JP2007184758A - Sound reproduction device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a feeling of imbalance of sound image localization in a cabin and a feeling of booming of a sound field. <P>SOLUTION: A sound image localization correction processing unit 1 perform delay processing for an audio signal of an L channel, an audio signal of an R channel, and an addition signal of the audio signal of the L channel and the audio signal of the R channel according to the number of seats at listening positions, and adds the addition signal having been delayed to the audio signals of the respective channels having been delayed. A sound quality improvement processing unit 2 divides the signals of the respective channels from the sound image localization correction processing unit 1 into three bands of high, middle, and low frequencies and performs dynamic range compression processing for the signals divided into the respective bands. A time delay correction unit 3 performs delay processing for the signals of the respective channels from the sound quality improvement processing unit 2 according to the seats at the listening positions. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an on-vehicle sound reproducing device.

  In the in-vehicle sound reproducing apparatus, since the positional relationship with respect to the speaker differs depending on the seat, a difference occurs in the arrival time from the speaker to the listening position, thereby causing an unbalanced feeling of sound image localization.

  Moreover, in a sound field in a closed space such as a passenger compartment, a standing wave is present, and there is a feeling of being crowded. Furthermore, depending on the vehicle model, the speaker is mounted on the door, and the sound is reproduced from a low position, which may affect the feeling of being crowded.

  Conventionally, in order to reduce the unbalanced feeling of sound image localization, the left / right and front / rear playback balance is corrected by level correction (fader function). Further, a technique for performing a delay process for matching the listening timing of the reproduced sound from the speaker from the distance from the speaker to the listening position is also known.

In addition, a technique for performing frequency correction processing with a graphic equalizer is known in order to reduce the feeling of being crowded. Further, Patent Document 1 discloses a technique for improving the sound field feeling by adding each signal to the reproduced signal when a set level is exceeded on the low frequency side and the high frequency side to correct the sound field.
JP-A-3-212000

  However, when level correction or delay processing is performed in order to reduce the unbalanced feeling of sound image localization, only processing for a specific listening position can be performed, so that there is a problem that the target person is limited to one person. It was.

  In addition, the technique for performing frequency correction processing to reduce the feeling of stagnation and the technique disclosed in Patent Document 1 may not be very effective depending on the vehicle type and speaker configuration. Further, when the tweeter is attached, the sound quality is changed by performing the frequency correction process because the high sound range is excessively emphasized. In particular, when the tweeter is pillar-mounted, the tweeter is close to the listener, so the change in sound quality is noticeable.

  The present invention has been made in view of the above, and an object of the present invention is to reduce an unbalanced feeling of sound image localization not only at one listening position in an on-vehicle sound reproducing device.

  It is another object of the present invention to reduce the feeling of the sound field in the vehicle without excessively changing the original sound quality of the sound source even if a tweeter is attached, regardless of the vehicle type or speaker configuration.

  The sound reproduction apparatus of the present invention is a sound reproduction apparatus for reproducing a 2-channel audio signal, a first adding means for adding the audio signal of one channel and the audio signal of the other channel to generate an addition signal; The first delay means for delaying the audio signal of the one channel, the audio signal of the other channel, and the addition signal, and the addition signal output from the first delay means, A second adding means for adding to each channel's audio signal output from one delay means; and the audio signal of each channel to which the added signal has been added by the second adding means, respectively, for high frequency and middle frequency. Is divided into three bands, band and low band, and dynamic range compression processing is applied to each band-divided signal. When a tweeter is used to reproduce the audio signal of each channel, compression means for lowering the signal level of the high frequency compared to other bands, and the audio signal of each channel output from the compression means In each of the first delay means and the second delay means, a second delay means for performing a delay process, and a position of a speaker for reproducing the audio signal of each channel and a listening position of the reproduced sound, respectively. And a control means for controlling a delay time given to the signal.

  According to the present invention, an audio signal of one channel and an audio signal of the other channel are added to generate an addition signal, and the audio signal of one channel, the audio signal of the other channel, and the addition signal are listened to. Each delay process is performed according to the position, and the added signal subjected to the delay process is added to the audio signal of each channel subjected to the delay process, and the added signal is added to the audio signal of each channel. Since each delay process is performed according to the listening position, it is possible to reduce the sense of unbalance in sound image localization, not limited to one listening position.

  In addition, the audio signal of each channel to which the addition signal is added is divided into three bands, a high band, a middle band, and a low band, and a dynamic range compression process is performed on each band-divided signal. The sound quality of the sound source itself can be improved, regardless of the vehicle type and speaker configuration, and even if a tweeter is attached, the sound quality of the sound field inside the vehicle is reduced without excessively changing the sound quality of the sound source. can do.

  Hereinafter, the best mode for carrying out the sound reproducing apparatus of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a sound reproducing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the sound reproduction apparatus of this embodiment includes a sound image localization correction processing unit 1 that performs localization improvement processing on L channel and R channel audio signals, and analyzes sound source characteristics to improve sound quality. A sound quality improvement processing unit 2 that performs processing, a time delay correction unit 3 that performs delay processing on an audio signal, an input unit 4 that receives an operation input from a user and outputs an operation signal, and controls each unit provided in the apparatus And a control unit 5.

  FIG. 2 is a block diagram showing a sound image localization correction processing unit of the sound reproducing apparatus shown in FIG. As shown in FIG. 1, the sound image localization correction processing unit 1 multiplies one of the L-channel audio signals branched into two after input by a coefficient and the other of the L-channel audio signals by a coefficient. A multiplier 11B, a multiplier 11C for multiplying one of the R-channel audio signals branched into two after input, a multiplier 11D for multiplying the other of the R-channel audio signals by a coefficient, and a multiplier An adder 12A for adding the output signal of 11A and the output signal of the multiplier 11C, an adjustment filter 13A for adjusting the output signal of the multiplier 11B, and an adjustment for adjusting the output signal of the adder 12A Filter 13B, adjustment filter 13C for adjusting the output signal of multiplier 11D, and delay circuit 14 for delaying the output signal of adjustment filter 13A A delay circuit 14B for delaying the output signal of the adjustment filter 13B, a delay circuit 14C for delaying the output signal of the adjustment filter 13C, and a multiplier 11E for multiplying the output signal of the delay circuit 14A by a coefficient. A multiplier 11F that multiplies the output signal of the delay circuit 14C by a coefficient, multipliers 11G and 11H that multiply the output signal of the delay circuit 14B branched in two by a coefficient, and an output signal of the multiplier 11E And an adder 12C for adding the output signal of the multiplier 11G, and an adder 12C for adding the output signal of the multiplier 11F and the output signal of the multiplier 11H.

  FIG. 3 is a block diagram showing a basic part in the sound quality improvement processing part of the sound reproducing apparatus shown in FIG. The sound quality improvement processing unit 2 includes two basic units corresponding to each channel. Since the configuration is the same, the configuration will be described by taking one basic unit as an example.

  As shown in FIG. 3, the basic part of the sound quality improvement processing unit 2 includes a low-pass filter 21 that extracts a low-frequency component of one (for example, L channel) audio signal input from the sound image localization correction processing unit 1, and input audio. A mid-pass filter 22 that extracts a mid-frequency component of the signal, a high-pass filter 23 that extracts a high-frequency component of the input audio signal, and a dynamic range compression unit 24A that applies dynamic range compression processing to the output signal of the low-pass filter 21 A dynamic range compression unit 24B that applies dynamic range compression processing to the output signal of the mid-pass filter 22, a dynamic range compression unit 24C that applies dynamic range compression processing to the output signal of the high-pass filter 23, and a dynamic range compression unit A multiplier 25A for multiplying the output signal of 24A by a coefficient; Comprising a multiplier 25B for multiplying the coefficient on the output signal of Nji compression unit 24B, and a multiplier 25C for multiplying the coefficient on the output signal of the dynamic range compressing unit 24C.

  FIG. 4 is a block diagram showing a time delay correction unit of the sound reproducing device shown in FIG. As shown in FIG. 4, the time delay correction unit 3 includes a delay circuit 31 </ b> A that performs a delay process on the L channel audio signal input from the sound quality improvement processing unit 2, and an R channel audio that is input from the sound quality improvement processing unit 2. A delay circuit 31B for performing a delay process on the signal.

  Next, the operation of the sound reproducing device of the present embodiment will be described.

  When the L-channel audio signal and the R-channel audio signal are input to the sound image localization correction processing unit 1, each of them is branched into two. Multiplier 11A multiplies one of the two branched L-channel audio signals by a coefficient and outputs the result to adder 12A. The multiplier 11B multiplies the other of the two branched L-channel audio signals by a coefficient and outputs the result to the adjustment filter 13A.

  The multiplier 11C multiplies one of the two branched R-channel audio signals by a coefficient and outputs the result to the adder 12A. The multiplier 11D multiplies the other of the two branched L-channel audio signals by a coefficient and outputs the result to the adjustment filter 13C.

  The adder 12A adds the L-channel audio signal and the R-channel audio signal multiplied by the coefficients to generate an added signal, and outputs the added signal to the adjustment filter 13B. The adjustment filters 13 </ b> A to 13 </ b> C perform adjustment processing such as emphasis on a low treble range and extraction of a center vocal component for each input signal.

  Next, the delay circuits 14A to 14C perform delay processing on the signals output from the adjustment filters 13A to 13C. The delay time given by the delay circuits 14A to 14C is controlled by the control unit 5 and adjusted according to the number of seats to be subjected to the sound image localization correction process. The number of seats to be subjected to the sound image localization correction process is input to the input unit 4 by the user, and the input unit 4 outputs an operation signal to the control unit 5. The control unit 5 determines this operation signal and controls the delay circuits 14A to 14C.

  For example, it is assumed that two target seats, a driver seat and a passenger seat, are set as the target seats for sound image localization correction processing. In this case, the control unit 5 gives a delay time to the L-channel audio signal and the R-channel audio signal in order to delay the L-channel audio signal and the R-channel audio signal with respect to the addition signal. The delay circuits 14A to 14C are controlled so as not to give a delay time.

  Also, if the seat subject to the sound image localization correction processing is set to one of the driver seat and the passenger seat, the control unit 5 sends the addition signal to the L channel audio signal and the R channel audio signal. Therefore, the delay circuits 14A to 14C are controlled so that a delay time is given to the addition signal and no delay time is given to the L channel audio signal and the R channel audio signal.

  The multiplier 11E multiplies the L-channel audio signal output from the delay circuit 14A by a coefficient and outputs the result to the adder 12B. The multiplier 11F multiplies the R channel audio signal output from the delay circuit 14C by a coefficient and outputs the result to the adder 12C.

  The addition signal output from the delay circuit 14B is branched into two. Then, the multiplier 11G multiplies one addition signal by a coefficient and outputs the result to the adder 12B. Multiplier 11H multiplies the other addition signal by a coefficient and outputs the result to adder 12C.

  The adder 12B adds the addition signal output from the multiplier 11G to the L channel audio signal output from the multiplier 11E, and outputs the result. The adder 12C adds the addition signal output from the multiplier 11H to the R channel audio signal output from the multiplier 11F and outputs the result.

  The L-channel and R-channel audio signals output from the adders 12B and 12C are input to the sound quality improvement processing unit 2 and subjected to sound quality improvement processing. Hereinafter, the processing of the L channel audio signal will be described, but the same processing is applied to the R channel audio signal.

  When the L-channel audio signal output from the adder 12B is input to the basic part of the sound quality improvement processing unit shown in FIG. 3, the low-pass filter 21 extracts the low-frequency component of the input audio signal, and the mid-pass filter 22 extracts a mid-frequency component, and a high-pass filter 23 extracts a high-frequency component. Audio signals that have been band-divided into three bands of low, mid, and high frequencies by the low-pass filter 21, the mid-pass filter 22, and the high-pass filter 23 are input to the dynamic range compression units 24A to 24C, respectively. A dynamic range compression process is performed.

  The dynamic range compression units 24A to 24C monitor the signal level on the frequency axis of the input signal of each band for the input signal, respectively, and lower the signal level when the signal level is higher than a predetermined threshold, When the signal level is lower than the threshold value, the signal level is increased. In this way, the signal level is compressed within a certain range in the entire frequency band.

  Output signals from the dynamic range compression units 24A to 24C are multiplied by coefficients by multipliers 25A to 25C, respectively, and gain adjustment is performed. Thereafter, the signals in each band are added and output.

  FIG. 5 is a conceptual diagram of input signal characteristics of the sound quality improvement processing unit, and FIG. 6 is a conceptual diagram of output signal characteristics of the sound quality improvement processing unit. By applying dynamic range compression processing to the input signal as shown in FIG. 5, a signal whose signal level is compressed within a certain range in the entire frequency band as shown in FIG. 6 is output.

  Here, when a tweeter is mounted in the vehicle interior, the high-frequency signal level in the output signal is suppressed to be lower than in other bands. The presence / absence of the tweeter is input to the input unit 4 by the user, and the input unit 4 outputs an operation signal to the control unit 5. The control unit 5 determines this operation signal, and when there is a tweeter, controls the high range dynamic range compression unit 24C to set the threshold value lower than the other bands.

  The L channel audio signal output from the sound quality improvement processing unit 2 is input to the delay circuit 31A of the time delay correction unit 3, and the R channel audio signal output from the sound quality improvement processing unit 2 is input to the time delay correction unit 3. To the delay circuit 31B. The delay circuits 31A and 31B perform a delay process on each input audio signal.

  The delay time given by the delay circuits 31A and 31B is controlled by the control unit 5, and is adjusted according to where the target seat of the sound image localization correction process is. The seat subject to sound image localization correction processing is input to the input unit 4 by the user, and the input unit 4 outputs an operation signal to the control unit 5. The controller 5 determines this operation signal and controls the delay circuits 31A and 31B.

  For example, it is assumed that the target seat for the sound image localization correction process is set as the driver seat (the right seat). In this case, in order to delay the R channel audio signal with respect to the L channel audio signal, the control unit 5 gives a delay time to the R channel audio signal and does not give a delay time to the L channel audio signal. The delay circuits 31A and 31B are controlled.

  Further, if the seat subject to sound image localization correction processing is set as a passenger seat (left seat), the control unit 5 uses the L channel to delay the L channel audio signal relative to the R channel audio signal. The delay circuits 31A and 31B are controlled so that a delay time is given to the audio signal of No. 1 and no delay time is given to the audio signal of the R channel.

  When the seats to be subjected to the sound image localization correction process are set as both the driver seat and the passenger seat, the control unit 5 outputs the audio signals of the respective channels as they are without giving any delay time. 31B is controlled.

  As described above, according to the present embodiment, the sound image localization correction processing unit 1 adds the L channel audio signal and the R channel audio signal to generate an addition signal, and generates the L channel audio signal and the R channel audio signal. The audio signal and the addition signal are each subjected to delay processing according to the number of seats at the listening position, and the addition signal subjected to the delay processing is added to the audio signal of each channel subjected to the delay processing, The time delay correction unit 3 performs delay processing on the L channel audio signal and the R channel audio signal to which the addition signal has been added according to the seat at the listening position, so that the time delay correcting unit 3 is not limited to one listening position. The unbalanced feeling of sound image localization can be reduced according to the seat at the listening position.

  Also, the sound quality improvement processing unit 2 divides the audio signal of each channel from the sound image localization correction processing unit 1 into three bands, a high band, a middle band, and a low band, respectively, and a signal divided into bands. Since the dynamic range compression processing is applied to the sound source, the sound quality of the sound source itself can be improved, and the feeling of the sound field in the vehicle can be reduced regardless of the vehicle type and the speaker configuration.

  Further, when a tweeter is mounted in the vehicle interior, the threshold value of the high frequency dynamic range compression unit 24C is set lower than the other bands, and the high frequency signal level in the output signal is kept lower than that of the other bands. Therefore, even if the tweeter is attached, it is possible to suppress the high frequency range from being emphasized too much, and to reduce the feeling of the sound field in the vehicle without excessively changing the sound quality.

  In the above description, the case where the input signals are the L channel audio signal and the R channel audio signal has been described. However, the input signal is not limited to this, for example, the down-mixed 2ch in the multichannel 5.1ch signal. It may be a signal.

It is a lineblock diagram showing the sound reproduction device concerning one embodiment of the present invention. It is a block diagram which shows the sound image localization correction process part of the sound reproduction apparatus shown in FIG. It is a block diagram which shows the basic part in the sound quality improvement process part of the sound reproduction apparatus shown in FIG. It is a block diagram which shows the time delay correction | amendment part of the sound reproduction apparatus shown in FIG. It is a characteristic conceptual diagram of the input signal of a sound quality improvement process part. It is a characteristic conceptual diagram of the output signal of a sound quality improvement process part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sound image localization correction | amendment process part 2 Sound quality improvement process part 3 Time delay correction | amendment part 4 Input part 5 Control part 11A-11H, 25A-25C Multiplier 12A-12C Adder 13A-13C Adjustment filter 14A-14C, 31A, 31B Delay Circuit 21 Low-pass filter 22 Middle-pass filter 23 High-pass filter 24A-24C Dynamic range compression unit

Claims (1)

In an audio reproduction device that reproduces a 2-channel audio signal,
First addition means for adding the audio signal of one channel and the audio signal of the other channel to generate an addition signal;
First delay means for applying delay processing to the audio signal of the one channel, the audio signal of the other channel, and the sum signal;
Second addition means for adding the addition signal output from the first delay means to the audio signal of each channel output from the first delay means;
The audio signal of each channel to which the added signal is added by the second adding means is divided into three bands, a high band, a middle band, and a low band, and each band is divided into dynamic bands. When performing a range compression process and using a tweeter to reproduce the audio signal of each channel, compression means for lowering the signal level of the high band compared to other bands,
Second delay means for applying delay processing to the audio signals of the respective channels output from the compression means;
Control means for controlling a delay time given to each signal in the first delay means and the second delay means in accordance with the position of the speaker for reproducing the audio signal of each channel and the listening position of the reproduced sound. A sound reproducing device comprising:

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