JP2019198110A - Sound volume control device - Google Patents

Abstract

To provide a sound volume control device capable of correcting, at the same time, a peak of frequency characteristics at two front and rear seats inside a vehicle without need for complex calculation.SOLUTION: A sound volume control device is connected to an output unit arranged between a front seat and a rear seat of a movable body. The sound volume control device estimates a frequency of a peak, common to the frequency characteristics at the front seat and the rear seat, of sound outputted from the output unit, and corrects level of the sound outputted from the output unit at the frequency of the peak. Thus, a sound signal is controlled to correct the peak commonly occurring on the frequency characteristics at two front and rear listening positions.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a technique for adjusting a sound heard by a listener in a passenger compartment space.

  A method for adjusting the sound pressure level of reproduced sound in an acoustic space such as a passenger compartment has been proposed. For example, Patent Document 1 describes a technique of collecting sound radiated from a plurality of speakers with a plurality of microphones, measuring a sound pressure distribution in an acoustic space, and determining a filter coefficient. In this document, a vehicle interior structure is not considered as a phase correction method, and a frequency band to which an equalizer is to be applied is found by simulation and calculation for extracting a peak dip based on frequency characteristics.

JP 2009-159385 A

  When an audio signal is reproduced in the passenger compartment, peaks and dips occur in the frequency characteristics of the audio signal heard in each seat due to reflection from the door, window, seat, etc. of the passenger compartment. Usually, there are a front seat and a rear seat in the vehicle interior, so it is desirable to correct the peak and dip of the frequency characteristics in both seats.

  For example, assume that the sound in a specific band of the rear speaker is too loud for a person in the back seat. In this case, if the sound in that band is reduced, it will be just right for the person in the back seat, but it will be difficult for the person in the front seat to hear the sound in that band. In such a case, it is necessary to perform a large-scale calculation every time in Patent Document 1.

  Examples of the problems to be solved by the present invention include those described above. It is an object of the present invention to provide a volume control device that does not require complicated calculation and can simultaneously correct the peak of frequency characteristics at two front and rear seats in a vehicle.

  The invention according to claim 1 is a volume control device connected to an output unit that outputs sound to a front seat and a rear seat of a moving body, wherein the front seat and the sound output from the output unit An estimation unit that estimates a peak frequency common to the frequency characteristics of the rear seat; and a correction unit that corrects a level of the sound output from the output unit at the peak frequency.

It is a top view which shows the example of the vehicle interior structure of a general sedan vehicle. The schematic structure of the volume control apparatus by an Example is shown. It is a figure explaining the reason where the zone where sound pressure becomes high exists in two front and back seats. It is a figure explaining the method of determining a control zone | band based on the structure of a vehicle. It is a graph which shows the example of the zone | band where sound pressure becomes high with two front and back. It is a graph which shows the effect of the technique of a prior art, and the technique of an Example. The structure of the volume control apparatus which reproduces | regenerates an audio | voice from a left and right speaker is shown. Frequency characteristics when stereo signals are input to the left and right speakers are shown.

Frequency characteristics when monaural signals are input to the left and right speakers are shown. It is a flowchart of the attenuation | damping control by the volume control apparatus of an Example. The example of the in-vehicle environment in a modification is shown.

  In a preferred embodiment of the present invention, the volume control device connected to the output unit disposed between the front seat and the rear seat of the moving body is configured to transmit the sound output from the output unit to the front seat and the An estimation unit that estimates a peak frequency common to frequency characteristics in the rear seat, and a correction unit that corrects a level of the sound output from the output unit at the peak frequency.

  Said volume control apparatus is connected to the output part arrange | positioned between the front seat and rear seat of a moving body. The volume control device estimates a peak frequency common to the frequency characteristics of the front seat and the rear seat of the sound output from the output unit, and corrects the level at the peak frequency of the sound output from the output unit. As a result, the audio signal is controlled so as to correct peaks that appear in common in the frequency characteristics at the two listening positions of the front seat and the rear seat.

  In one aspect of the volume control device, the peak is output from the output unit, and is output from the output unit and a direct sound that is a sound that reaches the listening position without being reflected in the moving body, and the movement It is generated by superimposing each of the reflected sound that is the sound that has been reflected at a predetermined position in the body and then reaches the listening position. In this aspect, correction is performed on a peak generated by superimposing the direct sound and the reflected sound.

  In another aspect of the volume control device, the estimation unit estimates the peak frequency based on vehicle information of the moving body. In this aspect, the peak frequency is determined based on the vehicle information of the moving body.

  Another aspect of the sound volume control device includes an input unit that inputs vehicle information of the moving body, and the estimation unit estimates the frequency of the peak based on the input vehicle information. In this aspect, the peak frequency is estimated based on the vehicle information input by the user. In a preferred example, the estimation unit estimates the peak frequency by a calculation formula based on a vehicle width of the moving body.

  In another aspect of the volume control device, the output unit is disposed at a position near the front seat or the rear seat. Since the output unit is arranged near the front seat or the rear seat, a peak common to the frequency characteristics of the front seat and the rear seat occurs.

  In another aspect of the above-described volume control device, the front seat or the rear seat has a shielding object, and the shielding object is output from the output unit and the shielding object is out of the front seat or the rear seat. There is a partial blockage in the sound that reaches the listening position of the existing seat. A peak common to the frequency characteristics of the front seat and the rear seat occurs due to the shielding of the front seat or the rear seat.

  In another preferred embodiment of the present invention, the volume control method executed by the volume control device connected to the output unit disposed between the front seat and the rear seat of the moving body is output from the output unit. An estimation step of estimating a peak frequency common to the frequency characteristics of the front seat and the rear seat, and a correction step of correcting a level of the voice output from the output unit at the peak frequency. Have. This method also controls the audio signal so as to correct peaks that appear in common in the frequency characteristics at the two listening positions of the front seat and the rear seat.

  In another preferred embodiment of the present invention, a program executed by a volume control device that includes a computer and is connected to an output unit disposed between a front seat and a rear seat of a moving body is output from the output unit. As an estimation unit that estimates the peak frequency common to the frequency characteristics of the front seat and the rear seat of the output sound, and a correction unit that corrects the level at the peak frequency of the sound output from the output unit, Make the computer function. By executing this program on a computer, the audio signal is controlled so as to correct peaks that appear in common in the frequency characteristics at the two listening positions of the front seat and the rear seat. This program can be stored in a storage medium and handled.

[Basic principle]
First, the basic principle of volume control according to the embodiment will be described. Although the acoustic characteristics in the passenger compartment depend on the vehicle interior structure, a typical vehicle has a similar vehicle interior structure and speaker position. In a normal sedan vehicle or the like, a driver seat and a passenger seat are arranged symmetrically in the front seat, and two seats are arranged symmetrically in the rear seat. A front speaker and a rear speaker are installed on the left and right doors, respectively. As described above, in a general vehicle, the vehicle interior structure and the speaker position are similar, and thus the way in which sound is transmitted from the left and right rear speakers to the front seat and the rear seat is basically similar in any vehicle.

  FIG. 1 shows an example of the interior structure of a general sedan vehicle. If the vehicle 1 is a right-hand drive vehicle, the driver 5 sits in the front seat (driver's seat) 2f, and the passenger 6 sits in the rear seat 2r. A left rear speaker RL is provided on the left door of the rear seat. A right rear speaker RR is provided on the right door of the rear seat, but is not shown in FIG.

  In such an in-vehicle structure and speaker position, if the two front and rear seats of the vehicle, that is, the front seat 2f and the rear seat 2r are listening positions, the sound reproduced from one rear speaker is listened to at these two seats. There is a frequency band (hereinafter, also simply referred to as “band”) in which a peak appears in the frequency characteristics of the sound heard at the seat. This is a sound that directly reaches the listening position from the rear speaker provided on the door (hereinafter referred to as “direct sound”), is reproduced from the rear speaker, is reflected by the door on the opposite side, and reaches the listening position. This is because the sound to be played (hereinafter referred to as “reflected sound”) is superimposed (added) at the listening position of the two seats.

  The “listening position” is the head position of the passenger sitting in the front seat or the rear seat, and the “sound pressure at the listening position” is the sound pressure at the center position of the passenger's head or the passenger's head position. The sum of the sound pressures at the left and right ear positions. In addition, in the following description, “two seats” refers to two front and rear seats, specifically, a front seat and a rear seat on the right side of the passenger compartment, or a combination of a front seat and a rear seat on the left side. To do.

  As described above, in the sound volume control device according to the present embodiment, the frequency band of the audio signal listened at the two seats of the vehicle has a peak (hereinafter also referred to as “common peak band”) as the control band, and the control is performed. In the band, the frequency characteristics at the two seats are simultaneously corrected by performing attenuation control of the audio signal reproduced from the rear speaker.

[Example]
(Basic configuration)
FIG. 2 shows a schematic configuration of the volume control device 10 according to the embodiment. In this embodiment, when outputting sound from at least one speaker to two seats of the vehicle, attenuation control is performed in a specific control band of the sound signal supplied to the speaker. This attenuation control includes equalizer processing, gain adjustment processing, attenuation processing, and the like.

  Specifically, as shown in the example of FIG. 2, the audio signal output from the sound source 11 is supplied to the equalizer 12. The equalizer 12 performs control to attenuate the level of the audio signal in the control band, and supplies the attenuated audio signal to the rear speaker RL provided in the vehicle 1. The rear speaker RL reproduces the supplied audio signal and outputs audio.

  A control unit 15 is connected to the equalizer 12, and an input unit 16 is connected to the control unit 15. The input unit 16 is used when the user inputs vehicle information such as a vehicle type name as will be described later. The control unit 13 supplies a signal indicating the control band to the equalizer 12 based on the vehicle information input to the input unit 16. Specifically, the control unit 15 stores a vehicle information database (DB) in which vehicle information such as a vehicle type name is associated with the vehicle width of the vehicle type. When the user inputs a vehicle type name to the input unit 16, the control unit 15 refers to the vehicle information DB, acquires the vehicle width (w) of the vehicle type, and determines the control band as described later using the vehicle width. To do.

  Thereby, in the volume control apparatus of the present embodiment, it is possible to correct the peak appearing in the frequency characteristics of the sound heard at the two seats without performing complicated calculation. In the above example, the sound is output only from the left rear speaker RL of the vehicle, but the present invention can be similarly applied to the case where the sound is output only from the right rear speaker RR.

(Determine control bandwidth)
First, the reason why there is a common peak band in which the sound pressures of audio signals heard at two seats of the vehicle simultaneously increase will be described. 3 (A) and 3 (B) schematically show the situation inside the vehicle when a passenger is in two seats. As shown in FIG. 3A, the sound output from the rear speaker RL is likely to be transmitted only to the rear seat (hereinafter referred to as “phenomenon 1”). This is a structure in which the back of the front seat, in particular, the back of the front seat shields the space of the front seat and the space of the rear seat, and the sound output from the rear speaker RL is partially blocked by the back seat. This is because it is difficult to communicate.

  On the other hand, as shown in FIG. 3B, the front seat is closer to the front seat than the rear seat in the front direction of the rear speaker RL, that is, the direction in which the sound output from the rear speaker RL travels (FIG. 3B ) Circle 7). Therefore, the direct sound and the reflected sound output from the rear speaker RL are more likely to overlap, that is, interfere with each other in the front seat than the rear seat (hereinafter referred to as “phenomenon 2”). Due to the above phenomenon 1 and phenomenon 2, a common peak band in which the sound pressure of the audio signal simultaneously increases at the two front and rear seats.

  Note that the degree of the above phenomenon 2 depends on the position of the rear speaker RL in the front-rear direction, but in a general vehicle, as shown in FIG. Is often arranged closer to the front seat than the middle position between the front seat and the rear seat, the phenomenon 2 described above occurs.

  Next, a method for determining the frequency of the common peak band (hereinafter also referred to as “common peak frequency”) will be described. FIG. 4 shows an example of a vehicle interior structure. As shown in the path S, the sound output from the rear speaker RL reaches the front seat 2f and the rear seat 2r as a direct sound, is reflected by the right door, and is reflected as a reflected sound to the front seat 2f and the rear seat 2r. To reach. Thus, since the direct sound and the reflected sound reach the front seat 2f and the rear seat 2r as the listening position, the direct sound and the reflected sound are added in the band where the direct sound and the reflected sound are in phase. Peak occurs in the frequency characteristics. The frequency at which this peak occurs is the common peak frequency.

The common peak frequency can be determined based on the size of the vehicle. As shown in FIG. 4, when the vehicle width in the vehicle is “w”, the common peak frequency Fpeak is
Fpeak [Hz] = C [m / s] / D [m] (1)
It is obtained by. Note that “C” is the speed of sound (340 ms), and D (= 2w) is the distance until the sound output from the rear speaker RL is reflected by the opposite door and returns to the position of the rear speaker, that is, , The distance of the route S shown in FIG.

  Assuming that the width of a general vehicle is w = 1.4 m, the common peak frequency Fpeak is about 121 Hz from the equation (1). FIG. 5A shows frequency characteristics in the front seat (driver's seat) and the rear seat in this case. As indicated by an ellipse 70, a peak common to the front seat and the rear seat occurs in a band near 125 Hz.

(Attenuation control)
Thus, when the common peak frequency as the control band is determined, the control unit 15 controls the equalizer 12 to attenuate the signal level in the band of the common peak frequency. Specifically, as illustrated in FIG. 5B, the control unit 15 sets a characteristic for attenuating the signal level near the common peak frequency in the equalizer 12. As a result, it is possible to correct peaks that occur simultaneously in the two front and rear seats due to the vehicle interior structure.

  FIG. 6 shows a graph comparing an example in which the above attenuation control is performed with a conventional example. The graph G1 shows the frequency characteristic of the front seat according to the example, and the graph G2 shows the frequency characteristic of the rear seat according to the example. Graph G3 shows the frequency characteristic of the front seat according to the conventional example, and graph G4 shows the frequency characteristic of the rear seat according to the conventional example. Note that the graphs G3 and G4 of the conventional example are graphs when the band of the peak frequency (about 300 Hz) generated in the frequency characteristics in the rear seat is attenuated by the equalizer. In each graph, a solid line indicates a characteristic when the attenuation process by the equalizer is turned off, and a broken line indicates a characteristic when the attenuation process by the equalizer 12 is turned on. In any graph, the listening position is the position of the left ear of the passenger's head.

  In the conventional example, as shown by the solid line in the ellipse 74 of the graph G4, a peak occurs in the frequency characteristic of the rear seat in a band near 300 Hz. For this reason, when the equalizer that attenuates the band near 300 Hz is turned on, the frequency characteristic of the rear seat becomes flat in the band near 300 H, as indicated by the broken line in the ellipse 74. However, as shown by the solid line in the ellipse 73 of the graph G3, since no peak originally exists in the vicinity of 300 Hz in the front seat, when the equalizer that attenuates the band near 300 Hz is turned on, as shown by the broken line in the ellipse 73 In the front seat, a dip occurs in the vicinity of 300 Hz, and the frequency characteristics deteriorate.

  On the other hand, in the embodiment, as shown by the solid line in the ellipse 71 of the graph G1 and the solid line in the ellipse 72 of the graph G2, there are peaks in both the front seat and the rear seat near 125 Hz corresponding to the common peak frequency. Arise. Therefore, when the equalizer that attenuates the band near 125 Hz is turned on, as shown by the broken line in the ellipse 71 of the graph G1 and the broken line in the ellipse 72 of the graph G2, the peaks are alleviated and the frequency is reduced. The characteristics are improved. As described above, in this embodiment, the frequency characteristics in both the front and rear two seats can be improved simultaneously by attenuating the band of the common peak frequency that causes the peaks in both the front and rear two seats at the same time.

[Other embodiments]
In the above embodiment, sound is output from only one of the rear speakers of the vehicle, but the present invention can also be applied to a case where sound is output from the left and right rear speakers. FIG. 7 shows a configuration in which signals are input to the left and right rear speakers RL and RR. Specifically, the audio signal output from the sound source 11 is input to the equalizer 12, and the equalizer 12 supplies the audio signal with the attenuated control band level to the left and right rear speakers RL, RR.

  In a general vehicle interior structure, left and right rear speakers RL and RR are installed at symmetrical positions. Accordingly, the sound output from the right rear speaker RR also reaches the front seat 2f and the rear seat 2r as direct sounds, and reaches the front seat 2f and the rear seat 2r as reflected sounds reflected by the left door. For this reason, even when sound is output from the left and right speakers RL, RR, the common peak in the frequency characteristics of the front seat 2f and the rear seat 2r is simultaneously suppressed by attenuating the volume level of the control band by one equalizer 12. be able to. Hereinafter, a case of a stereo signal and a monaural signal will be described.

(Stereo signal)
In the case of a stereo signal, an uncorrelated signal is input to the left and right rear speakers RL and RR, but in either of the two front and rear seats, the direct sound from the left and right rear speakers RL and RR and the door on the opposite side Since the reflected sound that has been reflected forms a peak frequency, the peak frequencies for the sounds output from the left and right rear speakers RL and RR are the same. Therefore, if attenuation control is performed in the peak frequency band by one equalizer, the peaks of the sound output from the two rear speakers RL and RR can be suppressed simultaneously.

  FIG. 8 shows frequency characteristics when stereo signals are input to the left and right rear speakers RL and RR in the configuration of FIG. FIG. 8A shows frequency characteristics of the front seat (driver's seat) 2f and the rear seat 2r. As indicated by an ellipse 75, a common peak appears in the vicinity of 125 Hz. Therefore, the common peak frequency of 125 Hz is set as the center frequency of the control band, and the attenuation characteristics shown in FIG. Thereby, the frequency characteristics shown in FIG. 8C are obtained in the front seat 2f and the rear seat 2r. As shown by an ellipse 76 in FIG. 8C, a common peak near 125 Hz is suppressed.

(In the case of monaural signal)
In the case of a monaural signal, the same signal is input to the left and right speakers FL and FR. Therefore, even when a monaural signal is input to the left and right rear speakers RL and RR, as in the case where a signal is input to only one speaker, if attenuation control is performed in the peak frequency band with one equalizer, The peak of the sound output from the speakers RL and RR can be suppressed at the same time.

  FIG. 9 shows frequency characteristics when a monaural signal, that is, the same signal is input to the left and right front speakers FL and FR in the configuration of FIG. FIG. 9A shows the frequency characteristics of the front seat (driver's seat) 2f and the rear seat 2r. As indicated by an ellipse 77, a common peak appears around 125 Hz. Therefore, the peak frequency of 125 Hz is set as the center frequency of the control band, and the attenuation characteristic shown in FIG. As a result, the frequency characteristics shown in FIG. 9C are obtained in the front seat 2f and the rear seat 2r. As shown by an ellipse 78 in FIG. 9C, a common peak near 125 Hz is suppressed.

  As described above, by applying the same attenuation processing to the audio signals output from the left and right rear speakers RL and RR, a common peak generated in the front and rear two seats, that is, the front passenger seat and the rear seat, is obtained. It can also be suppressed. As a result, it is possible to obtain the effect of simultaneously suppressing the common peak for the four seats in the vehicle.

[Attenuation control]
FIG. 10 is a flowchart of the attenuation control executed by the volume control device 10 of the embodiment. This process is mainly executed by the control unit 15 of the volume control device 10. Specifically, it is implemented by executing a program prepared in advance by a computer constituting the control unit 15.

  First, when the user inputs vehicle information such as a vehicle type name to the input unit 16, the control unit 15 acquires the input vehicle information (step S11), and acquires the vehicle width of the vehicle type from the vehicle information DB (step S12). ). Next, the control unit 15 determines the common peak frequency Fpeak based on the above-described formula (1) (step S13), and sets the characteristic for attenuating the signal in the common peak band in the equalizer 12 (step S14). Then, the control unit 15 controls the sound source 11 to output an audio signal. Thus, the sound output from the rear speaker has a common peak suppressed.

[Modification]
In the above-described embodiment, the rear speaker RL is close to the front seat, and the backrest of the front seat serves as a shield that shields the front seat space and the rear seat space. Instead, the present invention can also be applied in an in-vehicle environment where the rear speaker RL is close to the rear seat and there is a shield on the rear seat. FIG. 11 shows an example of an in-vehicle environment having a shield on the rear seat. In the example of FIG. 11, the rear speaker RL is close to the rear seat. The front seat 2f faces the rear of the vehicle and faces the rear seat 2r. In place of the backrest of the front seat in the above embodiment, the shielding object X exists between the front seat 2f and the rear seat 2r. Examples of the shielding object X include a partition, a large screen television, a desk, and the like. Even in this in-vehicle environment, the sound output from the rear speaker RL is partially blocked by the shielding object X and is not easily transmitted to the rear seat. In this way, the present invention can be applied in an in-vehicle environment where the rear speaker is close to either the front seat or the rear seat, and there is a shield on the close seat.

  In the above embodiment, the signal in the common peak band is attenuated by the equalizer 12, but as an actual process, only the signal in the common peak band is attenuated and the signal level in the other band is maintained. In addition, while maintaining the signal level of the common peak band, the signal level of the other band may be increased to relatively attenuate the signal of the common peak band.

  As the vehicle width acquired by the control unit 15 when determining the common peak frequency, that is, the vehicle width stored in the vehicle information DB, it is optimal to use the width of the interior of the passenger compartment. However, when it is difficult to obtain the width of the interior, the width of the exterior described in a vehicle catalog or the like may be used instead. Further, a value obtained by subtracting a value corresponding to a general door thickness from the width of the exterior may be stored in the vehicle information DB.

  In the above embodiment, the vehicle information DB is prepared in the control unit 15 mounted on the vehicle. Instead, the vehicle information DB is prepared in a server or the like, and the control unit 15 mounted on the vehicle communicates. It is good also as acquiring a vehicle width from a server by. Specifically, the control unit 15 may transmit vehicle information such as the vehicle type name input to the input unit 16 to the server, and use the vehicle width of the vehicle type received from the server.

1 Vehicle 2f Front seat (driver's seat)
2r Rear seat 10 Volume control device 11 Sound source 12 Equalizer 15 Control unit 16 Input unit

Claims (1)

A volume control device connected to an output unit that outputs sound to a front seat and a rear seat of a moving body,
An estimation unit that estimates a frequency of a peak common to frequency characteristics in the front seat and the rear seat of the sound output from the output unit;
A correction unit that corrects a level at the peak frequency of the sound output from the output unit;
A volume control apparatus comprising:

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