WO2007116802A1

WO2007116802A1 - Output control device, output control method, output control program, and recording medium

Info

Publication number: WO2007116802A1
Application number: PCT/JP2007/056840
Authority: WO
Inventors: Yoji Fukumoto
Original assignee: Pioneer Corporation
Priority date: 2006-04-05
Filing date: 2007-03-29
Publication date: 2007-10-18

Abstract

An output control device (100) controls outputs of a plurality of speakers (120) which can output different frequency bands (hereinafter, referred to 'output frequency band'). A detection unit (101) detects an output frequency band of each of the speakers constituting the plurality of speakers (120). A filter (102) performs a filter process by a predetermined cut-off frequency on an audio signal outputted from each of the speakers (120). According to the output frequency band detected by the detection unit (101), a control unit (103) controls the cut-off frequency of the filter (102). A channel quantity information acquisition unit (104) acquires channel quantity information on the sound source of the audio signal. An installation position information acquisition unit (105) acquires installation position information on each of the speakers (120).

Description

Specification

Output control device, output control method, output control program, and recording medium

The present invention relates to an output control device, an output control method, an output control program, and a recording medium that control outputs of a plurality of speakers having different output frequency bands. However, the use of the present invention is not limited to the above-described output control device, output control method, output control program, and recording medium.

Background art

Conventionally, in an audio device that outputs sound such as music, the output frequency of a speaker is adjusted using a high-nos filter (HPF) or the like so as to maximize the performance of the speaker system. In such an audio apparatus, for example, a sine wave signal of 20 Hz to 20 OHz is sequentially output from an oscillator, and sound output from a speaker is collected by a microphone. The microphone computer detects the level of the signal output from the microphone and detects the playback limit frequency of the speaker. Then, the cutoff frequency of the high-pass filter in the DSP is set to the regeneration limit frequency of the spinning force (see, for example, Patent Document 1 below).

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2003-076374

Disclosure of the invention

Problems to be solved by the invention

[0004] However, according to the above-described conventional technology, there is a problem that the output frequency band of the bass output speaker cannot be taken into consideration. Many audio devices use a multi-speaker system in which a plurality of speakers having different output bands are combined, or a speaker system having a subwoofer dedicated to a heavy bass output. An example of such a speaker system is the need to adjust the output of a low-frequency speaker together with a mid-high range speaker.

[0005] Further, according to the above-described prior art, only the signal detection level near a predetermined frequency (specifically, 200 Hz) determines the output limit frequency, and uses the output limit frequency as a cut-off signal. For this reason, the signal detection level varies depending on the surrounding environment of the speaker. One possible problem is the possibility. Another problem is that the cut-off frequency cannot be determined in consideration of the overlap and gap of output frequency bands of each speaker and the characteristics of the content to be reproduced.

[0006] Further, according to the above-described prior art, a sine wave is used as a signal for analyzing the output frequency of the speaker. In a sine wave, the output sound of a certain frequency may resonate or be absorbed. For this reason, the problem of the force S when the analysis accuracy of the output frequency is reduced is an example.

Means for solving the problem

[0007] In order to solve the above-described problems and achieve the object, the output control device according to the invention of claim 1 includes a plurality of speaker powers having different output frequency bands (hereinafter referred to as "output frequency bands"). Output control device for controlling the output of each of the plurality of speakers, detecting means for detecting the output frequency band of each of the speakers, and a predetermined cut for each of the audio signals output by each of the speakers A filter that performs a filtering process using an off-frequency, and a control unit that controls the cut-off frequency of the filter based on an output frequency band detected by the detection unit.

[0008] The output control method according to the invention of claim 12 is an output control method for controlling outputs of a plurality of speakers having different output frequency bands (hereinafter referred to as "output frequency bands"). A detection step for detecting the output frequency band of each speaker constituting a plurality of speakers, and a predetermined cutoff frequency for the audio signal output by each speaker based on the output frequency band detected by the detection step And a filtering process step for performing the filtering process according to the above.

[0009] An output control program according to the invention of claim 13 causes a computer to execute the output control method according to claim 12.

[0010] Further, a recording medium according to the invention of claim 14 is readable by a computer having the output control program according to claim 13 recorded thereon.

Brief Description of Drawings

FIG. 1 is a block diagram showing a functional configuration of an output control device.

FIG. 2 is a flowchart showing a procedure of output control processing by the output control device. FIG. 3 is a block diagram showing a hardware configuration of the audio device.

FIG. 4 is an explanatory diagram showing an arrangement of speakers in a vehicle mounted on an audio device.

[FIG. 5] FIG. 5 is a flowchart showing an outline of speaker output frequency control processing by DSP.

[FIG. 6] FIG. 6 is a flowchart showing a procedure for an analysis process of an output possible frequency band in the loudspeaker for middle and high tone output.

[FIG. 7] FIG. 7 is an explanatory diagram for explaining the discrimination processing of the output possible frequency band of the mid-high sound output speaker.

[FIG. 8] FIG. 8 is a flowchart showing a procedure of analysis processing of a frequency band that can be output by a speaker for low-frequency output.

FIG. 9 is an explanatory diagram for explaining the order analysis processing.

FIG. 10 is an explanatory diagram for explaining the attenuation level changing process according to the order of the low-pass filter.

[FIG. 11] FIG. 11 is an explanatory diagram for explaining a process of changing the attenuation level according to the order of the low-pass filter.

FIG. 12 is a diagram schematically showing an example of output characteristics of a speaker installed in a vehicle.

FIG. 13 is a diagram schematically showing another example of output characteristics of a speaker installed in a vehicle.

FIG. 14 is a diagram schematically showing another example of output characteristics of a speaker installed in a vehicle.

FIG. 15 is a diagram schematically showing another example of output characteristics of a speaker installed in a vehicle.

Explanation of symbols

100 output controller

101 detector 102 Huinoleta

103 Control unit

104 Number of channels information acquisition unit

105 Installation position information acquisition unit

120a-120c speaker

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of an output control device, an output control method, an output control program, and a recording medium according to the present invention will be described in detail with reference to the accompanying drawings.

[0014] (Embodiment)

First, the functional configuration of the output control device 100 that is relevant to the embodiment will be described. FIG. 1 is a block diagram showing a functional configuration of the output control apparatus. The output control device 100 includes a detection unit 101, a filter 102, a control unit 103, a channel number information acquisition unit 104, and an installation position information acquisition unit 105. The output frequency band (hereinafter referred to as “output frequency band”) The output of a plurality of speakers 120 (120a to 120c) with different (b) is controlled.

[0015] The plurality of speakers 120 are, for example, a bass output speaker whose output frequency band is equal to or lower than the first frequency, and the output frequency band is equal to or higher than a second frequency different from the first frequency. It is configured to include at least one speaker for medium to high sound output. The plurality of speakers 120 may be installed inside the vehicle.

The detection unit 101 detects output frequency bands of the speakers (120a to 120c) constituting the plurality of speakers 120, respectively. For example, the detection unit 101 outputs a reference signal in a predetermined frequency band as well as the power of each speaker (120a to 120c), and collects the reference signal output from each speaker 120a to 120c force to detect the frequency band. To do. Here, the predetermined frequency band is, for example, a band of 20 Hz to 20000 Hz. Further, when the low-frequency output speaker has a built-in low-pass filter, the detection unit 101 detects a frequency band based on the order of the low-pass filter.

[0017] The filter 102 performs filter processing with a predetermined cutoff frequency on the audio signals output from the speakers 120a to 120c. The filter is composed of, for example, a low-pass filter and a high-pass filter. Note that the filter 102 The filtering process may be performed on audio signals output from all speakers 120, or may be performed on audio signals output from some speakers 120.

The control unit 103 controls the cutoff frequency of the filter 102 based on the output frequency band detected by the detection unit 101. The control unit 103 controls the cutoff frequency based on, for example, channel number information acquired by a channel number information acquisition unit 104 described later and an output frequency band.

[0019] Specifically, when the sound source of the audio signal is 2 channels, the control unit 103 determines the frequency of the audio signal output from the middle / high tone output speaker and the audio output from the bass output speaker. The cutoff frequency is controlled so that it does not overlap with the signal frequency. In addition, when the sound source of the audio signal is multi-channel, the control unit 103 determines between the frequency of the audio signal output from the middle / high tone output speaker and the frequency of the audio signal output from the bass output speaker. The cut-off frequency is controlled so that there are no gaps.

The control unit 103 controls the cutoff frequency based on installation position information and an output frequency band acquired by an installation position information acquisition unit 105 described later. Specifically, the control unit 103 outputs the sound from the medium / high sound output speaker when at least one medium / high sound output speaker and one low sound output speaker are located on the back side of the listener who listens to the audio signal. The cutoff frequency is controlled so that the frequency of the audio signal and the frequency of the audio signal output by the speaker output for bass output do not overlap.

[0021] The channel number information acquisition unit 104 acquires channel number information of the sound source of the audio signal. The number of sound source channels is, for example, 2 channels when a CD is a sound source, and multichannel when a DVD is a sound source.

[0022] Installation position information acquisition section 105 acquires installation position information of each speaker 120a-120c. The installation position information acquisition unit 105 acquires, for example, information on which of the front speakers, rear speakers, center speakers, and the like each of the speakers 120a to 120c corresponds to.

Next, output control processing by the output control apparatus 100 will be described. FIG. 2 is a flowchart showing a procedure of output control processing by the output control device. In the flowchart of FIG. 2, the output control device 100 first detects each speaker 120a by the detection unit 101. A reference signal is output from ~ 120c (step S201). The reference signal is output to the even IJ for each of the speaker forces 120a to 120c. Next, the detector picks up the reference signal output from each of the speakers 120a to 120c (step S202), and detects the output frequency band of each of the speakers 120a to 120c (step S203).

Subsequently, the channel number information acquisition unit 104 acquires information about the number of channels of the sound source of the audio signal (step S204). Further, the installation position information acquisition unit 105 acquires the installation position information of each of the speaker forces 120a to 120c (step S205). The control unit 103 controls the cutoff frequency of the filter 102 based on the output frequency band detected in step S203, the information about the number of channels of the sound source, and the installation position information of each of the force 120a to 120c (step S206). ).

[0025] Then, filter processing is performed on the audio signals output from the speakers 120a to 120c by the filter 102 (step S207), and the processing according to this flowchart ends.

[0026] In addition to controlling the cut-off frequency by the control unit 103, for example, a filter setting value for two channels (cut-off frequency) and a filter setting value for multi-channel (cut-off frequency) are set in advance. It may be created and the set value may be recorded in the output control device 100 or in an external recording device. In this case, the control unit 103 reads the filter setting value corresponding to the number of channels acquired by the channel number information acquisition unit 104 from the recording device. Then, the cutoff frequency of the filter 102 is controlled using the read filter setting value. In this case, the filter setting values for 2-channel and multi-channel to be recorded in the recording device may be set by the user.

[0027] As described above, according to the output control apparatus 100, the output of a plurality of speakers 120 having different output frequency bands is controlled by performing filter processing in accordance with each speaker 120. Thereby, an appropriate sound field can be obtained even in a place where a plurality of speakers 120 are mixed. In particular, even in a place where a low sound output speaker and a medium / high sound output speaker are mixed, it is possible to appropriately perform the filtering process in accordance with the characteristics of the respective speakers 120. In addition, bass sounds are more susceptible to interference with longer wavelengths than treble sounds. The sound will be easy to hear. In this manner, each speaker 120 can be controlled in consideration of the difference in sound properties depending on the frequency.

[0028] Further, according to the output control apparatus 100, the cutoff frequency of the filter processing is controlled based on the number of sound source channels of the audio signal. As a result, the sound signal can be output by utilizing the characteristics of each sound source, and the content recorded in the sound source can be used more effectively.

[0029] Further, according to the output control apparatus 100, the cutoff frequency of the filter processing is controlled based on the installation position of each speaker 120. As a result, it is possible to output an audio signal in consideration of the characteristics of how the sound is heard, particularly the characteristics related to the bass.

[0030] Further, according to the output control device 100, a reference signal of 20Hz to 20000Hz is output from each speaker 120, and an output frequency band is detected. As a result, it is possible to prevent the detection accuracy of the output frequency band from being lowered due to resonance or sound absorption of only a reference signal having a predetermined frequency. Further, according to the output control device 100, when a low-pass filter is incorporated in the low-frequency sound output force, the frequency band is detected based on the order of the low-pass filter. As a result, the detection accuracy of the output frequency band of the bass output speaker can be improved.

[0031] Furthermore, if the output control device 100 is used to control the speaker 120 installed inside the vehicle, the sound field inside the vehicle can be set appropriately. For example, it is possible to make the time spent in the vehicle more comfortable for the user, such as giving a sense of reality to the reproduction of content recorded in multi-channel.

Example

Next, an example of the output control device 100 that works according to the embodiment will be described. In the present embodiment, an example will be described in which the output control device 100, which is useful for the embodiment, is used for controlling the in-vehicle audio device 300.

[0033] (Hardware configuration of audio device 300)

First, the hardware configuration of the audio apparatus 300 will be described. FIG. 3 is a block diagram showing the hardware configuration of the audio device. Audio device 300 includes microcomputer 311, DSP (Digital Signal Processor) 312, DA converter 313, an electronic volume 314, an amplifier 315 (315a, 315b), a speaker 316, a microphone 317, an AD converter 318, and an audio source output unit 319.

The microcomputer 311 controls each component of the audio device 300. The DSP 312 generates an analysis signal used for analyzing the output frequency of the speaker 316. The DSP 312 performs frequency analysis of the output sound of the speaker 316 picked up by the microphone 317. Further, the DSP 312 constitutes a high pass filter (HPF) and a low pass filter (LPF), and adjusts the output sound of the speaker 316.

The DA converter 313 converts the digital signal input from the DSP 312 into an analog signal and outputs the analog signal to the electronic volume 314. The electronic volume 314 adjusts the analog signal input from the DSP 312 to a level corresponding to the control signal from the microcomputer 311 and outputs it to the amplifier 315a. The amplifier 315a amplifies the analog signal input from the electronic volume 314 and outputs it to the speaker 316.

The speaker 316 is installed in each part of the vehicle on which the audio device 300 is mounted. Here, the arrangement of speakers 316 in a vehicle on which audio device 300 is mounted will be described with reference to FIG. FIG. 4 is an explanatory diagram showing the arrangement of the speech force in the vehicle mounted on the audio device.

In FIG. 4, a vehicle 400 includes a center speaker CSp installed in front of the front seats 401a and 401b, a front spin force FSp installed in the left and right doors of the front seats 401a and 401b, and a rear seat 402. The rear speaker RSp installed at the left and right doors, the back center speaker BCSp provided at the rear of the rear seat 402, and the subwoofer SW provided at the left and right of the rear seat 402 are mounted!

[0038] The center speaker CSp, the front speaker FSp, the rear speaker RSp, and the knock center speaker force BCSp are each a speaker for outputting middle and high sounds. In addition, the subwoofer SW outputs a bass sound that cannot be output by a speaker for middle / high tone output. The audio signal output from each speaker 316 is filtered by the DSP 312. In addition, the arrangement of the speaker 316 is not limited to the above-mentioned form, and it is sufficient to provide at least one speaker for medium / high sound output and at least one subwoofer (SW) for low sound output! .

Returning to the explanation of FIG. 3, the microphone 317 is installed in each part of the vehicle, and each speaker 316 Therefore, the output sound is collected and converted into an analog signal. Then, the converted analog signal is output to the amplifier 315b. The amplifier 315b amplifies the analog signal input from the microphone 317 and outputs it to the AD converter 318. The AD converter 318 converts the analog signal input to the amplifier 315b into a digital signal and outputs it to the DSP 312. The digital signal output to the DSP 312 is used for the output frequency analysis of the speaker 316.

[0040] The audio source output unit 319 reproduces / receives an audio source such as a CD player, a DVD player, or an FMZAM tuner and outputs it as an audio source signal. In normal times, the audio source signal output from the audio source output unit 319 is output from the speaker 316 via the DSP 312 or the DA converter 313.

[0041] With the above configuration, the audio device 300 performs reproduction of music, reception of radio broadcasts, and the like. Here, a plurality of speakers 316 are installed inside the vehicle. Each speaker 316 has a different outputable frequency band, output characteristics, and the like. In addition, the frequency band and output characteristics that can be output vary depending on the installation position and the structure of the vehicle, even if the speakers have the same characteristics, such as sound absorption by the seat and reflection on the glass surface. Therefore, the audio device 300 performs an output frequency control process on each speaker 316 to adjust the sound field in the vehicle.

[0042] (Outline of output frequency control process)

Next, an outline of the output frequency control processing of the speaker 316 by the DSP 312 will be described. Fig. 5 is a flowchart showing an overview of the speaker output frequency control processing by the DSP. In the flowchart of FIG. 5, the DSP 312 first analyzes a frequency band (hereinafter referred to as an output possible frequency band) that can be output for a middle / high tone output speaker installed in the vehicle (step S501). The mid-high sound output speakers are, for example, the center speaker CSp, the front speaker FSp, the rear speaker RSp, and the back center speaker BCSp shown in FIG.

[0043] Further, the DSP 312 analyzes the frequency band that can be output for the low-frequency output speaker installed in the vehicle (step S502). The bass output speaker is, for example, the subwoofer SW shown in FIG. Note that either step S501 or step S502 may be performed first. Next, DSP 312 determines the cutoff frequency of the filter processing performed on the output signal of each speaker 316 based on the frequency band that can be output from each speaker 316 analyzed in steps S501 and S502 (step S503). ). Then, filter processing is performed on the audio signals respectively output from the middle / high tone output speaker and the low tone output speaker (step S504), and the processing according to this flowchart ends. Thereafter, an audio signal (sound) subjected to the filtering process is output from the speaker 316.

[0045] (Analysis processing of output possible frequency band in middle and high tone output speaker)

Next, details of processing in each step of the flowchart shown in FIG. 5 will be described. First, the analysis process (see step S501 in FIG. 5) of the frequency band that can be output by the loudspeaker for middle and high tone output will be described.

[0046] FIG. 6 is a flowchart showing the procedure of the analysis process of the output possible frequency band in the mid-high sound output speaker. In the flowchart of FIG. 6, the DSP 312 of the audio apparatus 300 first selects a medium / high tone output speaker for analyzing the frequency band that can be output from among a plurality of speakers 316 installed inside the vehicle (step S601).

[0047] Next, a measurement signal for frequency analysis is output from the loudspeaker for middle and high tone output selected in step S601 (step S602). The measurement signal for frequency analysis output at this time may be white noise, pink noise, time stretch pulse, impulse, etc. in addition to the sine wave. In particular, white noise, pink noise, time stretch pulses, and impulses contain components in all frequency bands, so the measurement time in the output frequency band can be shortened.

[0048] Subsequently, the measurement signal output from the mid-high sound output speaker is collected by the microphone 317 (step S603), and the output characteristics of the mid-high sound output speaker are analyzed (step S604). Then, based on the output characteristics analyzed in step S604, the output possible frequency band of the middle / high tone output speaker is determined (step S605).

[0049] Until all the mid-high sound output speakers are analyzed (step S606: No), the process returns to step S601, and the analysis of the output frequency band of each mid-high sound output speaker is continued. When the analysis of the output speaker is completed (step S606: Yes), the processing by this flow chart is terminated. In addition, all middle and high frequency output speakers installed in the vehicle For example, you may want to analyze only the mid-high sound output force specified by the user.

Here, the details of the discrimination process of the output possible frequency band in step S605 of FIG. 6 will be described with reference to FIG. FIG. 7 is an explanatory diagram for explaining the discrimination processing of the output possible frequency band of the middle / high tone output speaker. In Fig. 7, the horizontal axis represents the frequency of the measurement signal, the vertical axis represents the intensity of the measurement signal output from the speaker 316 (collected by the microphone 317), and the curve cl represents the output of the mid-high sound output speaker. Show properties.

[0051] The DSP 312 of the audio apparatus 300 first calculates an average value of the output intensity of the measurement signal in 20 Hz to 20000 Hz (20 kHz), that is, in the human audible band. At this time, the frequency band for calculating the average value is not limited to 20 Hz to 20 kHz. For example, a frequency band of 31.5 Hz to 16 kHz may be used. The average value of the output intensity can be calculated, for example, by dividing the frequency band by 1/3 octave, measuring the output level in the divided band, and calculating the average value. In Fig. 7, the intensity shown on the straight line (intensity al) is the average value of the output intensity at 20 Hz to 20 kHz.

Next, the DSP 312 detects a frequency (hereinafter referred to as “attenuation frequency”) at which the output intensity of the measurement signal attenuates by a certain level from the average value (intensity al) within a range of 200 Hz or less. Here, the reason why the attenuation frequency is detected even when the force is 200 Hz or less is that almost all mid-high sound output speakers can output in the frequency band of 200 Hz or more. In Fig. 7, the attenuation level is indicated by level dl and the attenuation frequency is indicated by pi.

[0053] Then, the frequency band from the attenuation frequency pi to the frequency one octave (loct) is determined as the output possible frequency band. In Fig. 7, the frequency one octave above the attenuation frequency pi is defined as the output limit frequency L1, and the band above the output limit frequency L1 is defined as the output possible frequency band of the mid-high tone output speaker. With the above procedure, the DSP 312 determines the output frequency band of each medium / high tone output speaker.

[0054] (Analysis processing of output possible frequency band in low-frequency output speaker)

Next, an analysis process (see step S502 in FIG. 5) of the output possible frequency band in the bass output speaker will be described. FIG. 8 is a flowchart showing the procedure of the analysis process of the output possible frequency band in the low-frequency output speaker. Figure 8 Flowchart In step S801, the DSP 312 of the audio apparatus 300 first selects a low-frequency output speaker that analyzes the output possible frequency band from among a plurality of speakers 316 installed in the vehicle.

Next, a measurement signal for frequency analysis is output from the bass output speaker selected in step S801 (step S802). The frequency analysis measurement signal output at this time may be white noise, pink noise, a time stretch pulse, an impulse, or the like in addition to a sine wave, as in the case of the mid-high sound output speaker.

[0056] Subsequently, the measurement signal output from the bass output speaker is collected by the microphone 317 (step S803), and the output characteristics of the bass output speaker are analyzed (step S804). Then, based on the output characteristics analyzed in step S804, the order of the low-pass filter V built in the low-frequency output speaker is analyzed (step S805).

[0057] Here, many low-frequency output speakers are integrated with an amplifier, a low-pass filter, and a speaker unit (such as a powered subwoofer). The order of the low-pass filter built into the low-frequency output speaker varies depending on the product.If the available frequency band is identified using the same method as the mid-high frequency output speaker shown in Figs. (Level dl in Fig. 7) is a fixed value, so the output possible frequency band is mistakenly determined.

[0058] For this reason, the DSP 312 analyzes the order of the low-pass filter before determining the output possible frequency band, and sets the attenuation level according to the order so that the accurate output possible frequency band can be determined. And

Note that the order defines the degree of output attenuation in the low-pass filter. For example, if the order of the low-pass filter is first order, it will attenuate by 6 decibels every octave higher. After that, as the order increases, the attenuation per octave increases by 6 decibels. For example, when the order is 3rd, it decreases by 18 decibels as the octave increases. Generally, the order of the low-pass filter incorporated in the powered subwoofer is 1st to 3rd.

[0060] The DSP 312 changes the attenuation level used to determine the frequency band that can be output according to the order of the low-pass filter analyzed in step S805 (step S806), The output possible frequency band of the bass output speaker is determined in the same procedure as that of the speaker (step S807).

[0061] Until all the bass output speakers are analyzed (step S808: No), the process returns to step S801, and the analysis of the output frequency band of each bass output speaker is continued, and all the bass output speakers are analyzed. When the outputable frequency band is analyzed (step S808: Yes), the processing according to this flowchart is terminated. As with mid-high sound output speakers, it is not necessary to analyze all low-frequency sound speakers mounted on the vehicle.For example, only the output frequency band of the low-frequency sound speakers specified by the user It is good to analyze.

Here, the details of the order analysis processing of the low-pass filter in step S805 of FIG. 8 will be described with reference to FIG. FIG. 9 is an explanatory diagram for explaining the order analysis processing. In FIG. 9, the horizontal axis represents the frequency of the measurement signal, the vertical axis represents the intensity of the measurement signal output from the bass output speaker, and the curve c2 represents the output characteristic of the bass output speaker.

[0063] The DSP 312 of the audio apparatus 300 first calculates the average value of the output intensity of the measurement signal in 20 Hz to 200 Hz. The procedure for calculating the average value is the same as that for a mid-high sound output speaker. However, the average value range is 20Hz to 200Hz because the frequency range that can be output for the mid-high sound output power is taken into account. by. In Fig. 9, the intensity shown on the straight line (intensity a2) is the average value of the output intensity from 20Hz to 200Hz.

[0064] Next, the DSP 312 detects an attenuation frequency at which the output intensity of the measurement signal is attenuated by a certain level from the average value (intensity a2) in a range of 200 Hz or more. In Fig. 9, the attenuation level is indicated by level d2, and the attenuation frequency is indicated by p2. Then, the change in the output intensity within one octave range is calculated around the attenuation frequency p2. That is, the slope of the section sO on the curve c2 indicated by the bold line in FIG. 9 is calculated. Then, the DSP 312 determines that the degree is higher as the slope of the section sO is larger and the degree is lower as the slope is higher, and varies the attenuation level.

Next, the attenuation level changing process according to the order of the low-pass filter in step S806 of FIG. 8 will be described with reference to FIGS. 10 and 11. FIG. FIG. 10 and FIG. 11 are explanatory diagrams for explaining the attenuation level changing process according to the order of the low-pass filter. [0066] In FIGS. 10 and 11, the horizontal axis represents the frequency of the measurement signal, the vertical axis represents the intensity of the measurement signal output from the bass output speaker, and the curves c3 and c4 represent the output characteristics of the bass output speaker. Show. The direction of the curve c3 shown in Fig. 10 Compared with the curve c4 shown in Fig. 11, the degree of attenuation in the high frequency band is large and the order is high. The intensities a3 and a4 are average values of the output intensities of the measurement signals in the respective bass output speakers.

[0067] The DSP 312 increases the attenuation level of the bass output speaker having a low-pass filter having a high order, and sets the attenuation level of the bass output speaker having a low-pass filter having a low order small. That is, as shown in FIG. 10, the attenuation level is increased as shown by level d3 for a low-frequency output speaker having a high-order low-pass filter. Also, as shown in FIG. 11, the attenuation level is reduced as shown by level d4 for a low-frequency output speaker having a low-pass filter with a low order.

[0068] Then, the output intensity of each bass output speaker, the strength a3, a4 force is the average value to determine the attenuation frequency p3, _P 4 to attenuated by attenuation level d3, d4. The frequencies one octave lower than the attenuation frequencies p3 and p4 are set as the output limit frequencies L3 and L4, and the bands below the output limit frequencies L3 and L4 are set as the output possible frequency ranges of the respective bass output speakers.

[0069] The output limit frequencies L3 and L4 are not limited to frequencies one octave lower than the attenuation frequencies p3 and p4. For example, the output limit frequencies L3 and L4 may be frequencies that attenuate by -10 dB from the average intensities a3 and a4. Through the above procedure, the DSP 312 determines the output possible frequency band of each middle / high tone output speaker.

[0070] (Cutoff frequency determination process)

Next, the cut-off frequency determination process (see step S503 in FIG. 5) will be described. As described above, the audio device 300 changes the filter processing setting (cut-off frequency) for each speaker 316 installed in the vehicle, and appropriately maintains the sound field of the vehicle.

Here, the audio device 300 takes into account the overlap and gap of the output possible frequency bands of the middle and high tone output speakers and the type of content to be reproduced, and the filter for each speaker 316. Determine processing settings. Conte to play Considering the type of input, for example, distinguishing 2ch sources such as CDs and multi-channel sources such as DVDs, and setting the optimal filtering settings for each source. The following describes how to determine the respective filter processing settings when the content to be played is a 2-channel source and when it is a multi-channel source.

[0072] It should be noted that, regardless of the type of content to be played back, the cut-off frequency of the high-pass filter of the medium / high tone output speaker is not set to be lower than the output possible band in principle. As a general rule, the cutoff frequency of the low-pass filter of the low-frequency output speaker shall not be set higher than the output possible band.

[0073] (When content to be played is 2ch source)

When the content to be played is a 2ch source, the same sound is output from the speakers 316 installed on the same left and right sides of each speaker 316 shown in FIG. For example, the same sound is output from the front speaker FSp on the front seat 401a side, the rear speaker force RSp installed on the right side of the rear seat 402, and the subwoofer SW installed on the right rear side of the rear seat 402. The subwoofer SW may output the left and right sound of the sound source in monaural.

[0074] Here, if the user's rear power low sound is viewed in the vehicle, the user feels uncomfortable. For this reason, bass output is performed by the front speaker FSp and the center speaker CSp that are positioned in front of the user as much as possible, and the subwoofer SW for bass output is used as an auxiliary.

FIG. 12 is a diagram schematically showing an example of output characteristics of a speaker installed in a vehicle. In Fig. 12, the horizontal axis indicates the frequency of the measurement signal, the vertical axis indicates the intensity of the measurement signal output from each speaker, and the line segments P (1) to P (3) indicate the output characteristic pattern (pattern) of the front speaker FSp. 1-3) are shown. Line SW indicates the output characteristics of the bass output speaker (subwoofer SW). In the line segments P (2), P (3), and SW, the points where the line segments are bent (points L (2), L (3), and L (SW)) indicate the output limit frequency of each speaker 316 Indicates.

[0076] Audio apparatus 300 first sets a power cutoff frequency for front speaker FSp and subwoofer SW, and then sets a cutoff frequency for rear speaker RSp. [0077] First, in the case of the front speaker FSp having the output characteristics of pattern 1 shown in the line segment P (l), the DSP 312 sets the cut-off frequency of the subwoofer SW to 80 Hz or lower. Here, the cut-off frequency is set to 80 Hz because it can be output by almost all low-frequency speakers in a frequency band of 80 Hz or less. The cut-off frequency may be 80Hz or less!

On the other hand, the DSP 312 does not set the cutoff frequency of the front speaker FSp. This is to fully utilize the bass output capability of the front speaker FSp. Also, since the front speaker FSp has sufficient bass output capability, it is possible not to output from the subwoofer SW.

[0079] In the case of the front speaker FSp having the output characteristics of the pattern 2 shown in the line segment P (2), the DS P312 sets the cutoff frequency of the subwoofer SW according to the output limit frequency of the front speaker FSp. The cutoff frequency of the front speaker FSp is set according to the output limit frequency of the front speaker FSp.

[0080] In the case of the front speaker FSp having the pattern 3 output characteristics shown in the line segment P (3), since there is no band that can be output mutually, the DSP 312 sets the cutoff frequency of the subwoofer SW to Set according to the output limit frequency. The cutoff frequency of the front speaker force FSp is set according to the output limit frequency of the front speaker FSp.

[0081] Subsequently, the DSP 312 sets the cutoff frequency of the rear speaker RSp. In general, a low-frequency output speaker (subwoofer SW) is often installed in the rear of the vehicle, such as a trunk, in the vehicle, so there is no interference with the sound output from the rear speaker RSp that is also installed in the rear of the vehicle. I will wake you up. To avoid this, the DSP 312 prevents the occurrence of interference by increasing the cutoff frequency of the rear speaker RSp when the output band of the rear speaker RSp and the output band of the subwoofer SW overlap.

[0082] If the output band of the rear speaker RSp and the output band of the subwoofer SW overlap, the DSP312 outputs the output limit frequency L (SW) of the subwoofer SW set according to the front speaker FSp (see Fig. 12). ) To set the cutoff frequency of the rear speaker RSp. Determine. In addition, since the audio device 300 that is effective in the present embodiment is provided in the vehicle, the force that requires such processing is required. In the case of an audio device installed in a home or the like, the bass output speaker is in front of the user. Since it is installed, this kind of processing does not have to be performed.

[0083] By determining the cut-off frequency as described above, it is possible to output the bass sound that cannot be output by the mid-high sound output speaker by using the low-frequency output speaker power while making the best use of the output of the mid-high sound output speaker. it can.

[0084] It should be noted that the filtering process for the bass output speaker in accordance with the output limit frequency L (SW) is, for example, the average output intensity of the bass output speaker and the average output intensity of the mid-high tone output speaker power. Is equal to 3 dB from the average output intensity of each speaker 316 at the point where the output characteristics of the low-frequency output speaker and the output characteristics of the mid-high output speaker intersect. There are methods such as deciding and filtering. As a result, overlapping portions of outputs from the respective speakers 316 complement each other, and output in all frequency bands can be performed without causing the user to feel uncomfortable. For convenience of explanation, in the following diagram, the output limit frequency of a predetermined speaker 316 and the cut-off frequency of another speaker 316 determined in accordance with this output limit frequency are shown as the same frequency.

[0085] (When the content to be played is a multi-channel source)

When the content to be played is a multi-channel source (for example, 5.1 channel source), different sounds are output from each speaker 316 shown in FIG. Even if there are multiple low-frequency output speakers, the output signal source is the same, but the output frequency depends on the cutoff frequency set for each low-frequency output speaker. Bands may be different.

[0086] When the source of the content to be played back is recorded in a multi-channel format such as Dolby (registered trademark) or dts (registered trademark), the low-frequency component that cannot be output by the speaker for medium-high sound output, that is, medium-high sound output The bass line segment below the cut-off frequency set for the loudspeaker is output from the bass output speaker by the bus management function.

[0087] For this reason, the low-frequency output speaker is set to at least a medium-high frequency output speaker. It is desirable to have an output band greater than or equal to the cutoff frequency. On the other hand, if the cutoff frequency of the low-frequency output force is set high, it will cause sound accumulation, so it should be set as low as possible. With this in mind, the cut-off frequency for each speaker 316 is determined.

[0088] First, when it is determined that the low / high sound can be sufficiently output by the medium / high sound output speaker, the cutoff frequency of the medium / high sound output speaker is not set. On the other hand, if it is determined that the bass sound cannot be output sufficiently with only the medium / high sound output force, the cut-off frequency is determined as follows.

FIG. 13 is a diagram schematically showing another example of the output characteristics of the speaker installed in the vehicle. In Fig. 13, the horizontal axis represents the frequency of the measurement signal, the vertical axis represents the intensity of the measurement signal output from each speaker, and the line segments SP1 to SP4 represent the speakers for middle and high tone output (left and right front speakers FSp and left and right rear speakers). RSp) shows the output characteristics, and line segment SW shows the output characteristics of the low-frequency sound output power (subwoofer SW).

[0090] In the line segments SP1 to SP4 and the line segment SW, points where the line segments are bent (points L (SP1) to L

(SP4), point L (SW)) indicates the output limit frequency of each speaker 316. That is, of the line segments SP1 to SP4 and the line segment SW, the partial force parallel to the horizontal axis indicates the output possible frequency band of each speaker 316.

In FIG. 13, there is a portion that overlaps the output possible frequency band of all the mid-high sound output speakers and the output possible frequency band of the bass output speaker. In such a case, the DSP 312 performs a filtering process using the output limit frequency as a cut-off frequency for the mid-high sound output speaker.

[0092] For the low-frequency sound output speaker, the output limit frequency is the highest among the medium-high sound output speakers, that is, the filter is matched to the output limit frequency of the speaker 316 having the lowest low-frequency output capability. Perform processing. In the example shown in the figure, the low-frequency loudspeaker is filtered according to L (SP4), which is the output limit frequency of the loudspeaker for medium and high-pitched sound, whose output characteristics are indicated by the line segment SP4.

[0093] As described above, in addition to the case where the output possible frequency band of all the middle and high sound output speakers and the output possible frequency band of the low sound output speaker overlap, some middle and high sound output speakers In some cases, the output frequency band of the low-frequency speaker and the output frequency band of the bass output speaker overlap. For example, the output band of the rear speaker RSp or knock center speaker BCSp and the output band of the low sound output speaker may overlap among the speakers for medium and high sound output.

[0094] Generally, in a vehicle, a low-frequency output speaker is often installed at the rear of the vehicle, such as a trunk, so that the sound output from the rear speaker RSp or the back center speaker BCSp, also installed at the rear of the vehicle. Cause interference. To avoid this, the DSP312 increases the cutoff frequency of the rear speaker RSp or back center speaker BCSp when the output band of the rear speaker RSp or back center speaker BCSp and the output band of the bass output speaker overlap. To prevent interference.

FIG. 14 is a diagram schematically showing another example of the output characteristics of the speaker installed in the vehicle. The meaning of each symbol is the same as in FIG. In Fig. 14, the output band of the rear speaker RSp and the back center speaker BCS p, whose output characteristics are indicated by line segments SP1 and SP2, respectively, and the output band of the bass output speaker overlap.

[0096] In such a case, the DSP 312 sets the cutoff frequency of the rear speaker RSp and the back center speaker BCSp in accordance with the output limit frequency L (SW) of the bass output speaker. In addition, since the audio device 300 which is effective in the present embodiment is provided in the vehicle, in the case of an audio device installed in a home or the like, the bass output speaker is located in front of the user. Since it is installed, it is not necessary to perform this process.

FIG. 15 is a diagram schematically showing another example of the output characteristics of the speaker installed in the vehicle. As shown in Fig. 15, if there is a speaker 316 that does not overlap with the output frequency band of the bass output speaker among the middle and high tone output speakers, the cut-off frequencies of the middle and high tone output speakers are respectively This is the output limit frequency of speaker 316. In this case, a band that cannot be partially output is generated.

[0098] Among the mid-high sound output speakers, the speaker 316 (SP4 in the example of Fig. 14) that does not overlap with the output frequency band of the low-frequency sound output speaker is not available for the center speaker CSp. It is also possible to output from the speaker FSp. [0099] In addition to determining the cutoff frequency by the DSP 312 as described above, the cutoff frequency may be set by the user. In this case, the DSP 312 displays the output characteristics of the speaker on, for example, a display screen provided in the audio device 300 main body, and allows the user to set the cutoff frequency.

[0100] Furthermore, for example, a filter setting value for two channels (cutoff frequency) and a filter setting value for multiple channels (cutoff frequency) are created in advance, and these setting values are stored in the audio device 300. Alternatively, it may be recorded in an external recording device. In this case, the DSP 312 identifies the number of channels of the sound source when reproducing the audio signal, and reads the filter setting value for the corresponding number of channels. Then, the filter processing is performed using the read filter setting value. At this time, the filter setting values for 2-channel and multi-channel recording to the recording device can be set by the user.

[0101] As described above, according to the audio apparatus 300, the outputs of the plurality of speakers 316 having different output frequency bands are controlled by the filter processing in accordance with the output characteristics of the respective speakers 316. As a result, an appropriate sound field can be obtained even in a place where a plurality of speakers 316 are mixed. In particular, even in a place where a low sound output speaker and a medium / high sound output speaker are mixed, it is possible to appropriately perform a filtering process in accordance with the characteristics of each speaker 316. In addition, bass sounds are more likely to be heard because they tend to interfere with sounds with longer wavelengths than treble sounds. In this manner, each speaker 316 can be controlled in consideration of the difference in sound properties depending on the frequency.

[0102] Also, according to the audio apparatus 300, the cutoff frequency of the filter processing is controlled based on the number of sound source channels of the audio signal. As a result, the sound signal can be output by utilizing the characteristics of each sound source, and the content recorded in the sound source can be used more effectively.

[0103] Also, according to the audio apparatus 300, the cutoff frequency of the filter processing is controlled based on the installation position of each speaker 316. As a result, it is possible to output an audio signal in consideration of the characteristics of how the sound is heard, particularly the characteristics related to bass.

[0104] Also, according to the audio apparatus 300, a reference signal of 20Hz to 20000Hz is applied to each speaker 3. Output from 16 and detect the output frequency band. As a result, it is possible to prevent the detection accuracy of the output frequency band from being lowered by resonating or absorbing only the reference signal having a predetermined frequency. Also, according to the audio apparatus 300, when a low-pass filter is built in the low-frequency sound output force, the frequency band is detected based on the order of the low-pass filter. As a result, the detection accuracy of the output frequency band of the bass output speaker can be improved.

[0105] Furthermore, since audio device 300 controls speaker 316 installed inside the vehicle, the sound field inside the vehicle can be set appropriately. For example, it is possible to make the user spend more comfortable in the vehicle, such as giving a sense of reality to the playback of content recorded in multi-channel.

It should be noted that the output control method described in the present embodiment can be realized by executing a prepared program on a computer such as a personal computer or a workstation. This program is recorded on a computer-readable recording medium such as a hard disk, a flexible disk, a CD-ROM, an MO, and a DVD, and is executed when the recording medium force is also read by the computer. The program may be a transmission medium that can be distributed through a network such as the Internet.

Claims

The scope of the claims

[1] An output control device that controls the output of a plurality of speakers having different output frequency bands (hereinafter referred to as “output frequency bands”).

Detection means for detecting an output frequency band of each speaker constituting the plurality of speakers;

A filter for performing a filtering process with a predetermined cutoff frequency on the audio signal output from each speaker;

Control means for controlling the cutoff frequency of the filter based on the output frequency band detected by the detection means;

An output control device comprising:

[2] The plurality of speakers are:

At least a low-frequency sound output speaker whose output frequency band is equal to or lower than a first frequency, and a medium-high sound sound output speaker whose output frequency band is equal to or higher than a second frequency different from the first frequency. Consists of one by one

The detection means includes

The output control device according to claim 1, wherein the output frequency bands of the low-frequency output speaker and the middle / high-frequency output speaker constituting the plurality of speakers are respectively detected.

[3] Channel number information acquisition means for acquiring channel number information of the sound source of the audio signal,

The control means includes

3. The output control apparatus according to claim 2, wherein the cut-off frequency is controlled based on the channel number information acquired by the channel number information acquisition unit and the output frequency band.

[4] The control means includes

When the sound source of the audio signal is 2 channels, the frequency of the audio signal output by the middle / high tone output speaker and the frequency of the audio signal output by the bass output speaker do not interfere with each other. Features controlling off frequency The output control device according to claim 3.

[5] The control means includes

When the sound source of the audio signal is multi-channel, there is no gap between the frequency of the audio signal output by the middle / high tone output speaker and the frequency of the audio signal output by the bass output speaker. The output control device according to claim 3, wherein the output frequency is controlled by a cutoff frequency.

[6] An installation position information acquisition unit that acquires installation position information of each speaker is provided, and the control unit includes:

The output control apparatus according to claim 1, wherein the cutoff frequency is controlled based on the installation position information acquired by the installation position information acquisition means and the output frequency band.

[7] The control means includes

When at least one of the medium and high sound output speakers and the low sound output speaker are positioned on the back side of the listener who listens to the sound signal, the frequency of the sound signal output from the medium and high sound output speaker; 7. The output control apparatus according to claim 6, wherein the cut-off frequency is controlled so as not to interfere with a frequency of the audio signal output from the bass output speaker.

[8] The detection means includes

The reference signal in a predetermined frequency band is output from each of the speakers, and the reference signal output from each of the force is collected to detect the output frequency band. The output control device according to 1.

[9] The detection means includes

9. The output control device according to claim 8, wherein a reference signal for outputting the predetermined frequency band from 20 Hz to 20000 Hz is output.

[10] The detection means includes

The output control device according to claim 2, wherein when the low-frequency sound output speaker includes a low-pass filter, the frequency band is detected based on the order of the low-pass filter.

[11] The plurality of speakers are installed in a vehicle.

The output control device according to any one of 10.

[12] An output control method for controlling the output of a plurality of speakers having different output frequency bands (hereinafter referred to as “output frequency bands”),

A detection step of detecting each output frequency band of each speaker constituting the plurality of speakers;

A filtering process step of performing a filtering process at a predetermined cutoff frequency on the audio signal output from each speaker based on the output frequency band detected by the detecting step;

The output control method characterized by including.

13. An output control program that causes a computer to execute the output control method according to claim 12.

[14] A computer-readable recording medium on which the output control program according to claim 13 is recorded.