JPH10248097A - Acoustic processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always realize an optimum time alignment function without errors by changing a sound velocity value used for calculation for setting delay time in accordance with a temperature situation and setting optimum delay time. SOLUTION: When sound velocity is changed by the temperature change, a control part 1 calculates delay time which is to be given to the sound signals of respective channels, which correspond to that time. The delay time of the respective channels is multiplied by the value of a sampling frequency in an A/D converter 21 in the delay time of the respective channels and delay time is converted into the number of delay samples as a value for controlling delay quantity in DSP 22. The number of the delay samples of the respective channels is set in DSP 22 and DSP 22 delays and outputs the signals of the respective channels in accordance with the number of the delay samples which are set on the sound signals of the respective channels. Thus, the time alignment function becomes valid and a state where all speaker units are artificially in equal distances is realized in a driving seat, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound processing apparatus which can be used in an audio system having a plurality of speaker units.

[0002]

2. Description of the Related Art In a two-channel audio stereo system, in order that sound waves from two-channel loudspeakers of L and R can be heard at the same timing, it is preferable to arrange each loudspeaker at a position equidistant from a listening point. It is said. For the same reason, it is preferable that the distance from the listening point to each speaker is equal even in the in-vehicle audio system such as 2-channel, 4-channel, and 6-channel. In this specification, “channel” means an audio signal supply system corresponding to each of speaker units arranged at different positions.

However, in an automobile, listening points may be a driver's seat, a passenger's seat, a rear seat left and right, and the like, and the installation position of a speaker is limited according to the type of vehicle. In a vehicle audio system, for example, a high-range speaker is often arranged on the left and right of a console in front of a driver's seat, and a low-range speaker is arranged on the left and right behind a rear seat. In the case of six channels, for example, speakers for the mid range are installed at doors on the driver's seat side and the passenger's seat side.

[0004] In such a speaker arrangement, an equal distance from all speakers is not obtained in any seat in the vehicle cabin. Therefore, by setting the delay time for the audio signal for each channel and adjusting the speaker output time, sound waves can be simulated at equal distances from all speakers at the listening point for ideal listening. Some devices have a function (time alignment function) for bringing them into a state.

[0005]

In this time alignment function, a required delay time is given to the audio signal supplied to each speaker based on the distance between the listening point and each speaker. Two speakers having different distances from the listening point will be briefly described. If there are two speakers at different distances from the listening point, the sound wave from the closer speaker will reach the listening point earlier. The distance DN between the closer speaker and the listening point
And the distance DF between the distant speaker and the listening point
When the difference (DF-DN) is calculated, this difference becomes a distance difference corresponding to the sound wave arrival time difference. If a delay is given to the audio signal supplied to the closer speaker by the time corresponding to this distance difference, the listening point In this case, sound waves of the same timing arrive at the same time from both speakers in a pseudo manner.
That is, an ideal listening environment can be obtained regardless of the actual positional relationship between the speakers and the listening points.

Here, the time difference corresponding to the distance difference, that is, the delay time to be given to the audio signal supplied to one speaker by the time alignment function can be obtained by dividing the distance difference by the speed of sound. However, the actual speed of sound changes with temperature. For this reason, in the conventional method in which the delay time is calculated using a certain fixed sound velocity value, an error occurs in the setting of the delay time in the time alignment function depending on the temperature condition at that time, and an optimal listening environment cannot be obtained. There was a problem. This problem is particularly serious in an environment where temperature changes are severe, such as in an automobile.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to always provide an optimal time alignment function in response to a change in temperature.

[0008] For this purpose, as an acoustic processing apparatus for executing a time alignment function, a temperature detecting means for detecting a temperature of an acoustic space formed by a plurality of speaker units, a distance between a set listening point and each speaker unit. A delay control means for setting and controlling a delay time given to the audio signal of each channel by the sound processing means based on the information and a sound velocity value corresponding to the current temperature detected by the temperature detection means. That is, the sound velocity value used for the calculation for setting the delay time is changed according to the temperature condition,
Set the optimal delay time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. It is assumed that this example is a sound processing device mounted on a 6-channel stereo audio system to be mounted on a vehicle. The description will be made in the following order. 1. 1. Configuration of sound processing device Initial setting 3. Time alignment operation

[0010] 1. FIG. 1 is a block diagram of a sound processing apparatus according to an embodiment mounted on a 6-channel stereo audio system having three ways of L / R. For example, a sound signal SIN is input to this sound processing device from a unit such as a CD player,
The processing is performed as a digital preamplifier unit (crossover network) for supplying the audio signal SIN to a 6-channel speaker unit.

The audio signal SIN is input to the preamplifier unit 2 of the sound processing device, where it is subjected to amplification processing as a power amplifier and conversion to a 6-channel signal (3-way signal for each frequency band). The preamplifier unit 2 has a delay function for time alignment. The preamplifier unit 2 outputs six-channel audio signals to be supplied to the six-channel speakers. The signals of the six channels in this example are the audio signal SHL, which is the high frequency component of the L channel, and the middle frequency component of the L channel, because the signals of each of the L and R channels are divided into high, middle, and low frequencies. An audio signal SML, an audio signal SLL that is an L channel low frequency component, an audio signal SHR that is an R channel high frequency component, and an audio signal SM that is an R channel middle frequency component
The audio signal SLR is a low frequency component of the R and R channels.

FIG. 4 is an image diagram of the arrangement state in the vehicle interior. The audio signal SHL is supplied to, for example, a high-range left speaker HL installed on the left side of the front console in the vehicle as shown in FIG. The audio signal SML is, for example, a middle-range left speaker ML installed at a passenger side door.
Supplied to The audio signal SLL is supplied to, for example, a low-frequency left speaker LL provided on the rear left side of the rear seat. The audio signal SHR is supplied to, for example, a high-range right speaker HR installed on the right side of a front console in an automobile. The audio signal SMR is supplied to, for example, a middle-range right speaker MR installed at a driver's seat side door. The audio signal SLR is supplied to, for example, a low-frequency right speaker LR installed on the rear right side of the rear seat.

The processing in the preamplifier unit 2 is executed under the control of the control unit 1. The control unit 1 is constituted by a microcomputer. The ROM 5 and the nonvolatile memory 6 store programs, setting data, processing coefficients, and the like, and the control unit 1 executes necessary control operations using these pieces of information. The control unit 1 further monitors a user operation using the operation unit 3 and performs processing corresponding to the operation, and performs display control on the display unit 4 and the like. The operation unit 3 is provided with, for example, a menu key, a mode setting key, a numerical value input key, an enter key, a pointer movement key, and the like. You.

The control unit 1 displays on the display unit 4 a display required for a power amplifier unit of the audio system, a display for setting a listening point for time alignment adjustment, and the like. Further, a temperature sensor 7 is provided to detect the temperature in the vehicle interior and supply the temperature value to the control unit 1. The ROM 5 holds table data of sound speeds corresponding to various temperature values in a predetermined number of steps. Therefore, the control unit 1 can determine the sound speed according to the current temperature inside the vehicle by referring to the table data in the ROM 5 according to the current temperature supplied from the temperature sensor 7.

FIG. 2 shows the internal configuration of the preamplifier unit 2. The audio signal SIN is first converted in the preamplifier unit 2 into digital data in the A / D converter 21. And DSP22 (DIGI) as digital audio data
TAL SIGNAL PROCESSER). The DSP 22 performs necessary filter processing such as processing as a crossover network, equalizing processing, and the like on the audio signal. For the audio signal on which these required processes have been performed, D
-Perform delay processing for each channel for time alignment or the like using the RAM 23. That is, by adjusting the write / read timing in the D-RAM 23, a required delay time specified by the control unit 1 is given to the audio signal of each channel. For example, the delay amount is given from the control unit 1 as the number of samples, and the timing of writing to the D-RAM 23 is delayed by the sample clock timing corresponding to the number of samples.

The digital audio signals for each channel are converted into analog audio signals by the D / A converters 24 to 29, respectively, and subjected to amplification and volume adjustment processing as a power amplifier unit by the volume adjustment unit 30. Then, audio signals SHL, SML, SLL, SHR, SMR, SLR of each channel output from the preamplifier unit 2
Is supplied to six speaker units.

2. Initial setting An initial setting operation performed for the time alignment function in such a sound processing apparatus will be described. As described above, the time alignment function is a listening point that is not actually equidistant from a plurality of speaker units. This is a function for giving a required delay to each sound so that the sound (sound wave) of each channel at the same timing reaches the listening point simultaneously.

In order to realize this function, it is necessary to know the difference in the distance from each speaker unit to the listening point. For this purpose, it is necessary for the user to make predetermined settings in advance. The setting may be such that the distance from a certain listening point to each speaker unit can be grasped by the control unit 1.

Various methods can be considered as the initial setting method. As the most basic method, a user sets a listening point and measures a distance from the listening point to each speaker unit. Then, the measured values (six measured values in the case of six channels as in this example) are input from the operation unit 3. As a result, the control unit 1 can grasp the distance difference from each speaker unit to the listening point, and can calculate the necessary delay time for each channel.

However, in such a system, every time the listening point is changed, measurement and distance input must be repeated. Therefore, as an initial setting, the control unit 1 stores in advance the coordinates of the space corresponding to the interior of the vehicle and the coordinate values corresponding to the positions of the speaker units, so that the listening point can be set later and easily changed. It is also conceivable to do this.

That is, as an initial setting, the user inputs the vertical and horizontal sizes of the space in the vehicle interior, and the control unit 1 sets the vehicle interior space of that size as an xy coordinate system. May input the positions of the six speakers so that the control unit 1 can hold the positions of the speakers as coordinate values. Referring to the image of the cabin in FIG. 4, the initial settings are x,
y size and each speaker unit HL, ML, LL,
The positions of HR, MR, and LR are input, and the control unit sets the coordinates of each speaker unit in the xy coordinate system as follows: position of speaker unit HL = (HLx, HLy) Position of speaker unit ML = (MLx, MLy) Speaker The position of the unit LL = (LLx, LLy) The position of the speaker unit HR = (HRx, HRy) The position of the speaker unit MR = (MRx, MRy) The position of the speaker unit LR = (LRx, LRy) Become.

Although various types of user operation methods for the initial setting can be considered as an actual operation procedure, three types of initial setting operation examples will be described here.

First, the first initial setting method is a method in which user operation is the simplest. The size of the cabin space is determined by the type of vehicle. In addition, the speaker mounting position is fixed in most cases (that is, it depends on the vehicle type). Therefore, ROM5
The xy size and the coordinate value of each speaker position are stored in a table format corresponding to the data of the vehicle type (manufacturer name, vehicle name, year model) in the nonvolatile memory 6 or the like. When the initial setting operation is started, the control unit 1 displays a list of vehicle type data on the display unit 4 and prompts the user to perform a selection operation. At this time, for example, the display may be advanced to a maker name selection screen, a car name selection screen, a year selection screen, and a menu hierarchy type to prompt the user to make a selection sequentially. When the user performs a selection operation on the selection menu display using the operation unit 3, the control unit 1 knows the type of the vehicle equipped with the audio system, and thus refers to the table data corresponding to the type of the vehicle. By doing, the cabin size x, y
And the coordinate value of each speaker unit can be grasped. The control unit 1 stores the xy value and the coordinates of the speaker unit position in, for example, a predetermined area of the nonvolatile memory 6 (or may store the selected vehicle type information, or the number or address on the data table). With such an operation, the controller 1 can grasp the arrangement state as shown in FIG. 4 as coordinates, and the initial setting ends.

In the second initial setting method, the position of the speaker unit is input by the user himself. The size of the cabin space is determined by the type of vehicle, but the speaker mounting position can be changed or added by the user himself. Therefore, the x and y values as the cabin space are stored in the ROM 5 or the like corresponding to various vehicle types, as in the first method, and the user selects the vehicle type by a menu selection method. , The control unit 1 can grasp the x and y values.

Subsequently, a display for inputting the position of each speaker unit is displayed on the display unit 1, and the user inputs numerical values actually measured in accordance with the display. When measuring, for example, specify a specific measurement starting point (in the instruction manual, etc.)
Instruct the user. For example, as the front right end in the vehicle interior, the user measures the size on the x and y axes from the starting position to the speaker position and inputs the value. The control unit 1 stores the measured value in the non-volatile memory 6 as the measured value is input to each speaker unit. With such an operation, the controller 1 can grasp the arrangement state as shown in FIG. 4 as coordinates, and the initial setting ends.

As a third initial setting method, the user measures all the x and y values and the speaker position as the vehicle interior space, and inputs the measured values. That is, first, the vertical and horizontal sizes of the cabin space are measured and input, and then the position of each speaker unit is measured and input as in the above-described second initialization method. The control unit 1
As the x and y values as the vehicle interior space and the actually measured values are input to each speaker unit, they are stored in the nonvolatile memory 6. With such an operation, the controller 1 can grasp the arrangement state as shown in FIG. 4 as coordinates, and the initial setting ends. For example, if the size of the cabin space is described in an automobile catalog or the like, the user may input the described size as x and y sizes without actually measuring the size.

For example, after the initial setting is performed by these operation methods, the listening point for actually performing the time alignment function is set or the set listening point is changed as needed. At the time of setting operation of a listening point for time alignment, for example, the control unit 1 displays an image of an image as shown in FIG. The user performs a pointer moving operation on the operation unit 3 while watching the screen of the display unit 4, moves the pointer P to a position desired to be set as a listening point, and performs an enter operation. Then, the control unit calculates the coordinate value (Px, Py) of the pointer P as the listening point
Then, the distance between the listening point and each speaker unit can be calculated from the coordinate values of each speaker unit described above, whereby the delay time required for the time alignment operation can be obtained. By giving the obtained delay time to the signal of each channel in the preamplifier unit 2, a time alignment operation is realized.

3. Time alignment operation The actual time alignment operation will be described. In the time alignment operation of this example, the delay time of each channel is adjusted according to not only the setting change (the speaker arrangement change and the listening point change) as described in the above initial setting but also the temperature condition in the vehicle. Thus, an optimum listening environment is always obtained at the listening point.

FIG. 3 shows the processing of the control unit 1 during the time alignment operation. This flowchart is a process that functions during execution of the time alignment operation. In a state where a predetermined delay time is given to the audio signal of each channel, the control unit 1 monitors whether or not a setting change operation has been performed in step F101. In step F102, the temperature information from the temperature sensor 7 is monitored to determine whether there has been a temperature change.

If there is a setting change such as a change of the listening point, the delay time of each channel must be changed according to the positional relationship between the new listening point and each speaker unit.
Going to 04 or less, delay time control is performed. Further, in this example, even when a temperature change is detected, the process proceeds to step F104 and the following in consideration of the fact that the sound speed changes with temperature. However, at this time, in step F103, the value of the sound speed corresponding to the current temperature is searched in the data table stored in the ROM 5 and set as the sound speed value VC used for the calculation.

Steps F104, F105, F106
Is a process for setting the delay time of the signal of each channel for the time alignment operation. When the setting of the listening point or the like or the change in the sound velocity VC due to the temperature change is performed, the control unit 1 firstly performs step F104.
Then, a delay time to be given to the audio signal of each channel according to the setting situation and the temperature at that time is calculated. As described in the above description of the initial setting, when a method in which the control unit 6 calculates the distance between the listening point and each speaker unit using the coordinate system is adopted, first, at the time of calculating the delay time, From the listening point (Px, Py) according to the setting situation, each speaker unit HL, ML,
The respective distances to LL, HR, MR, and LR will be calculated. For example, when the position of the pointer P on the driver's seat in FIG. 4 is set as the listening point, the distances dHL, dML, dLL, dHR, dM in the figure are set.
Calculate R and dLR.

As described above, each speaker unit HL,
Coordinate values corresponding to the positions of ML, LL, HR, MR, and LR are represented by HL = (HLx, HLy) and ML = (MLx, ML
y), LL = (LLx, LLy), HR = (HRx, H
Ry), MR = (MRx, MRy), LR = (LRx,
LRy), distances dHL, dML, dLL, dH
R, dMR, and dLR (distance as an absolute value) can be obtained as in the following (Equation 1).

[0033]

(Equation 1)

If there is no change in the setting of the listening point or the like and the process proceeds to step F104 due to a change in temperature, it is particularly necessary to newly calculate a distance by storing the values of each distance in the setting conditions up to that time. There is no. Further, when an initial setting method in which the user measures and inputs the distance from the listening point to each speaker unit is executed, the above distance calculation is naturally unnecessary.

With the distance between the listening point and each speaker unit being grasped, the delay time DT to be actually given to the signal of each channel is calculated. In order to calculate the delay time DT for each channel, first, the distances dHL, dML, dLL, dHR, dMR, dL
Search for the maximum value in R.

The maximum value among the calculated six distances is dM
Assuming that AX (absolute value) and dd (absolute value) is the distance of the channel for which the delay time is to be obtained, this (dMAX-d
If the value of d), that is, the difference in distance from the longest distance channel, is divided by the sound velocity VC, the delay time DT to be delayed for that channel for time alignment
Is required. That is, the delay time DT is

(Equation 2) Is required.

More specifically, in the case of the example of FIG. 4, since the distance dLL to the speaker unit LL is the longest distance, the maximum value dMAX = dLL. Then, the delay times DTHL, DTML, DTLL, and DTHL for each of the speaker units HL, ML, LL, HR, MR, and LR.
DTHR, DTMR, and DTLR are calculated as follows.

[0038]

(Equation 3)

As described above, the delay time DT (DTHL, DTML, DTL) to be given to the audio signal of each channel
L, DTHR, DTMR, DTLR)
Next, in step F105, the delay time of each channel is set to D
The value is converted into the number of delay samples as a value for controlling the amount of delay in SP22. The number of delay samples SP is A
Since the sampling frequency may be multiplied by the value of the sampling frequency in the / D converter 21, if the sampling frequency is Fs, the number of delay samples SP is

(Equation 4) Is required.

The number of delay samples applied to the audio signal SHL of the channel of the speaker unit HL is SPHL, the number of delay samples applied to the audio signal SML of the channel of the speaker unit ML is SPML, and the number of delay samples applied to the audio signal SLL of the channel of the speaker unit LL. Number S
The number of delay samples given to the audio signal SHR of the channel of the PLL and speaker unit HR is SPHR, the number of delay samples given to the audio signal SMR of the channel of the speaker unit MR is SPMR, and the number of delay samples given to the audio signal SLR of the channel of the speaker unit LR SPL
Specifically speaking as R, the number of each delayed sample is

(Equation 5) Is calculated as

The number of delay samples of each channel calculated in this way is set in the DSP 22 in step F106, and the DSP 22 delays the signal of each channel according to the number of delay samples set for the audio signal of each channel. Output. As a result, the time alignment function becomes effective, and in the example of FIG. 4, a state where all the speaker units are pseudo-equidistant in the driver's seat is realized.

That is, the delay time is set to zero for the signal SLL of the channel of the speaker unit LL which is the longest distance to the listening point, but for the other channels, the distances dHL, dML, and dHL from the speaker unit to the listening point are set. dHR, dMR, dLR
Are given a delay time corresponding to a distance shorter than the distance dLL, and the voices at the same timing reach the user sitting in the driver's seat at the same timing in the six channels.

In the process of calculating the delay time DT in step F104, the sound velocity value VC corresponding to the current temperature set in step F103 is used. Delay is given to each channel. That is, the optimum time alignment operation is realized regardless of the temperature condition in the automobile when the audio system is used (even in an environment where the sound speed varies). Further, even if there is no change in the setting, even if a temperature change occurs, the processing from step F104 onward functions as a delay time correction operation for time alignment. The alignment function will always be kept in an optimal state.

In the above example, a 6-channel audio system has been described. However, the present invention is not limited to the number of channels such as 2 channels and 4 channels and the multiway system, but may be a system using speaker units installed at a plurality of different positions. If so, the invention can be applied in exactly the same way. In the above example, the sound speed value is determined by providing a data table in which the temperature and the sound speed are associated with each other. However, a method in which the sound speed is obtained by calculation using the temperature value may be adopted.

The present invention can be applied not only to an audio system mounted on a vehicle but also to an audio system used in a specific acoustic space. For example, it is useful as an audio system installed in a room in a house.

[0046]

As described above, the sound processing apparatus according to the present invention changes the sound velocity value used for the calculation for setting the delay time according to the temperature condition, and sets the optimum delay time. Therefore, there is an effect that an optimal time alignment function can always be realized without error. In particular, it is suitable as an acoustic processing device in an environment where temperature changes are severe such as in an automobile.

[Brief description of the drawings]

FIG. 1 is a block diagram of a sound processing apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a preamplifier unit of the sound processing device according to the embodiment;

FIG. 3 is a flowchart of a process during a time alignment operation of the sound processing apparatus according to the embodiment;

FIG. 4 is an explanatory diagram of a time alignment operation according to the embodiment.

[Explanation of symbols]

1 control section, 2 preamplifier unit, 3 operation section, 4
Display unit, 5 ROM, 6 non-volatile RAM, 21 A
/ D converter, 22 DSP 23 D-RAM, 24-
29 D / A converter, 30-35 volume adjustment unit, P pointer, HL high-range left speaker, HR high-range right speaker,
ML middle left speaker, MR middle right speaker, LL
Low frequency left speaker, LR low frequency right speaker,

Claims (3)

[Claims] An audio processing unit capable of performing at least delay processing on each of audio signals of each channel supplied to a plurality of speaker units, and detecting a temperature of an acoustic space formed by the plurality of speaker units. Temperature detecting means, a distance between the set listening point and each speaker unit, and a sound speed value corresponding to the current temperature detected by the temperature detecting means, the sound signal of each channel by the sound processing means. And a delay control means for setting and controlling a delay time given to the sound processing apparatus. 2. The delay control means holds a data table in which each temperature value and sound velocity value data are associated with each other, and refers to the data table for a temperature value detected by the temperature detection means, and The sound processing apparatus according to claim 1, wherein a sound velocity value according to the temperature is determined. 3. The delay processing means according to claim 1, wherein when the temperature value detected by said temperature detecting means changes, the sound processing means uses the sound speed value according to the new temperature value to output the sound of each channel. 2. The sound processing apparatus according to claim 1, wherein setting control of a delay time given to the signal is performed.