigation device 1 of the present embodiment, before using the mobile phone,
The half-loop gain is controlled to 1 or less using the synthesized voice, and the optimum gain is obtained for each function. Therefore, when using a mobile phone, at least acoustic echo does not occur. From the start, comfortable communication can be performed without the influence of acoustic echo.

When the navigation device 1 of the present embodiment is used, since a half-loop gain has already been calculated when a mobile phone is used, the burden of information processing on the device 1 while the mobile phone is being used. Can be reduced. In this embodiment, the navigation device 1 having the hands-free function has been described.
The present invention is not limited to this, and any device other than a mobile phone that outputs sounds (radio, CD (compact disc), cassette, etc.) may be used as long as it has a hands-free function.

In this embodiment, the half-loop gain is calculated using the synthesized voice. However, the voice input to the navigation device 1 (for example, radio voice, voice recorded on a CD, voice recorded on a cassette tape, etc.). Any voice may be used.

After the affirmative determination in S24, the processing from S12 to S22 of the loop gain calculation processing is performed at predetermined time intervals, and as a result of this processing, the half loop gain calculated immediately before is obtained. Otherwise, the loop gain control process may be performed again. This is because a half-loop gain corresponding to a variable physical distance between the speaker 24 and the sound collecting microphone 30 (ie, the gain of the echo path) immediately before using the mobile phone can always be calculated. .

In this embodiment, the speaker 24 is used as the signal conversion means of the present invention, the sound collecting microphone 30 is used as the voice conversion means, the interface is used as the portable telephone connection means, and the downstream AGC 50 and the volume device 57 are used as the first transmission means. AGC 48 corresponds to the second transmitting means, and the loop gain control processing corresponds to the loop gain control means.

The voice storage unit 10 and the central control circuit 4
The process for generating the synthesized voice in 2 and the output line for outputting the synthesized voice from the central control circuit to the receiving channel correspond to the internal voice output means of the present invention. Further, in the loop gain control processing (S1), S10 to S22
The internal processing of the advance control means of the present invention and the central control circuit 44 for controlling the advance control means corresponds to the gain advance control means.

[Brief description of the drawings]

FIG. 1 is a block diagram of an entire navigation device according to the present embodiment.

FIG. 2 is a circuit diagram of a part of the navigation device according to the embodiment.

FIG. 3 is a flowchart of a loop gain process.

FIG. 4 is a circuit diagram of a part of a conventional navigation device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Navigation apparatus, 10 ... Voice storage part, 12 ... Position detector, 12a ... GPS receiver, 12b ... Gyroscope, 12c ... Distance sensor, 12d ... Geomagnetic sensor,
14: Map data input device, 16: Operation switch group, 18
... external information input device, 20 ... external memory, 22 ... display device, 24 ... speaker, 26 ... remote control sensor, 28 ... interface, 30 ... sound collecting microphone, 40 ... control circuit,
42: Central control circuit, 44: Line echo canceller,
46 ... Acoustic echo canceller, 48 ... Up auto gain control, 50 ... Down auto gain control,
52 ... Up summer, 54 ... Down summer, 56 ... Down attenuator, 57 ... Volume unit, 58 ... Up attenuator

Continuation of the front page F term (reference) 5D020 CC00 CC06 5K027 AA11 BB03 DD08 DD10 DD11 DD14 HH03 5K046 DD13 HH11

Claims (5)

[Claims] An audio signal transmission / reception via a mobile phone is performed by using a separately arranged speaker electrically connected to the mobile phone and a sound collecting microphone that can be arranged by arbitrarily changing a distance between the speaker and the speaker. In a voice communication device having a hands-free function that enables transmission and reception of the voice signal, a voice transmission path from the mobile phone to the mobile phone again via the speaker and the sound collecting microphone is provided. A loop gain control means for controlling a half loop gain of the entire transmission path to 1 or less; and inputting an arbitrary audio signal to the transmission path before receiving an audio signal via the mobile phone; The gain control means sets the half loop gain of the entire transmission path to 1
And a gain advance control means for controlling the following: when an audio signal is received via the mobile phone,
A voice communication device for processing the voice signal based on the half-loop gain controlled as follows. 2. The gain advance control means controls the loop gain control means until the difference between the half loop gains becomes less than or equal to a predetermined value before and after the control of the half loop gain to 1 or less. And when receiving an audio signal via the mobile phone, an audio signal via the mobile phone based on the half-loop gain controlled last by the gain advance control means. The voice communication device according to claim 1, wherein the voice communication device performs the following processing. 3. The voice communication device according to claim 1, wherein the speaker is used in common with a speaker used for a navigation device. 4. A signal conversion means for converting an audio signal into a sound, and an arrangement distance to the signal conversion means can be freely changed;
A voice conversion means for collecting external voices emitted from a distant place and converting the external voices into voice signals; and a mobile phone connected to the mobile phone and receiving the voice from the outside via a wireless line with the mobile phone. A mobile phone connection means for inputting a voice signal from the mobile phone and outputting a transmission voice signal transmitted from the mobile phone to the outside via a wireless line to the mobile phone; and the reception input from the mobile phone connection means A first transmission unit that is provided on a reception channel that transmits an audio signal to the signal conversion unit, and that adjusts and transmits the amplitude of the input reception audio signal under a predetermined condition, and that is output from the audio conversion unit. A second transmission unit provided on a transmission channel for transmitting the transmission audio signal to the mobile phone connection unit, and adjusting and transmitting an amplitude of the input transmission audio signal under a predetermined condition; An attenuator provided on at least one of the reception channel and the transmission channel and capable of attenuating the amplitude of the reception voice signal or the transmission voice signal; and the signal conversion unit converts the reception voice signal and outputs the converted signal. Sound is input to the voice conversion means via an echo path, which is a transmission path of the voice from the signal conversion means to the voice conversion means, and the acoustic echo generated by being re-converted into the transmission voice signal, Estimating the impulse response of an echo path and the amplitude of the reconverted voice, and inverting and adding a pseudo echo generated based on the estimation result to the reconverted transmission voice signal to be transmitted on the transmission channel. When the acoustic echo canceller cancels the acoustic echo and the received audio signal passes through the receiving channel, The reception gain of the first
Detecting from the transmitting means, detecting from the second transmitting means the transmission gain when the transmission audio signal passes through the transmission channel, detecting from the acoustic echo canceller the echo path gain when the voice passes through the echo path. Calculating a half-loop gain of a half-loop including the reception channel, the transmission channel, and the echo path from the reception gain, the transmission gain, and the echo path gain, and operating the attenuator to reduce the half-loop gain to 1 or less. Loop gain control means for controlling the voice conversion means and by using the voice conversion means and the signal conversion means, by converting voice input and output from the mobile phone,
In a voice communication device having a hands-free function capable of transmitting and receiving via the mobile phone without holding the mobile phone, a voice signal other than the received voice signal is transmitted through the reception channel. Using an audio output means for outputting to the conversion means, and the audio signal output from the audio output means,
A voice communication device, comprising: a preceding control unit that precedes the half loop gain calculated by the loop gain control unit to 1 or less before a call via the mobile phone is started. 5. The voice communication device according to claim 4, wherein at least the signal conversion means is used in common with a speaker used in a navigation device.