JP6912967B2 - Sound field correction data calculation device and sound field correction device - Google Patents

Description

The present invention relates to a sound field correction data calculation device and a sound field correction device.

In general, the sound output from a speaker has a specific frequency band that is attenuated more than other frequency bands when it is reflected by, for example, a wall of a room or a chair, or a wall of a room before it reaches the user's ear. The frequency characteristics change when the reflected waves reflected by a chair or the like interfere with each other and strengthen or weaken each other. By changing the frequency characteristics of the sound output from the speaker, the sound field generated by the sound output from the speaker changes, and the frequency characteristics of the sound reaching the user's ear also change. For example, if the sound field is such that the sound whose mid-low range is attenuated more than other frequency bands reaches the user's ear, it becomes difficult for the user to hear, for example, the mid-low range (vocal, etc.).

Therefore, there is known a sound field correction system capable of correcting the sound field to be close to the original sound by correcting the frequency characteristic of the sound output from the speaker. In this type of sound field correction system, the frequency is such that the sound recorded on the recording medium (for example, a sound having a flat frequency characteristic) becomes a sound field that can be heard by the user's ear as a sound having a flat frequency characteristic. Sound with corrected characteristics is output from the speaker. That is, the sound field correction is performed so that the sound whose frequency characteristics are faithfully reproduced (in this example, the sound having the flat frequency characteristics) reaches the user's ear. For example, Patent Document 1 describes a specific configuration of this type of sound field correction system.

Patent Document 1 describes a sound field correction system installed in a vehicle. This sound field correction system includes a sound field correction device and a speaker connected to the sound field correction device. The sound field correction device provided in this sound field correction system has a function of calculating sound field correction data for correcting the frequency characteristics of the sound output from the speaker (in other words, this sound field correction device is , It has a built-in sound field correction data calculation device that calculates sound field correction data.) This sound field correction device corrects the sound field generated by the sound output from the speaker by correcting the frequency characteristics of the sound output from the speaker based on the sound field correction data calculated by the function.

Specifically, the sound field correction device described in Patent Document 1 collects sounds output from a plurality of speakers installed in a vehicle by a microphone set in the vehicle interior. This sound field correction device calculates the frequency characteristics of the sound signal obtained by collecting the sound by the microphone, and calculates the sound field correction data (for example, the gain value for each frequency band) for each speaker based on the calculation result. This sound field correction device corrects the sound field in the vehicle interior by correcting the frequency characteristics of the sound output from each speaker based on the calculated sound field correction data.

JP-A-2007-189317

As described above, in the sound field correction system described in Patent Document 1, the sound output from the speaker is picked up by using the microphone connected to the sound field correction device, and the sound obtained by the sound pick-up by the microphone is picked up. It is possible to calculate the sound field correction data for the first time by calculating the frequency characteristics of the signal. That is, in the configuration described in Patent Document 1, the sound field correction data cannot be calculated unless the sound output from the speaker is collected by using an independent microphone as a device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to calculate sound field correction data even though the sound is not collected by using an independent microphone as a device. It is an object of the present invention to provide a possible sound field correction data calculation device and a sound field correction device having such a sound field correction data calculation device.

The sound field correction data calculation device according to the embodiment of the present invention corrects the sound field generated by the sound output from the speaker by correcting the frequency characteristic of the sound output from the speaker. It is a device that calculates, and an output unit that outputs a predetermined sound from the speaker, and a signal generated by the generated countercurrent force when a countercurrent force is generated in the speaker due to the speaker receiving a reflected wave of the predetermined sound. It includes a detection unit for detection, a calculation unit for calculating the frequency characteristics of the detection signal detected by the detection unit, and a calculation unit for calculating sound field correction data based on the frequency characteristics of the detection signal calculated by the calculation unit. ..

Further, in one embodiment of the present invention, the output unit may be configured to output a predetermined sound from the speaker for a certain period of time. In this case, when the back electromotive force is generated by the speaker receiving the reflected wave of the predetermined sound after the output of the predetermined sound from the speaker is stopped, the detection unit detects the signal generated by the generated back electromotive force. ..

Further, in one embodiment of the present invention, the output unit may be configured to intermittently output a predetermined sound from the speaker. In this case, when the back electromotive force is generated by the speaker receiving the reflected wave of the predetermined sound during each period when the speaker does not output the predetermined sound, the detection unit outputs a signal generated by the generated back electromotive force. To detect. In addition, the calculation unit calculates the frequency characteristics of the detection signal of each period detected by the detection unit, and averages the frequency characteristics of the calculated detection signals of each period. Further, the calculation unit calculates the sound field correction data based on the frequency characteristics of the averaged detection signal.

Further, the sound field correction data calculation device according to the embodiment of the present invention may be further provided with a storage unit for storing predetermined initial correction data in advance. In this case, the output unit outputs a predetermined sound corrected by the initial correction data from the speaker.

Further, the sound field correction data calculation device according to the embodiment of the present invention may be further provided with an amplification unit that amplifies the signal generated by the back electromotive force generated. In this case, the detection unit detects the signal amplified by the amplification unit. The calculation unit calculates the frequency characteristics of the detection signal detected by the detection unit. The calculation unit calculates the sound field correction data based on the frequency characteristics of the detection signal calculated by the calculation unit and the frequency characteristics of the reference.

Further, in one embodiment of the present invention, the speaker is installed, for example, in the headrest of a seat in a vehicle.

Further, the sound field correction device according to the embodiment of the present invention is a speaker based on the sound field correction data calculation device according to any one of the above and the sound field correction data calculated by the sound field correction data calculation device. It is provided with a correction unit that corrects the sound field generated by the sound output from the speaker by correcting the frequency characteristic of the sound output from the speaker.

According to one embodiment of the present invention, a sound field correction data calculation device capable of calculating sound field correction data even though it is configured not to collect sound using an independent microphone as a device, and such a sound field correction data calculation device. A sound field correction device having a sound field correction data calculation device is provided.

It is a figure which shows typically the vehicle which installed the sound field correction system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the sound field correction system which concerns on one Embodiment of this invention. It is a figure which shows the sound field correction data calculation process executed by the sound field correction apparatus provided in the sound field correction system which concerns on one Embodiment of this invention by the flowchart. It is a figure for demonstrating the effect of the sound field correction by the sound field correction data calculated by the sound field correction data calculation process of FIG. It is a figure which shows typically the vehicle which installed the sound field correction system which concerns on another embodiment of this invention.

Hereinafter, the sound field correction system according to the embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing a user's vehicle A in which the sound field correction system 1 according to the embodiment of the present invention is installed. In FIG. 1, a part of the body of the vehicle A is shown transparent so that the sound field correction system 1 installed in the vehicle can be seen.

As shown in FIG. 1, the sound field correction system 1 has a sound field correction device 2 and speakers SP _FR , SP _FL , SP _RR , and SP _RL connected to the sound field correction device 2. The sound field correction device 2 is installed on a dashboard, for example, and has a function of calculating sound field correction data for correcting the frequency characteristics of sounds output from _{each speaker SP FR} , SP _FL , SP _RR , and SP _RL. (In other words, the sound field correction device 2 has a built-in sound field correction data calculation device for calculating the sound field correction data). Speakers SP _FR , SP _FL , SP _RR , and SP _RL are the driver side door D _FR , the passenger side door D _FL , the rear seat right door D _RR , and the rear seat left door D, respectively. _It is installed in the RL.

The sound field correction device 2 outputs the audio signal stored in the recording medium RM to the speakers SP _FR , SP _FL , SP _RR , and SP _RL . As a result, the music or the like recorded on the recording medium RM is reproduced. The recording medium RM is, for example, a disk medium such as a CD (Compact Disc) or SACD (Super Audio CD), or a storage medium such as an HDD (Hard Disk Drive) or USB (Universal Serial Bus).

FIG. 2 is a block diagram showing a configuration of a sound field correction system 1 according to an embodiment of the present invention. As shown in FIG. 2, the sound field correction device 2 includes a microcomputer 12, a DSP (Digital Signal Processor) 14, an output circuit 16, an operation unit 18, a test signal generation circuit 20, an amplifier circuit 22 _FR , 22 _FL , 22. It is equipped with _RR and 22 _RL. Note that FIG. 2 illustrates the main components necessary for the description of the present embodiment, and some components such as a housing, which is a general component of the sound field correction device, are shown. It is omitted as appropriate.

Further, in the present embodiment, for convenience, it is assumed that there is no signal delay between the components of the sound field correction device 2. Further, when the components with subscripts ( _FR , _FL , _RR , _RL ) are described separately, the subscripts such as "speaker SP _FR , SP _FL , SP _RR , SP _RL " are used. If the explanation is not made separately, the subscript is not added, for example, "speaker SP".

The microcomputer 12 includes a CPU (Central Processing Unit) 122, a ROM (Read Only Memory) 124 for storing a control program executed by the CPU 122, and a RAM (Random Access) for temporarily storing various data necessary for executing the control program. It has a Memory) 126 and a flash memory 128. The ROM 124 stores a frequency characteristic calculation program 124A and a sound field correction data calculation program 124B for executing the sound field correction data calculation process described later.

An audio signal read from the recording medium RM by a reading device such as an optical pickup is input to the DSP 14. The DSP 14 performs various signal processing such as equalizing on the audio signal read from the recording medium RM, and outputs the audio signal to the output circuit 16.

The equalizing is performed by the equalizer unit 142 included in the DSP 14. The equalizer unit 142 includes, for example, an IIR (Infinite Impulse Response) filter circuit. The equalizer unit 142 performs level correction (that is, equalizing) for each frequency band of the audio signal by applying a filter coefficient to the audio signal read from the recording medium RM. The filter coefficient may be, for example, one stored in advance in the flash memory 128 or one calculated by executing the sound field correction data calculation process described later (filter coefficient FC described later).

The output circuit 16 DA-converts and amplifies the audio signal input from the DSP 14, and outputs the audio signal to each speaker SP.

Each speaker SP is provided with a magnetic circuit M (for example, a combination of a magnet and a yoke), a voice coil C, and a cone-type diaphragm V. In FIG. 2, for convenience, the symbols M, C, and V are attached only to the magnetic circuit, voice coil, and cone type diaphragm V provided in the _{speaker SP FR, respectively.}

The voice coil C is placed in a magnetic field generated by the magnetic circuit M. Therefore, when the audio signal input to the speaker SP flows through the voice coil C, the voice coil C vibrates according to Fleming's left-hand rule. When the voice coil C vibrates, the cone type diaphragm V to which the voice coil C is attached also vibrates. As the cone-shaped diaphragm V vibrates, sound waves corresponding to the audio signal are output from each speaker SP. As a result, the user can listen to the music or the like recorded on the recording medium RM.

Next, the sound field correction data calculation process for calculating the sound field correction data will be described. By correcting the frequency characteristics of the sound output from each speaker SP based on the sound field correction data calculated in this process, the sound field in the vehicle interior generated by the sound output from each speaker SP is corrected. ..

As shown in FIG. 2, a microphone is not connected to the sound field correction device 2. Here, it is known that when the voice coil in the speaker vibrates, the magnetic flux applied to the voice coil changes, and the counter electromotive force corresponding to the change in the magnetic flux flows into the boil coil and flows into the circuit connected to the speaker. ing. In the present embodiment, the sound field correction data is calculated by using the above-mentioned counter electromotive force generated in the speaker instead of using an independent microphone as a device.

FIG. 3 is a flowchart showing a sound field correction data calculation process executed by the sound field correction device 2. For example, when the user performs a predetermined operation instructing the operation unit 18 to calculate the sound field correction data, the execution of the sound field correction data calculation process shown in FIG. 3 is started.

As shown in FIG. 3, when the execution of the sound field correction data calculation process is started, the microcomputer 12 generates the sound field correction data (filter coefficient FC described later) by executing the past sound field correction data calculation process. It is determined whether or not the data is stored in the flash memory 128 (step S11).

When the sound field correction data is stored in the flash memory 128 (step S11: YES), the microcomputer 12 performs a reset process (erasing the sound field correction data) (step S12).

The microprocessor 12 instructs the test signal generation circuit 20 to generate a predetermined test signal. The test signal generation circuit 20 receives a command from the microcomputer 12 to generate a predetermined test signal, and outputs the generated test signal to the DSP 14. The test signal generated by the test signal generation circuit 20 is, for example, pink noise or white noise.

The equalizer unit 142 of the DSP 14 outputs the test signals output to _{the speakers SP FR} , SP _FL , SP _RR , and SP _{RL via the output circuit 16 with the initial filter coefficients I FR} , I _FL , I _RR , and I _RL , respectively. Correct (step S13). Hereinafter, for convenience, the correction of the test signal by the initial filter coefficient I will be referred to as “initial correction”. Details of the initial correction will be described later.

The DSP 14 intermittently outputs the test signal initially corrected by the equalizer unit 142 to the output circuit 16 (at a predetermined cycle in this embodiment). As a result, the test sound is output from each speaker SP via the output circuit 16 at a predetermined cycle (step S14).

Since the passenger compartment is not an anechoic chamber, the test sound output from each speaker SP is reflected in the passenger compartment. Therefore, the reflected wave of the test sound output by itself and the direct wave and the reflected wave of the test sound output from the other speakers (three speakers other than the speaker) SP reach each speaker SP. When the cone-type diaphragm V vibrates due to these sound waves that have reached (referred to as “arrival wave” for convenience), the voice coil C attached to the cone-type diaphragm V vibrates together with the cone-type diaphragm V. The voice coil C vibrates and the magnetic flux applied to the voice coil C changes, so that a counter electromotive force is generated according to the change in the magnetic flux.

Depending on the layout of the seat and the speaker SP, the shape of the vehicle interior, and the like, the direct sound from the other speaker SP may not reach (for example, blocked by the seat). In this case, only the reflected wave of each test sound output from itself and the other three speaker SPs reaches each speaker SP.

When a counter electromotive force is generated in the speaker SP, a signal generated by the generated counter electromotive force (a voltage signal whose level is changed by the counter electromotive force) is output from the speaker SP to the output circuit 16 side. Here, during the output period during which the test sound is output from the speaker SP, counter electromotive force is mainly generated from the test signal input from the output circuit 16 to the voice coil C. On the other hand, during the non-output period when the test sound is not output from the speaker SP (strictly speaking, during the non-output period after the vibration of the voice coil C due to the test signal input to the voice coil C disappears), the arrival wave is substantially reached. Only the counter electromotive force derived from is generated.

Therefore, during the output period of the test sound, the signal generated by the counter electromotive force, which is mainly derived from the test signal input from the output circuit 16 to the voice coil C, is output from the speaker SP to the output circuit 16 side. Further, during the non-output period of the test sound, only the signal generated by the counter electromotive force, which is substantially derived from the arrival wave, is output from the speaker SP to the output circuit 16 side.

_{Hereinafter, for convenience, the signals generated by the back electromotive force output from the speakers SP FR} , SP _FL , SP _RR , and SP _RL to the output circuit 16 side during the output period of the test sound are referred to as "back electromotive force derived from the input signal". Power signals S _FR , S _FL , S _RR , S _RL ". In addition, during the non-output period of the test sound, the _{signals generated by the counter electromotive force output from the speakers SP FR} , SP _FL , SP _RR , and SP _RL to the output circuit 16 side are each "counter electromotive force derived from the arrival wave. signal _{S 'FR, S' FL,} S 'RR, S' referred to as _RL ".

Each amplifier circuit 22 includes an AGC (Automatic Gain Control) circuit. The input terminals of the amplifier circuits 22 _FR , 22 _FL , 22 _RR , and 22 _{RL are the branch points P FR} , P _FL , and P _{RR between the speakers SP FR} , SP _FL , SP _RR , SP _RL and the output circuit 16, respectively. , _Is connected to PRL. Therefore, the signal generated by the counter electromotive force generated in each speaker SP is input to each amplifier circuit 22 via the branch point P.

Here, the arrival wave that reaches the speaker SP is the sound (sound wave) itself that can be heard at the installation position of the speaker SP. Therefore, in the present embodiment, the sound field correction data is calculated by using the back electromotive force signal S'generated in the speaker SP according to the arrival wave.

However, the counter electromotive force signal S'derived from the arrival wave is not a signal input from the output circuit 16 to the voice coil C, but is a weak signal generated as the voice coil C vibrates due to sound waves received from the outside. It is a signal. If the level remains weak, it is difficult to calculate the sound field correction data using the counter electromotive force signal S'derived from the arrival wave. Further, the strength of the arrival wave reaching the speaker SP varies from vehicle to vehicle due to the influence of the layout of the seat and the speaker SP, the shape of the vehicle interior, and the like. As a result, the counter electromotive force signal S'derived from the arrival wave also varies from vehicle to vehicle. Further, the arrival wave arrives at each speaker SP via a different path. Therefore, the strength of the reaching wave varies depending on the speaker SP. Therefore, the counter electromotive force signal S'derived from the arrival wave is amplified to a certain level necessary for executing the sound field correction data calculation process regardless of the input level to the amplifier circuit by the amplifier circuit 22 provided with the AGC circuit. (Step S15). That is, the counter electromotive force signal _{S 'FR, S' FL,} S 'RR, S' RL is aligned at a constant level required for executing the sound field correction data calculation process.

The counter electromotive force signal S'from the arrival wave amplified by each amplifier circuit 22 is input to the microcomputer 12. More specifically, the microcomputer 12 is input with the countercurrent power signal S'derived from the arrival wave during the non-output period of the test sound, while the countercurrent power signal derived from the input signal is input during the output period of the test sound. The signal S is input.

The microcomputer 12 calculates the frequency characteristic of the counter electromotive force signal S'derived from the arrival wave by executing the frequency characteristic calculation program 124A stored in the ROM 124 (step S16).

Specifically, the microcomputer 12 detects and buffers only the countercurrent power signal S'from the arrival wave input at a predetermined cycle (during each non-output period of the test sound) based on the input timing. Then, the frequency characteristics are calculated only for the buffered back electromotive force signal S'(detection signal). The calculation of the frequency characteristic is performed using, for example, FFT (Fast Fourier Transform).

In the present embodiment, by outputting the test sound from the speaker SP at a predetermined cycle, the counter electromotive force signal S derived from the input signal and the counter electromotive force signal S'derived from the arrival wave are transmitted to the microcomputer 12 on the time axis. It is designed to be input separately. That is, when the back electromotive force signal S and the back electromotive force signal S'are separated and input to the microcomputer 12, a complicated separation circuit is not required.

The microcomputer 12 is then obtained by the above calculation, averaging the frequency characteristic of the counter electromotive force signal S _'FR of each non-output period. The microcomputer 12 similarly averages the frequency characteristics of the remaining back electromotive force signals _S'FL , _S'RR , and _S'RL.

Reference data indicating a predetermined reference characteristic is stored in the flash memory 128. This reference characteristic shows the frequency characteristic of an ideal (no distortion or noise) test sound.

The microcomputer 12 calculates the sound field correction data by executing the sound field correction data calculation program 124B stored in the ROM 124 (step S17).

Specifically, the microcomputer 12 compares the frequency characteristic and the reference characteristic of the counter electromotive force signal S _'FR, averaged in step S16, the filter coefficient FC _FR corresponding to the difference between both the frequency characteristic , Calculated as sound field correction data. The microcomputer 12 performs comparison with similarly reference characteristics in frequency characteristics of the rest of the reverse electromotive force signal _{S 'FL, S' RR,} S 'RL, calculating filter coefficients _{FC FL,} FC RR, the _{FC RL} .. The microcomputer 12 stores each calculated filter coefficient FC in the flash memory 128.

Here, in general, the larger the difference between the frequency characteristic and the reference characteristic of the test sound (hereinafter referred to as "measured sound") picked up at the sound receiving point (in this embodiment, the installation position of the speaker SP), the more tapped. Without using a large number of filter circuits, it is difficult to calculate a highly accurate filter coefficient (that is, to correct the frequency characteristic of the measured sound to the same extent as the reference characteristic).

Therefore, in the present embodiment, the frequency characteristic of the measurement sound (that is, the arrival wave reaching the speaker SP) measured in the user's vehicle A is set to be close to the reference characteristic stored in the flash memory 128 to some extent. In step S11, the test signal is initially corrected by the initial filter coefficient I (initial correction data).

The initial filter coefficient I is created by the manufacturer, for example, before the sound field correction device 2 is shipped. Illustratively, in each of a plurality of types of vehicles (for example, a sedan equipped with four speakers, a sedan equipped with eight speakers, a minivan equipped with four speakers, etc.), a microphone set in the vehicle was used. The sound field measurement is performed, and the initial filter coefficient I is calculated based on the result of the sound field measurement. As an example, a microphone is set near the installation position of each speaker, sound field measurement is performed, and an initial filter coefficient I corresponding to each setting position (installation position of each speaker) is calculated. Hereinafter, the vehicle used by the manufacturer for calculating the initial filter coefficient I will be referred to as a “sample vehicle” for convenience. That is, on the manufacturer side, the initial filter coefficient I is calculated for a plurality of types of sample vehicles by a well-known method using a microphone exemplified in Patent Document 1.

The flash memory 128 stores, for example, an initial filter coefficient I calculated by using a sample vehicle of the same type as the user's vehicle A among a plurality of types of sample vehicles before the sound field correction device 2 is shipped. For example, when the vehicle A is a sedan in the present embodiment, a total of four speakers are provided on each door portion of the driver seat side door portion, the passenger seat side door portion, the rear seat right door portion, and the rear seat left door portion. The sample vehicle of the installed sedan will be the same type as vehicle A.

The sample vehicle of the same type as the user's vehicle A is relatively similar to the vehicle A in the layout of the seats and speakers, the shape of the vehicle interior, and the like. Therefore, in the vehicle A, when the test sound is output from the speaker SP, it repeatedly reflects in the same path as in the sample vehicle, and reaches the speaker SP while being attenuated or causing phase interference. Therefore, by pre-correcting the test sound output from the speaker SP with the initial filter coefficient I created using the sample vehicle, the frequency characteristics of the arrival wave reaching each speaker SP can be brought closer to the reference characteristics to some extent. Can be done. Since the difference between the frequency characteristic of the arrival wave and the reference characteristic can be suppressed, the number of taps required to calculate the filter coefficient FC can be suppressed.

FIG. 4A shows the frequency characteristic of the counter electromotive force signal S'from the arrival wave calculated in step S16 of FIG. 3 (that is, the frequency of the measured sound measured when there is no correction by the filter coefficient FC). Characteristics) will be illustrated. Further, FIG. 4B illustrates the filter characteristics realized by the filter coefficient FC calculated in step S17 of FIG. Further, FIG. 4C illustrates the frequency characteristics of the measured sound measured when the test sound is corrected by the filter coefficient FC (and the initial filter coefficient I). In each of FIGS. 4A to 4C, the vertical axis represents the gain (unit: dB), and the horizontal axis represents the frequency (unit: Hz). In the example of FIG. 4, pink noise is used as the test sound.

When there is no correction by the filter coefficient FC, as shown in FIG. 4A, the frequency characteristic of the measured sound is ideal due to, for example, the generation of dips due to the interference between the arrival waves arriving at the speaker SP via different paths. Distorted against typical pink noise. On the other hand, when there is correction by the filter coefficient FC, as shown in FIG. 4 (c), the frequency characteristic of the measured sound is substantially opposite to the frequency characteristic of FIG. 4 (a) (FIG. 4 (b)). As a result of being corrected by (see), it is close to the ideal pink noise. As described above, it can be seen that the sound field in the vehicle interior is corrected by using the sound field correction data obtained by executing the sound field correction data calculation process according to the present embodiment.

In this embodiment, since the installation position of each speaker SP is the sound receiving point of the test sound, a particularly high sound field correction effect (test sound is output from each speaker SP) in the vicinity of the installation position of each speaker SP in the vehicle interior. If this is the case, a sound having the frequency characteristics shown in FIG. 4C) can be obtained. Further, since each speaker SP is installed at the door portion near each seat, the sound field correction effect can be obtained also in each seat.

Further, in the present embodiment, as described above, the speakers SP _FR , SP _FL , SP _RR , and SP _RL are the door portion D _{FR on the driver's seat side, the door portion D FL} on the passenger seat side, and the right side of the rear seat, respectively. It is installed on the door D _{RR and the door D RL} on the left side of the rear seats. By using the counter electromotive force generated by each of the speaker SPs installed in this way, the sound field correction data in the area near each door (installation area of each speaker SP) is calculated independently. This makes it possible to appropriately correct the sound field in the installation area of each speaker. According to another viewpoint, each speaker SP is installed at each position on the front side, the rear side, the right side, and the left side in the vehicle A. By installing the speaker SPs at the front, rear, left, and right positions in the vehicle A in this way, the speaker SPs are located near the seats in the front side, the rear side, the right side, and the left side of the vehicle A. .. Therefore, a high sound field correction effect can be obtained in the vicinity of each seat. Further, by installing each speaker SP at each position in the front, rear, left and right in the vehicle A, the sound reproduced by the speaker SP can be heard from all directions to the user's ear regardless of which seat the user sits in the vehicle interior. It will arrive. Therefore, the user can perceive a spacious sound.

The above is the description of the exemplary embodiment of the present invention. The embodiments of the present invention are not limited to those described above, and various modifications can be made within the scope of the technical idea of the present invention. For example, the embodiment of the present application also includes the content obtained by appropriately combining examples and the like or obvious examples and the like as exemplified in the specification.

In the above embodiment, the test sound is output from the speaker SP at a predetermined cycle, and the frequency characteristics of the back electromotive force signal S'derived from the arrival wave generated in each period when the test sound is not output are averaged. , The calculation accuracy of the frequency characteristic of the counter electromotive force signal S'is improved. In another embodiment, the test sound is output from the speaker SP for a certain period of time (that is, is output only once), and the frequency characteristic of the countercurrent power signal S'after the output of the test sound is stopped is calculated (that is, that is). , The frequency characteristic of the countercurrent power signal S'may be calculated once). In this case, the load of calculating the frequency characteristics by the microcomputer 12 is suppressed.

The number and position of speaker SPs to be installed are not limited to those exemplified in the above embodiment. In another embodiment of the present invention, the speaker SP may be installed, for example, in the headrest of a seat. FIG. 5 schematically shows a vehicle in which a sound field correction system according to another embodiment of the present invention is installed.

As shown in FIG. 5, in another embodiment of the present invention, the speakers SP _FR , SP _FL , SP _RR , and SP _RL are the driver's seat headrest HR _FR , the passenger's seat headrest HR _FL , and the rear seat, respectively. It is installed in the right headrest HR _RR and the left headrest HR _{RL in the rear seats.} In this case, the sound receiving point (speaker SP installation position) is close to the ear of the user sitting in the seat. Therefore, a particularly high sound field correction effect (sound having the frequency characteristics shown in FIG. 4C when a test sound is output from each speaker SP) can be obtained in the vicinity of the user's ear.

Further, in the above embodiment, the sound field correction device 2 has a function of calculating the sound field correction data (in other words, the sound field correction data calculation device is built-in), but another embodiment. In the embodiment, the sound field correction data calculation device may be a device different from the sound field correction device 2 such as a notebook PC in which software for realizing the function is installed. In this case, another device is connected to each of the sound field correction device 2 and the speaker SP by wire or wirelessly. Another device calculates the filter coefficient FC based on the counter electromotive force signal S'from the arrival wave input from the speaker SP, and transmits it to the sound field correction device 2. The sound field correction device 2 corrects the sound field in the vehicle interior by performing equalizing using the filter coefficient FC received from another device.

As described above, the sound field correction data calculation device according to the embodiment of the present invention corrects the sound field generated by the sound output from the speaker by correcting the frequency characteristic of the sound output from the speaker. It is a device that calculates sound field correction data. It is an output unit that outputs a predetermined sound from the speaker, and when the speaker receives a reflected wave of the predetermined sound and a back-up force is generated in the speaker, the back-up occurs. The sound field correction data is calculated based on the detection unit that detects the signal generated by the power, the calculation unit that calculates the frequency characteristics of the detection signal detected by the detection unit, and the frequency characteristics of the detection signal calculated by the calculation unit. It has a calculation unit.

In the sound field correction data calculation device configured in this way, when a countercurrent force is generated in the speaker due to the speaker receiving a reflected wave of a predetermined sound, the signal generated by the generated countercurrent force is detected and detected. The sound field correction data is calculated using the signal. Therefore, when calculating the sound field correction data, it is not necessary to collect the sound output from the speaker by using an independent microphone as a device. That is, in the sound field correction data calculation device according to the embodiment of the present invention, by utilizing the above-mentioned counter electromotive force generated in the speaker, the sound can be collected without using an independent microphone as a device. It is possible to calculate the sound field correction data.

Further, in one embodiment of the present invention, the output unit may be configured to intermittently output a predetermined sound from the speaker. In this case, when the back electromotive force is generated by the speaker receiving the reflected wave of the predetermined sound during each period when the speaker does not output the predetermined sound, the detection unit outputs a signal generated by the generated back electromotive force. To detect. In addition, the calculation unit calculates the frequency characteristics of the detection signal of each period detected by the detection unit, and averages the frequency characteristics of the calculated detection signals of each period. Further, the calculation unit calculates the sound field correction data based on the frequency characteristics of the averaged detection signal.

In this way, by outputting a predetermined sound from the speaker for a certain period of time or intermittently, for example, a signal that is not affected by the back electromotive force generated by passing a signal of the predetermined sound through the speaker (that is, the speaker It is possible to detect a signal generated only by the counter electromotive force generated by receiving the reflected wave).

Further, in one embodiment of the present invention, the speaker is installed, for example, in the headrest of a seat in a vehicle. In this case, the sound field correction data is based on the signal generated by the countercurrent force generated by the reflected wave received by the speaker installed in the headrest (in other words, based on the sound heard at the position of the speaker installed in the headrest). Is calculated, for example, a high sound field correction effect can be obtained near the ear of the user sitting in the seat.

Further, the sound field correction data calculation device according to the embodiment of the present invention corrects the sound field generated by the sounds output from the plurality of speakers by correcting the frequency characteristics of the sounds output from the plurality of speakers. , A device that calculates sound field correction data, and receives an output unit that outputs a predetermined sound from a plurality of speakers, and each speaker receives a reflected wave of a predetermined sound output from at least each of the plurality of speakers. As a result, when a countercurrent force is generated in the speaker, a detection unit that detects the signal generated by the generated countercurrent force, a calculation unit that calculates the frequency characteristics of the detected signal for each speaker detected by the detection unit, and each speaker. It is provided with a calculation unit that calculates sound field correction data for each speaker based on the frequency characteristics of the detection signal calculated in 1.

In the sound field correction data calculation device configured in this way, when a countercurrent force is generated in each speaker due to each speaker receiving a reflected wave of a predetermined sound, a signal generated by the generated countercurrent force is detected. , The calculation of the sound field correction data using the detected signal is performed for each speaker. Therefore, when calculating the sound field correction data, it is not necessary to collect the sound output from each speaker by using an independent microphone as a device. That is, in the sound field correction data calculation device according to the embodiment of the present invention, by using the above-mentioned counter electromotive force generated in each speaker, it is not necessary to collect sound using an independent microphone as a device. , It is possible to calculate the sound field correction data for each speaker.

Further, the sound field correction system according to the embodiment of the present invention is installed in a vehicle, and has four or more speakers, an output unit that outputs a predetermined sound from the four or more speakers, and each speaker. When a countercurrent force is generated in a speaker by receiving a reflected wave of a predetermined sound output from at least four or more speakers, a detection unit that detects a signal generated by the generated countercurrent force and a detection unit A calculation unit that calculates the frequency characteristics of the detection signal for each speaker detected by the unit, a calculation unit that calculates sound field correction data for each speaker based on the frequency characteristics of the detection signal calculated for each speaker, and a calculation unit. The sound field generated by the sound output from four or more speakers by correcting the frequency characteristics of the sound output from each of the four or more speakers based on the sound field correction data of each speaker calculated by It is provided with a correction unit for correcting the above.

In the sound field correction system configured in this way, the sound field correction data in the installation area of each speaker is calculated independently by using the counter electromotive force generated by each of the four or more speakers. It is possible to appropriately correct the sound field in the installation area of each speaker.

Further, in the sound field correction system according to the embodiment of the present invention, at least one speaker is installed at each position of the front side, the rear side, the right side, and the left side in the vehicle, for example.

By installing the speakers at the front, rear, left, and right positions in this way, the speakers can be positioned near the seats in the front, rear, right, and left areas of the vehicle interior. Sound field correction based on the signal generated by the counter electromotive force generated by the reflected wave received by the speakers installed near each seat (in other words, based on the sound heard at the position of the speakers installed near each seat). Since the data is calculated, a high sound field correction effect can be obtained in the vicinity of the user sitting in each seat.

1 Sound field correction system 2 Sound field correction device 12 Microcomputer 14 DSP
16 Output circuit 18 Operation unit 20 Test signal generation circuit 22 _FR , 22 _FL , 22 _RR , 22 _RL Amplifier circuit 122 CPU
124 ROM
124A Frequency characteristic calculation program 124B Sound field correction data calculation program 126 RAM
128 Flash memory 142 Equalizer section SP _FR , SP _FL , SP _RR , SP _RL Speaker M Magnetic circuit C Voice coil V Cone type diaphragm

Claims (6)

In a sound field correction data calculation device that calculates sound field correction data, which corrects the sound field generated by the sound output from the speaker by correcting the frequency characteristics of the sound output from the speaker.
An output unit that outputs a predetermined sound from the speaker,
When a counter electromotive force is generated in the speaker due to the speaker receiving a reflected wave of the predetermined sound, a detection unit that detects a signal generated by the generated counter electromotive force, and a detection unit.
A calculation unit that calculates the frequency characteristics of the detection signal detected by the detection unit, and
A calculation unit that calculates the sound field correction data based on the frequency characteristics of the detection signal calculated by the calculation unit, and a calculation unit.
A storage unit that stores predetermined initial correction data in advance,
Equipped with a,
The output unit
The predetermined sound corrected by the initial correction data is output from the speaker.
Sound field correction data calculation device. The output unit
The predetermined sound is output from the speaker for a certain period of time.
The detection unit
When the counter electromotive force is generated by the speaker receiving the reflected wave of the predetermined sound after the output of the predetermined sound from the speaker is stopped, the signal generated by the generated counter electromotive force is detected.
The sound field correction data calculation device according to claim 1. The output unit
The predetermined sound is intermittently output from the speaker, and the sound is intermittently output.
The detection unit
When the counter electromotive force is generated by the speaker receiving the reflected wave of the predetermined sound during each period when the predetermined sound is not output from the speaker, the signal generated by the generated counter electromotive force is detected. ,
The calculation unit
The frequency characteristics of the detection signal for each period detected by the detection unit are calculated, and the frequency characteristics are calculated.
The calculated frequency characteristics of the detected signals for each period are averaged and calculated.
The calculation unit
The sound field correction data is calculated based on the frequency characteristics of the averaged detection signal.
The sound field correction data calculation device according to claim 1. Further provided with an amplification unit that amplifies the signal generated by the generated back electromotive force.
The detection unit
The signal amplified by the amplification unit is detected and
The calculation unit
The frequency characteristics of the detection signal detected by the detection unit are calculated, and the frequency characteristics are calculated.
The calculation unit
The sound field correction data is calculated based on the frequency characteristics of the detection signal calculated by the calculation unit and the frequency characteristics of the reference.
The sound field correction data calculation device according to any one of claims 1 to 3. The speaker is
Installed on the headrest of the seat in the vehicle,
The sound field correction data calculation device according to any one of claims 1 to 4. The sound field correction data calculation device according to any one of claims 1 to 5.
The sound field generated by the sound output from the speaker is corrected by correcting the frequency characteristics of the sound output from the speaker based on the sound field correction data calculated by the sound field correction data calculation device. Correction part and
To prepare
Sound field correction device.

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