JP2010124283A - Sound image localization control apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound image localization control apparatus controlling a sound image localization position of a center component without being influenced by a reflected wave or a shielding in a vehicle room while holding a sound quality and a feeling of presence. <P>SOLUTION: A band division means 2 extracts an audio signal of an intermediate frequency component and a monaural component extraction means extracts only an audio signal of a monaural component in the intermediate frequency component to perform weighting corresponding to a right and left balance amount by a right and left weight addition means and to perform weighting corresponding to a front and rear fader amount by a front and rear weight addition means. Thereby, weighting processing corresponding to a front-and-rear direction or a right-and-left direction is applied only to the monaural component which has a reduced influence on the sound quality or feeling of existence in the audio signal of the intermediate frequency band in which much vocal sound is included, so that a localization position of a sound image is effectively controlled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sound image localization control device, and more specifically, by adjusting the balance of a center component (monaural component) in an audio signal of a mid-frequency component and adjusting a fader, the mid-frequency component including a lot of vocal components. The present invention relates to a sound image localization control device capable of performing localization control on a sound image.

  In general in-vehicle audio, for example, a balance function that adjusts the volume of the left and right speakers and a fader function that adjusts the volume of the front and rear speakers are often used as a method of localizing the sound image output from the speakers. (For example, refer to Patent Document 1). There are also vehicles equipped with a seat position function (time alignment adjustment function) that performs localization control of a sound image by adjusting a time difference until sound output from a speaker reaches a predetermined position.

Thus, the localization position of the sound image can be adjusted by using a balance function for the left and right speakers, a fader function for the front and rear speakers, and the like.
JP 2000-197182 A (page 6, FIG. 8)

  However, if the localization position of the sound image is adjusted using the balance function or the fader function, the level balance of the sound volume for each speaker is changed, so that there is a problem that the sound quality and the sense of reality change greatly.

  In addition, even when adjustment is performed using the seat position function, the level of reflected waves tends to increase in the passenger compartment, and furthermore, there are many effects of shielding by the seat back, etc. However, it is difficult to adjust the sound arrival time over the entire frequency band, and it is not easy to sufficiently adjust the sound image localization position.

  The present invention has been made in view of the above problems, and can control the localization position of a sound image without being affected by reflected waves or shielding in the passenger compartment while maintaining sound quality and presence. It is an object to provide a sound image localization control device.

  In order to solve the above problems, a sound image localization control device according to the present invention provides a sound image for an audio signal of a stereo sound source output to the right speaker and the left speaker in a vehicle interior having at least a right speaker and a left speaker. A sound image localization control apparatus for performing localization control processing of the stereo sound source, comprising: balance setting means for setting localization in the left-right direction of the audio signal; Based on band dividing means for dividing a frequency component into a middle frequency component, and an audio signal having a middle frequency component in the left channel and an audio signal having a middle frequency component in the right channel divided by the band dividing means. Monaural components with common signal characteristics Different signal based on the mono component extracting means for extracting the audio signal of the audio signal, and the audio signal of the mid-frequency component in the left channel and the audio signal of the mid-frequency component in the right channel divided by the band dividing means Stereo component extraction means for extracting a stereo component audio signal having characteristics, and the left and right balance amounts set by the balance setting means for the monaural component audio signal extracted by the monaural component extraction means Left and right weight addition means for generating a mono component audio signal in the left channel and a mono component audio signal in the right channel by adding weights, and the left side to which the weight is added by the left and right weight addition means By combining the audio signal of the mono component in the channel and the audio signal of the mono component in the right channel with the audio signal of the stereo component extracted by the stereo component extracting means, A middle frequency component synthesizing unit that generates an audio signal of a band frequency component and an audio signal of a middle frequency component in the left channel; a mid frequency component of the left channel generated by the mid frequency component synthesizing unit; The audio signal and the audio signal of the low frequency band component in the left channel divided by the band dividing means are synthesized, and the audio of the mid frequency component in the right channel generated by the mid frequency component synthesizing means Trust And a band synthesizing unit that synthesizes the audio signal of the low and high frequency components in the right channel band-divided by the band dividing unit.

  According to the sound image localization control device of the present invention, the audio signal of the mid-frequency component is extracted by the band dividing means, and only the audio signal of the monaural component is extracted from the mid-frequency component by the monaural component extracting means. Weighting corresponding to the left and right balance amounts set by the balance setting means is performed by the adding means. For this reason, it is possible to apply a weighting process corresponding to the left and right direction only to a monaural component that has a low influence on sound quality and realism, which is an audio signal in a mid-frequency band that contains a lot of vocal sounds.

  Therefore, the stereo component at the middle frequency is synthesized using the middle frequency component synthesizing means to the monaural component audio signal subjected to the weighting process, and the low and high frequency audio for the left and right channels is synthesized using the band synthesizing means. The audio signal of the stereo sound source generated by synthesizing the signals is adjusted for the mid-frequency components that contain a lot of vocal sounds without controlling the stereo components that affect the sound quality and presence. be able to. For this reason, by using the sound image localization control device according to the present invention, it is possible to effectively perform the localization position control of the sound image in the left-right direction without impairing the sound quality and the presence.

  Also, the sound image localization control device according to the present invention includes a sound image localization control process for an audio signal of a stereo sound source output to the front speaker and the rear speaker in a vehicle interior including at least a front speaker and a rear speaker. A sound image localization control device for performing audio signal localization, a fader setting means for performing localization setting in the front-rear direction of the audio signal, and a low-frequency component in the left channel and the right channel of the stereo sound source audio signal. Based on the band dividing means for dividing the frequency band into the frequency components, the audio signal of the middle frequency component in the left channel and the audio signal of the middle frequency component in the right channel divided by the band dividing means. Mono component audio signal with signal characteristics A stereo component having different signal characteristics based on the output monaural component extraction means and the midband frequency component audio signal in the left channel and the midband frequency component audio signal in the right channel that are band-divided by the band splitting means Stereo component extraction means for extracting component audio signals, and weighting corresponding to the front and rear fader values set by the fader setting means to the monaural component audio signals extracted by the monaural component extraction means The front-side weighting adding means for generating the monaural component audio signal for the front speaker and the monaural component audio signal for the rear speaker, and the front side to which the weighting is added by the front-back weighting adding means Monaural component for speakers The audio signal is divided into the audio signal for the front speaker in the right channel and the left channel, and the monaural component audio signal for the rear speaker is further divided into the audio for the rear speaker in the right channel and the left channel. By dividing the audio signal of the stereo component extracted by the stereo component extracting means with respect to all the divided audio signals, the middle frequency component for the front speaker in the right channel is divided. An audio signal of the middle frequency component for the rear speaker in the right channel, an audio signal of the middle frequency component for the front speaker in the left channel, and the rear speed signal in the left channel; A mid-frequency component synthesizing unit for generating a mid-frequency component audio signal for a speaker; and a mid-frequency component audio signal for the front speaker in the right channel synthesized by the mid-frequency component synthesizing unit And the audio signal of the low frequency band component for the right channel divided by the band dividing means with the audio signal of the mid band frequency component for the rear speaker in the right channel, and The band division is performed on the audio signal of the mid-frequency component for the front speaker in the left channel and the audio signal of the mid-frequency component for the rear speaker in the left channel synthesized by the frequency component synthesizing unit. Low and high frequency components for the left channel Characterized in that it comprises a band synthesizing means for synthesizing the audio signal.

  According to the sound image localization control device according to the present invention, the audio signal of the mid-frequency component is extracted by the band dividing means, and only the audio signal of the monaural component is extracted from the mid-frequency component by the monaural component extracting means, and the front-to-back weighting is performed. The adding unit performs weighting corresponding to the previous and next fader amounts set by the fader setting unit. For this reason, it is possible to perform weighting processing corresponding to the front-rear direction only on a monaural component that has a low influence on sound quality and realism, which is an audio signal in a mid-frequency band that includes a lot of vocal sounds.

  Therefore, the stereo component at the middle frequency is synthesized using the middle frequency component synthesizing means to the monaural component audio signal subjected to the weighting process, and the low and high frequency audio for the left and right channels is synthesized using the band synthesizing means. The audio signal of the stereo sound source generated by synthesizing the signals is adjusted for the mid-frequency components that contain a lot of vocal sounds without controlling the stereo components that affect the sound quality and presence. be able to. For this reason, by using the sound image localization control device according to the present invention, it is possible to effectively perform the localization position control in the front-rear direction of the sound image without impairing the sound quality and the presence.

  Furthermore, the sound image localization control device according to the present invention is a sound image localization for performing a sound image localization control process for an audio signal of a stereo sound source output to each speaker in a vehicle interior having at least four speakers on the front, rear, left and right sides. A control device, comprising: balance setting means for performing left and right direction localization setting in the audio signal; fader setting means for performing front and rear direction localization setting in the audio signal; and left and right audio signals of the stereo sound source Band division means for dividing a band into a low-high frequency component and a middle frequency component in the channel and the right channel, an audio signal of a middle frequency component in the left channel divided by the band division means, and a middle band in the right channel Common based on audio signal of frequency component A monaural component extracting means for extracting a monaural component audio signal having a signal characteristic; an audio signal of a mid-frequency component in the left channel divided by the band dividing means; and an audio signal of a mid-frequency component in the right channel And a stereo component extracting means for extracting a stereo component audio signal having different signal characteristics, and a left and right set by the balance setting means for the monaural component audio signal extracted by the monaural component extracting means. Left and right weighting adding means for generating a monaural component audio signal in the left channel and a mono component audio signal in the right channel by adding a weight corresponding to the balance amount, and the left and right weighting adding means. By adding a weight corresponding to the front and rear fader values set by the fader setting means to the monaural component audio signal in the left channel, the monaural component audio signal for the front speaker in the left channel; and A monaural component audio signal for the rear speaker in the left channel, and the monaural component audio signal in the right channel generated by the left and right weighting adding unit before and after being set by the fader setting unit Before generating a monaural component audio signal for the front speaker in the right channel and a monaural component audio signal for the rear speaker in the right channel by adding a weight corresponding to the amount of fader The stereo component extraction means extracts all the audio signals weighted corresponding to the left and right balance amounts and the front and rear fader amounts by the post weight addition means, the left and right weight addition means and the front and rear weight addition means. By combining the stereo component audio signal, an audio signal of the mid-frequency component for the front speaker in the right channel, and an audio signal of the mid-frequency component for the rear speaker in the right channel, Middle frequency component synthesizing means for generating an audio signal of a mid-frequency component for the front speaker in the left channel and an audio signal of a mid-frequency component for the rear speaker in the left channel; Synthesized by the frequency component synthesis means An audio signal for the right channel that is band-divided by the band dividing unit with respect to the audio signal of the mid-frequency component for the front speaker in the side channel and the audio signal of the mid-frequency component for the rear speaker in the right channel An audio signal having a low and high frequency component is synthesized, and an audio signal having a middle frequency component for the front speaker in the left channel synthesized by the middle frequency component synthesizing unit and for the rear speaker in the left channel Band synthesizing means for synthesizing the audio signal of the low frequency band component for the left channel divided by the band dividing means with respect to the audio signal of the middle frequency component.

  According to the sound image localization control device of the present invention, the audio signal of the mid-frequency component is extracted by the band dividing means, and only the audio signal of the monaural component is extracted from the mid-frequency component by the monaural component extracting means. Weighting corresponding to the left and right balance amount by the adding means and weighting corresponding to the front and rear fader amounts by the front and rear weighting adding means are performed. For this reason, it is possible to perform weighting processing corresponding to the front, rear, left, and right directions only for a monaural component that has a low influence on sound quality and realism, and is an audio signal in a mid-frequency band that includes a lot of vocal sounds. .

  Therefore, the stereo component at the middle frequency is synthesized using the middle frequency component synthesizing means to the monaural component audio signal subjected to the weighting process, and the low and high frequency audio for the left and right channels is synthesized using the band synthesizing means. The audio signal of the stereo sound source generated by synthesizing the signals is adjusted for the mid-frequency components that contain a lot of vocal sounds without controlling the stereo components that affect the sound quality and presence. be able to. For this reason, by using the sound image localization control apparatus according to the present invention, it is possible to effectively perform the localization position control in the front-rear and left-right directions of the sound image without impairing the sound quality and the sense of presence.

  In the sound image localization control device according to the present invention, the band dividing unit extracts the audio signal of the middle frequency component, the monaural component extracting unit extracts only the audio signal of the monaural component from the mid frequency component, and the right and left weighting adding unit The weighting corresponding to the left and right balance amount due to or the weighting corresponding to the front and rear fader amount by the front and rear weighting adding means is performed. For this reason, it is possible to perform weighting processing corresponding to the front-rear direction or the left-right direction only for monaural components that have a lot of vocal sounds and that have less influence on sound quality and realism. It becomes.

  Therefore, the stereo component at the middle frequency is synthesized using the middle frequency component synthesizing means to the monaural component audio signal subjected to the weighting process, and the low and high frequency audio for the left and right channels is synthesized using the band synthesizing means. The audio signal of the stereo sound source generated by synthesizing the signals is adjusted for the mid-frequency components that contain a lot of vocal sounds without controlling the stereo components that affect the sound quality and presence. be able to. For this reason, by using the sound image localization control device according to the present invention, it is possible to effectively perform the localization position control in the front-rear direction or the left-right direction of the sound image without impairing the sound quality or the sense of presence.

  Hereinafter, a sound image localization control device according to the present invention will be described in detail with reference to the drawings. The sound image localization control device is installed in an in-vehicle audio device or a car navigation system, and is operated by a listener using a sound image localization balance setting unit and a sound image localization fader setting unit described below in the vehicle. By doing so, it is possible to adjust the localization position of the sound image.

  FIG. 1 is a block diagram showing a schematic configuration of a sound image localization control device. The sound image localization control device 1 includes a band division unit (band division unit) 2, a localization control unit 3, addition units (band synthesis unit) 4 to 7, a sound image localization balance setting unit (balance setting unit) 8, And a sound image localization fader setting unit (fader setting means) 9.

  The band dividing unit 2 has a role of dividing an input signal into a low and high frequency part obtained by adding a low frequency part and a high frequency part, and a middle frequency part. Note that the sound image localization control apparatus 1 according to the present embodiment will be described on the assumption that two-channel audio signals (the L-side channel audio signal and the R-side channel audio signal) are input.

  FIG. 2 is a block diagram showing a schematic configuration of the band dividing unit 2. As shown in FIG. 2, the band dividing unit 2 includes a first low-pass filter unit 10, a second low-pass filter unit 11, a first high-pass filter unit 12, a second high-pass filter unit 13, an adder unit 14, And a phase inversion unit 15.

  The first low-pass filter unit 10 and the second low-pass filter unit 11 are configured by two-stage cascade connection of low-pass type third-order Butterworth filters. The first high-pass filter unit 12 and the second high-pass filter unit 13 are configured by cascade-connecting high-pass third-order Butterworth filters in two stages.

  FIG. 3 shows a band-by-band filter in which band division is performed in the band dividing unit 2 by using the first low-pass filter unit 10, the second low-pass filter unit 11, the first high-pass filter unit 12, and the second high-pass filter unit 13. The characteristics are shown.

  Here, the cutoff frequency of the first low-pass filter unit 10 is 300 Hz, the cutoff frequency of the second low-pass filter unit 11 is 6,000 Hz, the cutoff frequency of the first high-pass filter unit 12 is 300 Hz, and the second high-pass filter unit. The cutoff frequency of 13 is 6,000 Hz.

  When the first low-pass filter unit 10 is applied to the audio signal of the L-side channel as shown in FIG. 2 using the filter units 10 to 13 having such a cutoff frequency set, the first low-pass filter The audio signal that has passed through the unit 10 becomes an audio signal in a low frequency band of 300 Hz or less, and only a low frequency component (“Low” shown in FIGS. 2 and 3) is extracted. Further, when the first high-pass filter unit 12 is applied to the L-side channel audio signal, the audio signal that has passed through the first high-pass filter unit 12 becomes an audio signal in a high frequency band of 6,000 Hz or higher, Only the frequency component (“High” shown in FIGS. 2 and 3) is extracted.

  Further, when the second low-pass filter unit 11 is applied to the audio signal of the L-side channel, the audio signal that has passed through the second low-pass filter unit 11 is an audio having a middle frequency component + low frequency component of 6,000 Hz or less. When the second high-pass filter unit 13 is applied to the audio signal of the middle frequency component + the low frequency component, the signal passes through the second high-pass filter unit 13 (“Low + Mid” shown in FIG. 2). The audio signal is an audio signal in a high frequency band of 300 Hz or higher. That is, the audio signal that has passed through the second low-pass filter unit 11 and the second high-pass filter unit 13 is an audio signal in the mid-frequency band that is 300 Hz or more and 6,000 Hz or less (“Mid” shown in FIGS. 2 and 3). ) The audio signal in the middle frequency band is generally a signal corresponding to the audio band of the audio signal.

  In this way, by combining the respective filter units 10 to 13, as shown in FIG. 3, the band of the stereo signal of the input L-side channel is reduced to a low frequency component (Low) and a mid frequency component (Mid). It becomes possible to divide into high frequency components (High). In FIG. 2, only the configuration of the band dividing unit 2 in the case where the filter units 10 to 13 are applied only to the audio signal of the L side channel is shown, but also to the audio signal of the R side channel. Similarly, the filter units 10 to 13 are applied to divide the R-side channel stereo signal band into a low-frequency component (Low), a mid-frequency component (Mid), and a high-frequency component (High).

  In the adding unit 14 of the band dividing unit 2, the low-frequency component and the high-frequency component subjected to the band division are combined in the L-channel audio signal and the R-channel audio signal, respectively, and combined. 1 is output from the band dividing unit 2 (“Low + High L” shown in FIG. 1 indicates a combined signal of the L side channel, and “Low + High R” indicates a combined signal of the R side channel).

  On the other hand, the audio signal in the middle frequency band that has passed through the second low-pass filter unit 11 and the second high-pass filter unit 13 is multiplied by −1 in the phase inverting unit 15 to be phase-inverted. By performing phase inversion in the phase inversion unit 15 in this way, it becomes possible to reduce interference between signals at the time of combining processing in the addition units 4 to 7 shown in FIG. Note that the processing in the phase inversion unit 15 is not always required. In the present embodiment, the order of the Butterworth filter used in the filter units 10 to 13 is the third order. Is going.

  The sound image localization balance setting unit 8 and the sound image localization fader setting unit 9 are operation means provided as an on-vehicle car audio operation unit or an operation panel of a car navigation system.

  The sound image localization balance setting unit 8 is operated when adjusting the localization position of the sound image in the left-right direction. In the sound image localization balance setting unit 8, the basic position (a position where the left and right balances are equal) is defined as 0. When the sound image localization balance setting unit 8 is operated to the left side, the balance is set according to the operation amount. The signal is set to vary from 0 to -1. On the other hand, when the sound image localization balance setting unit 8 is operated to the right side, the balance signal is set to vary from 0 to +1 according to the operation amount.

  The sound image localization fader setting unit 9 is operated when adjusting the localization position of the sound image in the front-rear direction. In the sound image localization fader setting unit 9, the basic position (a position where the front and rear balance is equal) is defined as 0, and when the sound image localization fader setting unit 9 is operated backward, the fader is set according to the operation amount. The signal is set to vary from 0 to -1. On the other hand, when the sound image localization fader setting unit 9 is operated closer to the front side, the fader signal is set to vary from 0 to +1 in accordance with the operation amount.

  FIG. 4 is a block diagram showing a schematic configuration of the localization control unit 3. The localization control unit 3 adjusts the gain of the middle frequency component based on the balance signal set by the operation of the sound image localization balance setting unit 8 and the fader signal set by the operation of the sound image localization fader setting unit 9. Have a role.

  As shown in FIG. 4, the localization control unit 3 includes a subtraction unit (stereo component extraction unit) 20, an addition unit (monaural component extraction unit) 21, an addition unit (middle frequency component synthesis unit) 22 to 25, The first gain unit 26, the second gain unit 27, and a weighting unit (left / right weighting addition means, front / rear weighting addition means) 28 are provided.

  The subtracting unit 20 obtains the mid-frequency component audio signal (“Mid R” shown in FIG. 4) in the R-side channel from the mid-frequency component audio signal (“Mid L” shown in FIG. 4) in the L-side channel. By subtracting, the monaural signal, that is, the center component is removed from the audio signal of the middle frequency component, and the stereo component is extracted.

  The first gain unit 26 and the second gain unit 27 have a role of performing predetermined weighting on the stereo component signal from which the center component has been removed by the subtraction unit 20. The weighting process in the first gain unit 26 and the second gain unit 27 cooperates with the weighting process in the third gain unit of the weighting unit 28 to be described later. The output level of the middle frequency component audio signal added to the high frequency component audio signal is too high or too low compared to the low frequency component and high frequency component audio signals. This is a process that is performed in order to avoid this.

  In the first gain unit 26 shown in the present embodiment, 0.7071 (= 1 / √2) is applied to the signal from which the center component has been removed, and the second gain unit 27 removes the center component. The weighted signal is weighted by −0.7071 (= −1 / √2). The difference between the positive and negative values of the weighting process is intended to correct the phase in the signal synthesizing process in the adders 4 to 7.

  By this weighting process, when the 2-channel audio signal (the L-side channel audio signal and the R-side channel audio signal) is a signal having no correlation between the channels, that is, a stereo signal, It is possible to suppress signal interference in the synthesis process.

  On the other hand, the adding unit 21 performs an audio signal (“Mid L” shown in FIG. 4) of the mid-frequency component of the L side channel and an audio signal (“Mid R” shown in FIG. 4) of the mid-frequency component of the R side channel. )). The audio signals in the middle frequency components of the L-side channel and the R-side channel added by the adding unit 21 are output to the weighting unit 28.

  FIG. 5 is a block diagram showing a schematic configuration of the weighting unit 28. As shown in FIG. 5, the weighting unit 28 includes a third gain unit 30, multiplication units 31 to 36, a first gain setting unit 37, and a second gain setting unit 38.

  The third gain unit 30 has a role of weighting the audio signals in the mid-frequency components of the L-side channel and the R-side channel added by the adding unit 21 of the localization control unit 3. The weighting ratio is adjusted according to the weighting ratios in the first gain unit 26 and the second gain unit 27 described above. In the third gain unit 30 according to the present embodiment, 0.5 weighting is performed.

  Based on the balance signal acquired from the sound image localization balance setting unit 8, the first gain setting unit 37 sets a gain value by which the audio signal of the middle frequency component is multiplied by the multiplication unit 31 and the multiplication unit 32. Have a role.

  The first gain setting unit 37 sets the gain for the balance signal in accordance with the relationship as shown in FIG. As shown in FIG. 6A, when the balance signal is a value between 0 and -1, the sound image localization balance setting unit 8 is operated to the left side. In this case, the first gain setting unit 37 does not reduce the gain (gain output corresponding to the control signal G1L in FIGS. 5 and 6) of the multiplication unit 31 that performs the multiplication process on the audio signal of the L-side channel (0 dB). The gain of the multiplier 32 that performs multiplication on the audio signal of the R side channel (gain output corresponding to the control signal G1R in FIGS. 5 and 6) is proportional to the decrease in the value of the balance signal. To reduce. In this way, when the sound image localization balance setting unit 8 is operated to the left, the gain of the R-side channel in the mid-frequency component is reduced by reducing the gain of the R-channel audio signal. Thus, the localization position of the sound image can be moved to the left side due to the difference in gain in the mid-frequency components between the L-side channel and the R-side channel.

  On the other hand, as shown in FIG. 6A, when the balance signal is a value between 0 and +1, the sound image localization balance setting unit 8 is operated to the right side. In this case, the first gain setting unit 37 does not reduce the gain (gain output corresponding to the control signal G1R in FIGS. 5 and 6) of the multiplication unit 32 that performs the multiplication process on the audio signal of the R side channel (0 dB). And the gain of the multiplier 31 that performs the multiplication process on the audio signal of the L side channel (gain output corresponding to the control signal G1L in FIGS. 5 and 6) is inversely proportional to the increase in the value of the balance signal. To reduce. In this way, when the sound image localization balance setting unit 8 is operated to the right, the gain of the L side channel in the mid-frequency component is reduced by reducing the gain of the audio signal of the L side channel. Thus, the localization position of the sound image can be moved to the right due to the difference in gain in the mid-frequency components of the L side channel and the R side channel.

  Based on the fader signal acquired from the sound image localization fader setting unit 9, the second gain setting unit 38 sets a gain value for multiplying the audio signal of the mid-frequency component by the multiplication unit 33 to the multiplication unit 36. Have a role.

  The second gain setting unit 38 sets the gain for the fader signal according to the relationship shown in FIG. As shown in FIG. 6B, when the fader signal has a value between 0 and -1, the sound image localization fader setting unit 9 is operated toward the rear side. In this case, the second gain setting unit 38 does not reduce the gains of the multiplying unit 34 and the multiplying unit 36 that multiply the rear audio signal (gain output corresponding to the control signal G2R in FIGS. 5 and 6). (While maintaining 0 dB), the gains of the multiplier 33 and the multiplier 35 that perform multiplication on the front audio signal (the gain output corresponding to the control signal G2F in FIGS. 5 and 6) are Reduce in proportion to the decrease in value. In this way, when the sound image localization fader setting unit 9 is operated backward, by reducing the gain in the front audio signal, the front gain in the mid-frequency component is reduced, The localization of the sound image can be moved to the rear side due to the difference in gain between the rear side and front side mid-frequency components.

  On the other hand, as shown in FIG. 6B, when the balance signal is a value between 0 and +1, the sound image localization fader setting unit 9 is operated closer to the front side. In this case, the second gain setting unit 38 does not reduce the gains (gain outputs corresponding to the control signal G2F in FIGS. 5 and 6) of the multiplying unit 33 and the multiplying unit 35 that multiply the front audio signal. (While maintaining 0 dB), the gains of the multiplier 34 and the multiplier 36 that perform multiplication on the rear audio signal (gain output corresponding to the control signal G2R in FIGS. 5 and 6) Decrease in inverse proportion to the increase in value. In this way, when the sound image localization fader setting unit 9 is operated closer to the front side, the rear gain in the mid-frequency component is reduced by reducing the gain in the rear audio signal. Thus, the localization position of the sound image can be moved to the front side due to the difference in gain between the rear side and front side mid-frequency components.

  The multipliers 31 to 36 perform multiplication processing based on the control signals G1L, G1R, G2F, G2R based on the gains set in the first gain setting unit 37 and the second gain setting unit 38, and the audio signal. The weight signals W1 to W4 weighted corresponding to the sound image localization control set by the sound image localization balance setting unit 8 and the sound image localization fader setting unit 9 are added to the addition unit 22 to the addition unit 25 of the localization control unit 3, respectively. Output for.

  The adding unit 22 to the adding unit 25 are weight signals W1 to W1 relating to the stereo component audio signal weighted in the first gain unit 26 and the second gain unit 27 and the monaural component (center component) output from the weighting unit 28. The signal subjected to the addition processing in the addition unit 22 to the addition unit 25 has a role of performing addition with W4, and the sound image localization is performed as localization control signals C1 to C4 for controlling the localization of the center component. It is output to each of the adding unit 4 to the adding unit 7 of the control device 1.

  In the addition unit 4 to the addition unit 7 of the sound image localization control device 1, localization control in the middle frequency component is performed on the audio signal in which the low frequency component and the high frequency component output from the band dividing unit 2 are synthesized. The signals C1 to C4 are added. In this way, by adding the audio signal of the middle frequency component in which the localization control of the sound image based on the monaural component is performed to the audio signal composed of the low and high frequency components in the adding unit 4 to the adding unit 7, It is possible to generate an audio signal in which only the vocal sound portion of the mid-frequency component is effectively controlled for localization.

  Each audio signal (Front R, Rear R, Front L, Rear L) subjected to addition processing in the addition unit 4 to the addition unit 7 is amplified in a power amplifier (not shown), and then the vehicle signal as shown in FIG. A speaker 41 installed in front of the right side in the room 40 (a speaker from which the audio signal Front R is output), a speaker 42 installed in the rear side of the right side (a speaker from which the audio signal Rear R is output), and a speaker installed in front of the left side Corresponding audio signals are output to 43 (the speaker from which the audio signal Front L is output) and the speaker 44 (the speaker from which the audio signal Rear L is output) installed on the left side.

  Next, the sound image localization control device 1 according to the present embodiment is used to operate the sound image localization balance setting unit 8 and the sound image localization fader setting unit 9 to be installed in front of the right side in the passenger compartment 40. The effect of controlling the localization position of the sound image is shown by showing the output waveform of the audio signal output from the speaker 41 installed after the right side, the speaker 42 installed after the right side, the speaker 43 installed before the left side, and the speaker 44 installed after the left side. explain.

  The graphs shown in FIGS. 8 to 14 show the speaker 41 installed on the right front, the speaker 42 installed on the right rear, and the left front when the sound image localization balance setting unit 8 and the sound image localization fader setting unit 9 are operated. It is the figure which showed the output waveform of the audio signal in the monaural audio | voice or stereo audio | voice output from the speaker 43 installed in left and the speaker 44 installed after the left side.

  Here, the sound source input to the sound image localization control device 1 is an M-sequence code having a sampling rate of 48 kHz and a code length of 32,767, and the monaural sound source has the same code for the L side channel and the R side channel. A stereo sound source is a sound source in which the L side channel and the R side channel have different signs and are substantially uncorrelated. Further, the sound source for only the L-side channel shown in FIG. 10 is obtained by inputting an M-sequence code only to the L-side channel.

  Since the stereo sound source remarkably represents so-called sound quality and realism, when the output waveform of the stereo sound source changes greatly due to the operation of the sound image localization balance setting unit 8 or the sound image localization fader setting unit 9. It can be determined that the sound quality and the sense of presence are greatly influenced in the localization control of the sound image.

  On the other hand, the monaural sound source is a sound source of the center component of the middle frequency component (sound source corresponding to vocal sound) that is subjected to localization control based on the balance signal and the fader signal in the weighting unit 28 of the sound image localization control device 1. In the localization control unit 3, localization control processing is performed by the weighting unit 28 on the center component audio signal in the mid-frequency components of the L-side channel and the R-side channel added by the addition unit 21. Since the audio signal input to the weighting unit 28 is a signal of the added mid-frequency component, the signal of the component common to the audio signals of the L side channel and the R side channel, that is, the characteristics as a monaural sound source. Have strong.

  For this reason, when the output waveform of the monaural sound source changes greatly due to the operation of the sound image localization balance setting unit 8 or the sound image localization fader setting unit 9, the localization position of the sound image is effectively controlled according to the operation. It can be determined that it is possible.

  FIG. 8 shows the output waveform of a monaural sound source, FIG. 9 shows the output waveform of a stereo sound source, and both FIG. 8 and FIG. 9 have the balance signal value set to 0 and the fader signal value set to 0. ing.

  Comparing the output waveform shown in FIG. 8 and the output waveform shown in FIG. 9, it can be seen that the monaural sound source and the stereo sound source have almost the same characteristics and are output as they are without being processed.

  FIG. 10 is similar to FIGS. 8 and 9 and outputs the audio signal of the monaural sound source only to the L side channel of the sound image localization control device 1 with the balance signal value set to 0 and the fader signal value set to 0. In this case, output waveforms of audio signals output from the four speakers 41 to 44 are shown.

  When an audio signal is output only to the L-side channel of the sound image localization control device 1, as shown in FIG. 10, the audio signal (Front R) output from the speaker 41 installed in front of the right side and the speaker installed in the rear side of the right side. A crosstalk component is generated in the output waveform of the audio signal (Rear R) output from 42.

  However, this crosstalk component is limited to only the mid-frequency component, and the signal level of the output waveform generated by the crosstalk is about 12 dB lower than the signal level of the L side channel. . For this reason, even when a stereo sound source is input to the sound image localization control device 1, the interference between the L side channel and the R side channel is sufficiently small, which affects the sound quality and the sense of presence. It can be judged that it does not affect.

  FIG. 11 shows the output waveform of a monaural sound source, FIG. 12 shows the output waveform of a stereo sound source, and both FIG. 11 and FIG. 12 set the value of the balance signal to -1 and the value of the fader signal to 0. Has been.

  When the output waveform shown in FIG. 11 is compared with the output waveform shown in FIG. 12, the output waveform of the signal shown in FIG. 12 showing the output waveform of the stereo sound source is shown even though the value of the balance signal is set to -1. FIG. 9 shows waveform characteristics substantially the same as those in FIGS. 8 and 9 in which the value of the balance signal is set to zero. As described above, in the sound image localization control device 1 according to the present embodiment, the sound quality and the sense of presence of the sound source are remarkably achieved even when the value of the balance signal is changed by operating the balance setting unit 8 for sound image localization. It can be said that the possibility of greatly changing the output waveform of the stereo sound source component shown is low.

  On the other hand, the output waveform of the signal in FIG. 11 showing the output waveform of the monaural sound source has a signal level of 20 dB in the middle frequency band in the output waveform of the audio signal (Front R) output from the speaker 41 installed in front of the right side. The signal level in the mid-frequency band in the output waveform of the audio signal (Rear R) output from the speaker 42 installed on the right side is attenuated by about 20 dB. Therefore, for a monaural sound source, the signal level in the middle frequency component of the audio signal (Front L) output from the speaker 43 installed on the left front side and the audio level output from the speaker 44 installed on the left side front Since the signal level in the mid-frequency component of the signal (Rear L) is relatively increased by about 20 dB, the sound image localization is moved to the left side, and the stereo setting is made by the setting of the sound image localization balance setting unit 8. The localization of only the center component (middle frequency band having a monaural component) including vocal sound or the like is controlled while maintaining a feeling, that is, a sense of presence.

  13 shows the output waveform of a monaural sound source, FIG. 14 shows the output waveform of a stereo sound source, and both FIG. 13 and FIG. 14 set the value of the balance signal to −1 and the value of the fader signal to 1. Has been.

  Comparing the output waveform shown in FIG. 13 with the output waveform shown in FIG. 14, the output waveform of the stereo sound source is set even though the value of the balance signal is set to −1 and the value of the fader signal is set to 1. The output waveform of the signal shown in FIG. 14 shows waveform characteristics substantially the same as those in FIGS. 8 and 9 in which the value of the balance signal is set to 0 and the fader signal is set to 0. Thus, in the sound image localization control apparatus 1 according to the present embodiment, the sound image localization balance setting unit 8 is operated to change the value of the balance signal, and the sound image localization fader setting unit 9 is further operated to operate the fader. Even when the value of the signal is changed, it is unlikely that the output waveform of the stereo sound source component that significantly shows the sound quality and the sense of presence of the sound source will be changed greatly.

  On the other hand, the output waveform of the signal of FIG. 13 showing the output waveform of the monaural sound source has a signal level of 20 dB in the middle frequency band of the output waveform of the audio signal (Front R) output from the speaker 41 installed in front of the right side. In addition, the signal level in the middle frequency band of the output waveform of the audio signal (Rear R) output from the speaker 42 installed after the right side is attenuated by about 40 dB. Furthermore, the signal level in the mid frequency band of the output waveform of the audio signal (Rear L) output from the speaker 44 installed on the left side is attenuated by about 20 dB.

  Thus, for a monaural sound source, the audio signal output from the speakers 41 and 42 installed on the right side is set by operating the sound image localization balance setting unit 8 and setting the value of the balance signal to -1. Since the signal level in the middle frequency component of the audio signal output from the speakers 43 and 44 installed on the left side is relatively higher by about 20 dB than the signal level in the middle frequency component, the localization of the sound image is , Will move to the left side. Further, by operating the sound image localization fader setting unit 9 to set the value of the fader signal to 1, the signal level in the middle frequency component of the audio signal output from the speakers 42 and 44 installed on the rear side is determined. However, since the signal level in the middle frequency component of the audio signal output from the speakers 41 and 43 installed on the front side is relatively higher by about 20 dB, the localization of the sound image moves toward the front side. .

  Therefore, by operating the sound image localization balance setting unit 8 and the sound image localization fader setting unit 9, a center component (middle frequency having a monaural component) including a vocal sound or the like is maintained while maintaining a sense of stereo, that is, presence. It is possible to control the localization only in the band) in the front-rear direction and the left-right direction.

  As described above, by using the sound image localization control device 1 according to the present embodiment, based on the balance signal and the value of the fader signal set by the sound image localization balance setting unit 8 and the sound image localization fader setting unit 9. Thus, gain control corresponding to the localization position control of the sound image can be performed on the monaural component (center component) in the mid-frequency band, and the monaural component in the mid-frequency band where the localization position control is performed The audio signals of the stereo component and the low and high frequency components in the frequency band can be added and output from the speakers 41 to 44. For this reason, it is possible to effectively perform localization control with respect to the monaural component (center component) in the mid-frequency band that constitutes the vocal sound, and to perform localization control of the sound image without impairing the sound quality or presence. Is possible.

  In addition, by adjusting the gain of the monaural sound source in the mid-frequency component in this way, it is possible to effectively control the localization position, so that the sound quality and presence of the output sound source can be maintained without loss. Thus, it is possible to perform sound image localization control in the center component without being affected by reflected waves or shielding in the passenger compartment.

  Although the sound image localization control device 1 according to the present embodiment has been described in detail with reference to the drawings, the sound image localization control device according to the present invention is limited to the content described in the present embodiment. It is not a thing. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, the output waveform of the audio signal shown in FIGS. 8 to 14 can be changed according to the gain setting for the balance signal and the fader signal shown in FIGS. By changing the characteristics of the output waveform controlled in accordance with the operation of the setting unit 8 and the sound image localization fader setting unit 9, the localization position of the sound image can be arbitrarily controlled.

  For example, the graphs shown in FIGS. 15A and 15B are graphs showing relationships different from the gain setting relationships for the balance signal and the fader signal shown in FIGS. 6A and 6B. By setting the gain for the balance signal and the fader signal using the relationship shown in FIG. 15, the output waveform controlled according to the operation of the sound image localization balance setting unit 8 and the sound image localization fader setting unit 9 is set. The characteristics can be adjusted so as to be different from the characteristics of the output waveform as shown in FIGS.

It is the block diagram which showed schematic structure of the sound image localization control apparatus which concerns on this Embodiment. It is the block diagram which showed schematic structure of the band division part which concerns on this Embodiment. It is the figure which showed the filter characteristic according to the band by which a band division is performed in the band division part which concerns on this Embodiment. It is the block diagram which showed schematic structure of the localization control part which concerns on this Embodiment. It is the block diagram which showed schematic structure of the weighting part which concerns on this Embodiment. (A) is the figure which showed an example of the relationship of the gain set according to a balance signal in the 1st gain setting part which concerns on this Embodiment, (b) is the 2nd which concerns on this Embodiment. It is the figure which showed an example of the relationship of the gain set according to a fader signal in a gain setting part. It is the figure which showed the example of arrangement | positioning of the speaker installed in the vehicle provided with the sound image localization control apparatus which concerns on this Embodiment. It is the figure which showed the output waveform of each speaker when the audio signal of a monaural sound source is input to the sound image localization control device according to the present embodiment, the balance signal is set to 0, and the fader signal is set to 0. It is the figure which showed the output waveform of each speaker when the audio | voice signal of a stereo sound source is input with respect to the sound image localization control apparatus which concerns on this Embodiment, a balance signal is set to 0, and a fader signal is set to 0. The output waveform of each speaker when the audio signal of the monaural sound source is input only to the L side channel and the balance signal is set to 0 and the fader signal is set to 0 for the sound image localization control device according to the present embodiment. FIG. It is the figure which showed the output waveform of each speaker in case the audio signal of a monaural sound source is input with respect to the sound image localization control apparatus which concerns on this Embodiment, a balance signal is set to -1 and a fader signal is set to 0. It is the figure which showed the output waveform of each speaker in case the audio signal of a stereo sound source is input with respect to the sound image localization control apparatus which concerns on this Embodiment, a balance signal is set to -1 and a fader signal is set to 0. It is the figure which showed the output waveform of each speaker in case the audio signal of a monaural sound source is input with respect to the sound image localization control apparatus which concerns on this Embodiment, a balance signal is set to -1 and a fader signal is set to 1. FIG. It is the figure which showed the output waveform of each speaker in case the audio signal of a stereo sound source is input with respect to the sound image localization control apparatus which concerns on this Embodiment, a balance signal is set to -1 and a fader signal is set to 1. FIG. (A) is the figure which showed the other example of the relationship of the gain set according to a balance signal in the 1st gain setting part which concerns on this Embodiment, (b) is based on this Embodiment It is the figure which showed the other example of the relationship of the gain set according to a fader signal in a 2nd gain setting part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sound image localization control apparatus 2 ... Band division part (band division means)
3 ... Localization control units 4 to 7 ... (in the sound image localization control device) addition unit (band synthesis means)
8: Balance setting section for sound image localization (balance setting means)
9: Fader setting unit for sound image localization (fender setting means)
DESCRIPTION OF SYMBOLS 10 ... 1st low pass filter part 11 (in a band division part) ... 2nd low pass filter part 12 (in a band division part) ... 1st high pass filter part 13 (in a band division part) ... 2nd high pass (in a band division part) Filter unit 14 ... Adder unit 15 (in the band dividing unit) ... Phase inversion unit 20 (in the band dividing unit) ... Subtracting unit (in the stereo control unit) (stereo component extracting means)
21... Adder (in monaural component extracting means)
22 to 25: Adder (in the localization control unit) (middle frequency component synthesis means)
26... First gain section 27 (in the localization control section)... Second gain section 28 (in the localization control section)... Weighting section (in the localization control section)
30 ... third gain units 31 to 36 (in the weighting unit) ... multiplication unit 37 (in the weighting unit) ... first gain setting unit 38 (in the weighting unit) ... second gain setting unit 40 (in the weighting unit) ... 41 ... Speaker (right speaker, front speaker)
42 ... Speaker (right speaker, rear speaker)
43 ... Speaker (left speaker, front speaker)
44 ... Speaker (left speaker, rear speaker)

Claims (3)

A sound image localization control device for performing a localization control process of a sound image with respect to an audio signal of a stereo sound source output to the right speaker and the left speaker in a vehicle interior having at least a right speaker and a left speaker,
A balance setting means for performing a horizontal setting in the audio signal;
Band division means for dividing the audio signal of the stereo sound source into low and high frequency components and left and right frequency components in the left and right channels;
A monaural component that extracts a monaural component audio signal having a common signal characteristic based on the midband frequency component audio signal in the left channel and the midband frequency component audio signal in the right channel divided by the band dividing means. Component extraction means;
Stereo for extracting audio signals of stereo components having different signal characteristics based on the audio signal of the mid-frequency component in the left channel and the audio signal of the mid-frequency component in the right channel divided by the band dividing means Component extraction means;
By adding a weight corresponding to the left and right balance amount set by the balance setting unit to the monaural component audio signal extracted by the monaural component extraction unit, the monaural component audio signal in the left channel, and Left and right weighting adding means for generating a mono component audio signal in the right channel;
The stereo component extracted by the stereo component extraction unit for each of the monaural component audio signal in the left channel and the monaural component audio signal in the right channel to which the weighting is added by the left and right weight addition unit. A middle frequency component synthesizing means for generating a middle frequency component audio signal in the right channel and a middle frequency component audio signal in the left channel by synthesizing the audio signal of
Combining the audio signal of the mid-frequency component in the left channel generated by the mid-frequency component synthesis means and the audio signal of the low-high frequency component in the left channel divided by the band dividing means; Band synthesizing means for synthesizing the audio signal of the middle frequency component in the right channel generated by the middle frequency component synthesizing means and the audio signal of the low and high frequency component in the right channel divided by the band dividing means; A sound image localization control device comprising: A sound image localization control device for performing a localization control process of a sound image for an audio signal of a stereo sound source output to the front speaker and the rear speaker in a vehicle interior including at least a front speaker and a rear speaker,
A fader setting means for setting the localization in the front-rear direction in the audio signal;
Band division means for dividing the audio signal of the stereo sound source into low and high frequency components and left and right frequency components in the left and right channels;
A monaural component that extracts a monaural component audio signal having a common signal characteristic based on the midband frequency component audio signal in the left channel and the midband frequency component audio signal in the right channel divided by the band dividing means. Component extraction means;
Stereo for extracting audio signals of stereo components having different signal characteristics based on the audio signal of the mid-frequency component in the left channel and the audio signal of the mid-frequency component in the right channel divided by the band dividing means Component extraction means;
The monaural component audio signal for the front speaker is added to the monaural component audio signal extracted by the monaural component extraction unit by adding a weight corresponding to the front and rear fader values set by the fader setting unit. Front and rear weighting adding means for generating a mono component audio signal for the rear speaker;
The audio signal of the monaural component for the front speaker to which the weight is added by the front-rear weight addition unit is divided into the audio signal for the front speaker in the right channel and the left channel, and further, the audio signal for the rear speaker A mono component audio signal is divided into audio signals for the rear speakers in the right channel and the left channel, and the stereo component audio signal extracted by the stereo component extracting means for all the divided audio signals. By combining the audio signal of the mid-frequency component for the front speaker in the right channel, the audio signal of the mid-frequency component for the rear speaker in the right channel, and the audio signal in the left channel An audio signal of the middle-frequency component for the side speakers, a midrange frequency component synthesis means for generating an audio signal of the middle band frequency components for the rear speakers in the left channel,
For the audio signal of the middle frequency component for the front speaker in the right channel and the audio signal of the middle frequency component for the rear speaker in the right channel synthesized by the middle frequency component synthesis means, The audio signal of the low and high frequency components for the right channel that has been band-divided by the band dividing unit is synthesized, and the mid-frequency component of the front speaker in the left channel that is synthesized by the mid-frequency component synthesizing unit. Band synthesis for synthesizing the audio signal of the low frequency band component for the left channel divided by the band dividing unit with the audio signal and the audio signal of the mid band frequency component for the rear speaker in the left channel And a sound image localization system characterized by comprising: Control device. A sound image localization control device for performing a localization control process of a sound image with respect to an audio signal of a stereo sound source output to each speaker in a vehicle room having at least four speakers on the front, rear, left, and right,
A balance setting means for performing a horizontal setting in the audio signal;
A fader setting means for setting the localization in the front-rear direction in the audio signal;
Band division means for dividing the audio signal of the stereo sound source into low and high frequency components and left and right frequency components in the left and right channels;
A monaural component that extracts a monaural component audio signal having a common signal characteristic based on the midband frequency component audio signal in the left channel and the midband frequency component audio signal in the right channel divided by the band dividing means. Component extraction means;
Stereo for extracting audio signals of stereo components having different signal characteristics based on the audio signal of the mid-frequency component in the left channel and the audio signal of the mid-frequency component in the right channel divided by the band dividing means Component extraction means;
By adding a weight corresponding to the left and right balance amount set by the balance setting unit to the monaural component audio signal extracted by the monaural component extraction unit, the monaural component audio signal in the left channel, and Left and right weighting adding means for generating a mono component audio signal in the right channel;
By adding a weight corresponding to the front and rear fader values set by the fader setting means to the monaural component audio signal in the left channel generated by the left and right weight addition means, the front speaker for the left channel And a mono component audio signal for the rear speaker in the left channel, and a mono component audio signal in the right channel generated by the left-right weighting adding unit. By adding weights corresponding to the front and rear fader amounts set by the fader setting means, the monaural component audio signal for the front speaker in the right channel and the rear speaker mono in the right channel are added. Front and rear weighting addition means for generating an audio signal Le component,
Stereo component audio extracted by the stereo component extraction means for all the audio signals weighted corresponding to the left and right balance amounts and the front and rear fader amounts by the left and right weight addition means and the front and rear weight addition means. By combining signals, an audio signal of the mid-frequency component for the front speaker in the right channel, an audio signal of the mid-frequency component for the rear speaker in the right channel, and the front side in the left channel Midband frequency component synthesizing means for generating a midband frequency component audio signal for the speaker and a midband frequency component audio signal for the rear speaker in the left channel;
For the audio signal of the middle frequency component for the front speaker in the right channel and the audio signal of the middle frequency component for the rear speaker in the right channel synthesized by the middle frequency component synthesis means, The audio signal of the low and high frequency components for the right channel that has been band-divided by the band dividing unit is synthesized, and the mid-frequency component of the front speaker in the left channel that is synthesized by the mid-frequency component synthesizing unit. Band synthesis for synthesizing the audio signal of the low frequency band component for the left channel divided by the band dividing unit with the audio signal and the audio signal of the mid band frequency component for the rear speaker in the left channel A sound image localization system characterized by comprising: Control device.

Images