WO2004077402A1 - ディップフィルタの周波数特性決定方法 - Google Patents
ディップフィルタの周波数特性決定方法 Download PDFInfo
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- WO2004077402A1 WO2004077402A1 PCT/JP2004/002141 JP2004002141W WO2004077402A1 WO 2004077402 A1 WO2004077402 A1 WO 2004077402A1 JP 2004002141 W JP2004002141 W JP 2004002141W WO 2004077402 A1 WO2004077402 A1 WO 2004077402A1
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- frequency
- amplitude
- frequency characteristic
- dip
- characteristic
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R29/00—Monitoring arrangements; Testing arrangements
- H04R29/007—Monitoring arrangements; Testing arrangements for public address systems
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H13/00—Measuring resonant frequency
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
- H04R3/04—Circuits for transducers, loudspeakers or microphones for correcting frequency response
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2227/00—Details of public address [PA] systems covered by H04R27/00 but not provided for in any of its subgroups
- H04R2227/007—Electronic adaptation of audio signals to reverberation of the listening space for PA
Definitions
- the invention according to the present application relates to a method for determining a frequency characteristic of a dip filter used for preventing resonance in a space where acoustic equipment is arranged.
- the sound and loudspeakers from the loudspeakers are used due to the resonance frequency of this space (the loudspeaker space where the sound equipment is arranged).
- Voice is difficult to hear; That is, if a loud sound from a speaker contains many components of the resonance frequency, resonance occurs at the frequency of this component in the loud sound space.
- the resonance sounds like "Wong Won ⁇ ⁇ ⁇ " or "Fan fan ⁇ ⁇ ⁇ ". This resonance sound is not a sound that is supposed to radiate from speed, but makes it difficult to hear music and speech from speed.
- a dip filter that detects the resonance frequency in the loudspeaker space and removes the component of the resonance frequency in the sound equipment before the speaker may be provided. Then, resonance is less likely to occur in this loudspeaker space, so that music and speech from speakers can be easily heard.
- the frequency characteristics of the dip filter must be determined so that the resonance frequency of the loudspeaker space is used as the removal frequency.
- an operator of an acoustic facility or a measurer relies on his or her own hearing to distinguish the loudspeaker sound and resonance sound of a speaker to determine the resonance frequency, and sets this resonance frequency as a removal frequency in the dip fill.
- the attenuation level (depth) of the dip and its sharpness (Q) were set so that resonance did not occur. Even if the resonance frequency can be known by such discrimination, it is not easy to set the frequency characteristics of the dip-fill. In particular, it is not easy to properly set the dip attenuation level (depth) and sharpness (Q).
- an object of the present invention is to provide a method for determining a frequency characteristic of a dip filter, which can appropriately determine the characteristics of a dip filter without requiring experience or skill. .
- a method for determining a frequency characteristic of a dip filter determines a resonance frequency detected in a resonance space as a center frequency of the dip, and determines a predetermined frequency from a speaker arranged in the resonance space. Is loudspeaked, and a fundamental amplitude-frequency characteristic is obtained based on a measurement value obtained by receiving a sound by a microphone arranged in the resonance space. Based on the measurement value, a frequency axis is calculated based on the fundamental amplitude-frequency characteristic.
- a target amplitude frequency characteristic having a large smoothness is obtained above, and based on a difference between the basic amplitude frequency characteristic and the target amplitude frequency characteristic at the center frequency and frequencies near the center frequency, the attenuation level of the dip and Z Or determine the sharpness.
- the target amplitude frequency characteristic having a greater degree of smoothness on the frequency axis than the basic amplitude frequency characteristic is set as the target amplitude frequency characteristic. Therefore, the target amplitude frequency characteristic is objectively obtained, and based on this, the dip attenuation level and the sharpness can be objectively determined.
- the target amplitude frequency characteristic may be smoothed by any method, but may be smoothed by moving-averaging the measured amplitude frequency characteristic on the frequency axis. .
- the attenuation level and / or the sharpness of the dip is determined so that the second area substantially matches the first area.
- the first area has a logarithmic axis representing an amplitude level as a vertical axis, and a frequency as a frequency.
- the curve of the basic amplitude frequency characteristic and the curve of the target amplitude frequency characteristic are represented on an amplitude frequency characteristic diagram with the axis representing the horizontal axis, An area surrounded by the curve of the amplitude frequency characteristic and the curve of the target amplitude frequency characteristic, wherein the first frequency is such that the curve of the basic amplitude frequency characteristic intersects with the curve of the target amplitude frequency characteristic; And a frequency closest to the center frequency of the dip among frequencies lower than the center frequency of the dip, and the second frequency is a curve of the basic amplitude frequency characteristic and the target amplitude frequency characteristic.
- the curve intersects and is the frequency closest to the center frequency of the dip among the frequencies higher than the center frequency of the dip.
- the second area has a logarithmic axis representing the amplitude level as a vertical axis.
- the amplitude frequency characteristic with the axis representing frequency as the horizontal axis may be the area of the dip when the characteristic of the dip is represented on the diagram.
- the dip characteristic is applied to the basic amplitude frequency characteristic.
- the characteristics are close to the target amplitude frequency characteristics.
- the attenuation level of the dip is determined so as to substantially match the amplitude level difference between the basic amplitude frequency characteristic and the target amplitude frequency characteristic at the center frequency of the dip, and the sharpness of the dip is determined as The determination may be made such that the second area substantially matches the first area.
- the dip characteristic determined by such a method When the dip characteristic determined by such a method is applied to the basic amplitude frequency characteristic, the characteristic becomes very close to the target amplitude frequency characteristic.
- the resonance frequency having the largest amplitude level of the second amplitude frequency characteristic is determined as the center frequency of the dip, and the other resonance frequencies are determined not to be the center frequency of the dip.
- the second amplitude frequency characteristic may be an amplitude frequency characteristic obtained by loudspeaking a composite signal of the measurement signal and the output signal of the microphone from the speaker and receiving the sound by the microphone. Good.
- the resonance frequency of the resonance space is detected based on a comparison between the first amplitude frequency characteristic and the second amplitude frequency characteristic, and the first amplitude frequency characteristic is determined based on the measured value.
- the second amplitude frequency characteristic is obtained by loudspeaking a composite signal of the measurement signal and the output signal of the microphone from the speaker and receiving the sound by the microphone.
- the amplitude frequency characteristic may be used.
- the second amplitude frequency characteristic in this method is an amplitude frequency characteristic of a system including a feedback loop in which the output signal of the microphone is input to the speaker. Due to this feedback loop, the resonance characteristics of the resonance space appear more emphasized in the second amplitude frequency characteristic than in the first amplitude frequency characteristic. Therefore, by comparing the first amplitude frequency characteristic and the second amplitude frequency characteristic, the resonance frequency of the resonance space can be accurately detected.
- a peak having a larger amplitude in the second amplitude frequency characteristic than in the first amplitude frequency characteristic is obtained from a difference between the first amplitude frequency characteristic and the second amplitude frequency characteristic.
- the frequency of the point may be detected as the resonance frequency of the resonance space.
- a sine wave sweep signal is particularly effective as the measurement signal.
- FIG. 1 is a schematic configuration diagram of an acoustic system installed in a loudspeaker space.
- FIG. 2 is a schematic block diagram of a system for measuring amplitude frequency characteristics in a loudspeaker space.
- FIG. 3 is a schematic block diagram of a system for measuring amplitude frequency characteristics in a loudspeaker space.
- FIG. 4 schematically shows a first amplitude frequency characteristic of the loudspeaker space measured by the system of FIG. 2 and a second amplitude frequency characteristic of the loudspeaker space measured by the system of FIG. FIG.
- FIG. 5 is a frequency characteristic diagram showing an amplitude level difference between a first amplitude frequency characteristic of a curve C a in FIG. 4 and a second amplitude frequency characteristic of a curve C b.
- FIG. 6 is a frequency characteristic diagram obtained by extracting only the curve Cb from the frequency characteristic diagram of FIG.
- FIG. 7 is a frequency characteristic diagram showing a curve C a of the basic amplitude frequency characteristic and a curve C d of the target amplitude frequency characteristic.
- FIG. 8 is a frequency characteristic diagram showing a case where three candidate frequencies exist in a frequency range from a frequency f61 to a frequency f62.
- FIG. 9 is an amplitude frequency characteristic diagram of a dip whose center frequency is frequency f2.
- FIG. 1 is a schematic configuration diagram of a sound system installed in a public space (for example, a concert hall or a gymnasium) 40.
- This acoustic system includes a sound source device 2, a dip filter 4, an amplifier 12, and a speaker 13.
- the sound source device 2 may be, for example, a performance device such as a CD player for reproducing a music CD, or a microphone and a microphone.
- the sound source device 2 is shown outside the sound space 40 in FIG. 1, the sound source device 2 may be installed in the sound space 40.
- the sound source device 2 may be a microphone installed in the loudspeaker space 40.
- the dip filter 4 removes a signal component of a specific frequency from the signal from the sound source device 2 and sends it to the amplifier 12. ,
- the signal from the dip filter 4 is amplified by the amplifier 12 and transmitted to the speaker 13, and is amplified from the speaker 13 in the sound space 40.
- the loudspeaker space 40 has a resonance frequency
- the loudspeaker sound from the speaker 13 contains many components of the resonance frequency
- resonance occurs in the loudspeaker space 40, making it difficult to hear music and speech from the loudspeaker 13.
- an appropriate frequency characteristic is set to the dip filter 4
- resonance in the loudspeaker space 40 can be prevented without deteriorating the sound quality of the loudspeaker sound from the speaker 13.
- the frequency characteristic to be set in the dip filter 4 is determined.
- a method and apparatus for detecting a resonance frequency in the resonance space 40 will be described with reference to FIGS. 2 to 5. I do.
- FIG. 2 is a schematic block diagram of a system ⁇ ⁇ for measuring amplitude frequency characteristics in a loudspeaker space (for example, a concert hall or a gymnasium) 40.
- the system A includes a transmitter 11 serving as a sound source for generating a signal for measurement, an amplifier 12 for inputting a signal generated by the transmitter 11 and amplifying power, and a speaker 13 for inputting an output signal of the amplifier 12 and loudspeaking. And a microphone 14 for receiving a loud sound radiated by the speaker 13 and a measuring device 15 for inputting a sound reception signal of the microphone 14.
- the microphone 14 may be a sound level meter.
- the speaker 13 and the microphone 14 are arranged in a sound space 40.
- the microphone 14 is sufficiently far from the speaker 13 in the sound space 40.
- the microphone 14 is arranged at a position where the reflected sound in the loudspeaker space 40 can be received at a sufficiently large level with respect to the direct sound from the speaker 13.
- the transmitter 11 emits a sine wave signal whose frequency changes with time as a measurement signal. That is, the transmitter 11 transmits a sine wave sweep signal. In the sine wave sweep signal, the level of the sine wave is constant at each point in the frequency sweep.
- the measuring device 15 has a band pass filter whose center frequency changes with time. This bandpass filter changes the center frequency over time in response to the time change of the frequency of the sine wave sweep signal transmitted by the transmitter 11. Therefore, the measuring device 15 measures the amplitude characteristic of the frequency at that time by detecting the level of the sound receiving signal input from the microphone 14 through this bandpass filter. be able to.
- FIG. 3 is a schematic block diagram of a system B for measuring the amplitude frequency characteristic in the loudspeaker space 40.
- This system B is obtained by adding a path for synthesizing a certain signal to the system A shown in FIG.
- the system B in FIG. 3 includes a transmitter 11 serving as a sound source for emitting a signal for measurement, a mixing device 16, an amplifier 12 which receives an output signal of the mixing device 16 and amplifies the signal, and an amplifier 12
- the loudspeaker 13 includes a speaker 13 that receives the output signal of the speaker 12 and loudspeaks, a microphone 14 that receives the loudspeaker radiated by the speaker 13, and a measuring device 15 that receives a signal received by the microphone 14.
- the speaker 13 and the microphone 14 are arranged at the same position in the loudspeaker space 40 as in the system A in FIG.
- the transmitter 11, the amplifier 12, the speaker 13, the microphone 14, and the measuring device 15 in the system B in FIG. 3 are the same as those in the system A in FIG.
- the difference between the system B shown in FIG. 3 and the system A shown in FIG. 2 is that, in the system A shown in FIG. 2, the amplifier 12 receives a signal from the transmitter 11 and the system shown in FIG. In the case B, the amplifier 12 receives a signal from the mixing device 16.
- the mixing device 16 shown in FIG. 3 inputs the measurement signal (sine-wave sweep signal) from the transmitter 11 and the sound reception signal from the microphone 14, and synthesizes (mixes) these input signals. Output the composite signal (mixing signal).
- the method of measuring the amplitude frequency characteristics of the loudspeaker space 40 by the system A in FIG. 2 and the method of measuring the amplitude frequency characteristics of the loudspeaker space 40 by the system B in FIG. 3 have been described above.
- the amplitude frequency characteristic of the loudspeaker space 40 measured by the system A in FIG. 2 is called a first amplitude frequency characteristic
- the amplitude frequency characteristic of the loudspeaker space 40 measured by the system B in FIG. It is called the amplitude frequency characteristic of 2.
- FIG. 4 shows the first amplitude frequency characteristics of the loudspeaker space 40 measured by the system A in FIG. 2
- FIG. 3 is a characteristic diagram schematically showing In FIG.
- both the vertical and horizontal axes are logarithmic axes, the vertical axis represents the amplitude level, and the horizontal axis represents the frequency.
- the “amplitude level” is the logarithm of the ratio of a certain amplitude value (amplitude magnitude) to a reference value (reference magnitude). Usually, the unit is expressed in "dB".
- the curve C a shown by a solid line in FIG. 4 is the first amplitude frequency characteristic by the system A in FIG. 2, and the curve C b shown by a broken line is the second amplitude frequency characteristic by the system B in FIG. is there.
- Both system A in Fig. 2 and system B in Fig. 3 measure amplitude values at a number of frequency points.
- the amplitude value is measured at intervals of 1Z192 octaves.
- the measured values at these multiple points may be represented on the curves C a and C b as the first and second amplitude frequency characteristics of the loudspeaker space 40 without being smoothed on the frequency axis.
- it may be smoothed on the frequency axis by some method, and represented by curves C a and C b.
- smoothing may be performed by a moving average.
- a moving average of 9 points on the frequency axis may be applied to the measured values of many frequency points.
- a smoothed curve C a it is preferable to use a smoothed curve C b as well.
- the curve C a is obtained by a moving average of 9 points on the frequency axis
- the curve C b is also obtained by a moving average of 9 points on the frequency axis.
- the first amplitude frequency characteristic of the curve C a in FIG. 4 includes not only the characteristic of the acoustic system by the amplifier 12, the speaker 13, and the microphone 14 but also the characteristic of the resonance of the loudspeaker space 40. is there.
- the second amplitude frequency characteristic of the curve Cb in FIG. 4 also includes not only the characteristic of the acoustic system by the amplifier 12, the speaker 13, and the microphone 14, but also the characteristic of the resonance of the loudspeaker space 40. Due to the feedback loop in which the output signal of the microphone 14 is input to the amplifier 12 and output from the speed 13, the resonance characteristic of the loudspeaker space 40 is larger than the first amplitude frequency characteristic of the curve C a. It is emphasized. Therefore, the resonance characteristics of the loudspeaker space 40 can be known from the difference between the two curves (the curves C a and C b).
- the frequency characteristic curve C c shown in FIG. 5 is a characteristic obtained by subtracting the characteristic of the curve C a from the characteristic of the curve C b of FIG. 4, that is, the first amplitude frequency characteristic of the curve C a and the characteristic of the curve C b It shows an amplitude level difference from the second amplitude frequency characteristic.
- the frequencies that show a positive peak in the curve Cc in FIG. 5 are the frequencies f1, f2 and f2. 2004/002141
- the frequency f 3 having the highest peak value is most likely to be the resonance frequency of the loudspeaker space 40.
- the frequency f 2 has the second largest peak value, the frequency: f 2 is likely to be the resonance frequency of the loudspeaker space 40, which is the second highest.
- the number of resonance frequencies in the loudspeaker space 40 is not limited to one, but may be more than one. Therefore, only one of the frequencies ⁇ 1, f2, and f3 may be the resonance frequency, and some of them may be the resonance frequencies, but the resonance frequency is determined from the characteristics in FIG. A possible frequency can be objectively selected. The method and apparatus for detecting the resonance frequency in the resonance space 40 have been described above with reference to FIGS.
- the curve Ca in FIG. 4 is a first amplitude frequency characteristic curve of the loudspeaker space 40 obtained by the system A in FIG. 2, and the resonance frequency is detected using the curve Ca as described above.
- the characteristic of the curve Ca is also used for determining the frequency characteristic of the dip fill 4 of the acoustic system of FIG. 1 described below.
- the characteristic of the curve C a is referred to as “basic amplitude frequency characteristic”. Note that this “basic amplitude frequency characteristic” may be a value obtained by smoothing the measured values at a number of frequency points by the system A in FIG. 2 on the frequency axis or not. There may be.
- the frequency f1, the frequency f2, and the frequency f3 were obtained from the frequency characteristic curve C shown in FIG. 5 as frequencies showing peaks in the positive direction. It is highly possible that these frequencies are the resonance frequencies of the loudspeaker space 40. From this, a predetermined number of frequencies are selected as candidates for the center frequency of the dip to be set as the removal frequency in the dip filter 4.
- candidate frequencies are selected in order from the one with the largest amplitude level of the curve Cb in FIG.
- FIG. 6 is a characteristic diagram obtained by extracting only the curve Cb from FIG.
- both the vertical and horizontal axes are logarithmic axes, with the vertical axis representing amplitude level and the horizontal axis representing frequency.
- the amplitude level at the frequency: f2 is the largest
- the amplitude level at f3 is the next largest
- the amplitude level at f1 is the next largest.
- the number of frequencies to be selected as candidates is “3”
- all of the frequencies f 1, f 2 and f 3 are candidate frequencies.
- the candidate frequencies (frequency ⁇ 1, ⁇ 2, f 3) are ranked.
- the order of the frequency characteristic curve Cc in FIG. Among the frequencies f 1, f 2 and f 3, the frequency f 3 has the largest amplitude level in the curve C c in FIG. 5, and the frequency level f 2 has the second largest amplitude level.
- the next largest amplitude level is frequency ⁇ ⁇ 1. Therefore, at this point, the frequency f3 is the frequency of the first candidate, the frequency f2 is the frequency of the second candidate, and the frequency f1 is the frequency of the third candidate.
- the target amplitude frequency characteristic is obtained from the measured values measured at a number of frequency points by the system A in FIG.
- the target amplitude frequency characteristic is obtained by smoothing the measured values measured by the system A in FIG. 2 at a number of frequency points on the frequency axis.
- the smoothing method for example, a moving average on the frequency axis can be adopted.
- the curve C a (basic amplitude frequency characteristic) in FIG. 4 may be obtained by smoothing the measured values measured by the system A in FIG. 2 at a number of frequency points on the frequency axis, He stated that it may be unsmoothed.
- the basic amplitude frequency characteristic may or may not be smoothed, but the target amplitude frequency characteristic is obtained by smoothing.
- the target amplitude frequency characteristic is obtained by smoothing such that the smoothness on the frequency axis is larger than the basic amplitude frequency characteristic. If the fundamental amplitude frequency characteristic is obtained by a moving average of, for example, 9 points on the frequency axis,
- the target amplitude frequency characteristic may be obtained by a moving average of a window width exceeding 9 points (for example, 65 points). In this way, the target amplitude frequency characteristics can be obtained objectively without relying on experience.
- the curve Ca is extracted from FIG. 4 and described.
- both the vertical and horizontal axes are logarithmic axes, with the vertical axis representing amplitude level and the horizontal axis representing frequency.
- the curve C a in FIG. 7 is the same as the curve C a in FIG.
- the characteristic diagram in Fig. 7 shows a dashed curve C d (curve C d), which represents the amplitude values at a number of frequency points measured by system A in Fig. 2, It is a curve obtained by moving average on the axis. Since the window width for the moving average at this time is relatively large, the smoothness of the curve C d (target amplitude frequency characteristic) is considerably larger than that of the curve C a (basic amplitude frequency characteristic).
- frequency f3 was selected as the first candidate frequency
- frequency f2 was selected as the second candidate frequency
- frequency f1 was selected as the third candidate frequency.
- the target amplitude was selected.
- Frequencies in which the amplitude level of the fundamental amplitude frequency characteristic (curve C a) is smaller than the amplitude level of the frequency characteristic (curve C d) are excluded from candidates.
- the amplitude level of the basic amplitude frequency characteristic (curve C a) is smaller than the amplitude level of the target amplitude frequency characteristic (curve C d). Therefore, the frequency f1 is excluded from the candidate frequencies.
- the candidate frequencies are only the frequency f2 and the frequency f3.
- the frequency f3 remains as the first candidate frequency
- the frequency f2 remains as the second candidate frequency.
- the curve C a of the basic amplitude frequency characteristic from the curve C d of the target amplitude frequency characteristic is continuously positive on the frequency axis.
- the frequency range protruding in the direction is detected.
- the frequency of the first candidate is frequency f3, in FIG. 7, at frequency f3, the amplitude level of the basic amplitude frequency characteristic is higher than the target amplitude frequency characteristic.
- the curve C a of the fundamental amplitude frequency characteristic intersects with the curve C d of the target amplitude frequency characteristic.
- Frequency f 31 is better than frequency ⁇ '3 Among the intersections between the curve C a of the fundamental amplitude frequency characteristic and the curve C d of the target amplitude frequency characteristic in the lower frequency region, the frequency closest to the frequency ⁇ 3.
- the frequency f32 is a frequency closest to the frequency f3 among intersections of the curve Ca of the fundamental amplitude frequency characteristic and the curve Cd of the target amplitude frequency characteristic in a frequency region higher than the frequency f3. .
- the candidate frequency f 3 is included, and the curve C a of the fundamental amplitude frequency characteristic is continuously shifted from the curve C d of the target amplitude frequency characteristic in the positive direction (upward) on the frequency axis.
- the protruding frequency range the range from frequency f31 to frequency 32
- the candidate frequency includes only the frequency 3, so that no frequency is excluded from the candidate.
- the candidate frequency f2 the frequency range in which the frequency f2 is included, the frequency where the fundamental amplitude frequency characteristic (curve C a) from the target amplitude frequency characteristic (curve C d) continuously protrudes in the positive direction on the frequency axis.
- a number range is first detected. As shown in Fig. 7, in the frequency range from frequency f21 to frequency ⁇ 22, the fundamental amplitude frequency characteristic (curve C a) from the target amplitude frequency characteristic (curve C d) continuously appears on the frequency axis. It protrudes in the positive direction.
- the frequency range includes the frequency f2. Next, looking at whether this frequency range includes two or more candidate frequencies, there is no candidate frequency other than frequency f2 in this frequency range. Therefore, no frequencies are excluded from the candidate in this frequency range.
- the curve Ce in the characteristic diagram of FIG. 8 is a curve indicating the basic amplitude frequency characteristic
- the curve Cf is a curve indicating the target amplitude frequency characteristic. Both The curve intersects at frequency: f61 and frequency f62, and three frequencies (frequency f51, frequency f52) that are candidates for this frequency range (frequency range from frequency f61 to frequency: f62) And the frequency f53) exists.
- a curve Cn represents a second amplitude-frequency characteristic, that is, a signal obtained by amplifying a composite signal of the measurement signal (sine-wave sweep signal) from the speaker 13 and the output signal of the microphone 14 in the resonance space 40.
- 4 shows amplitude frequency characteristics obtained by receiving sound with the microphone 14.
- the amplitude level of the second amplitude frequency characteristic (curve Cn) is the largest at the frequency f51. Therefore, only the frequency ⁇ 51 is left as a candidate frequency, and the other frequencies (frequency f52 and frequency f53) are excluded from the candidate. This prevents more than necessary frequencies from remaining as candidate frequencies. As a result, more dips than necessary are prevented from being set in the dip filter 4.
- the candidate frequencies (frequency ⁇ , frequency f2, frequency f3) have a difference in amplitude level between the fundamental amplitude frequency characteristic (curve Ce) and the second amplitude frequency characteristic (curve Cn) below a predetermined level (for example, l If the frequency is less than (dB), the frequency should not be set as the center frequency of the dip in dip filter 4.
- the fundamental amplitude frequency characteristic at the frequency f51 (curve Ce) If the amplitude level difference between the second amplitude frequency characteristic (curve Cn) and the second amplitude frequency characteristic (curve Cn) is equal to or less than a predetermined level (for example, ldB or less), the frequency f51 is excluded from the candidate frequencies, and the second amplitude frequency characteristic (curve Cn) The frequency f52 having the next largest amplitude level is left as a candidate frequency. Of course, the frequency f53 is excluded from the candidate frequencies.
- a predetermined level for example, ldB or less
- Fig. 7 it is the frequency range that includes the candidate frequency, and the target amplitude frequency characteristic (curve Cd) to the basic amplitude frequency characteristic (curve Ca) continue in the positive direction on the frequency axis.
- the protruding frequency range was first detected. Then, each detected frequency range does not include more than one candidate frequency, and It was explained that the complementary frequencies f2 and f3 remain as candidates without being excluded.
- the remaining frequency candidates are rearranged in the candidate order.
- the replacement is performed as follows. In other words, the order is changed so that the higher the amplitude level difference between the basic amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) at the candidate frequency, the higher the rank.
- the amplitude level difference between the fundamental amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) at frequency: f2 is 2.5 dB, and at frequency f3.
- the amplitude level difference between the fundamental amplitude frequency characteristic (curve Ca) and the target amplitude frequency characteristic (curve Cd) is 1.8 dB. Therefore, the order of the candidates is changed, and the frequency f2 becomes the first candidate, and the frequency: f3 becomes the second candidate.
- the first candidate, frequency ⁇ 2 was determined to be set as the center frequency (removal frequency) of the dip in dipfill 4.
- the procedure for determining the dip attenuation level (depth) and the sharpness (Q) at the removal frequency (frequency f 2) will be described.
- the magnitude of the amplitude level difference between the target amplitude frequency characteristic (curve Cd) and the fundamental amplitude frequency characteristic (curve Ca) at frequency ⁇ 2 is detected, and this magnitude (the magnitude of the difference) is determined by a dip filter. Assume the attenuation level (depth) of the dip of 4. At frequency ⁇ 2, since the amplitude level difference between the target amplitude frequency characteristic (curve Cd) and the basic amplitude frequency characteristic (curve Ca) is 2.5 dB, the dip depth is assumed to be 2.5 dB first. .
- the dip sharpness (Q) is first assumed to be 40.
- the dip area is determined from the dip shape (dip shape on the amplitude frequency characteristic diagram) obtained from the assumed dip depth and sharpness.
- the amplitude frequency characteristic of the dip whose center frequency is The sex is represented by the curve C g.
- both the vertical and horizontal axes are logarithmic axes, with the vertical axis indicating amplitude level and the horizontal axis indicating frequency.
- the area of the area S2 with many parallel diagonal lines is the dip area here.
- the area of the dip obtained from the assumed dip depth and sharpness is defined as T2.
- the area T1 and the area T2 are compared. If the area T2 is equal to or greater than the area T1, the assumed attenuation level and sharpness are determined as the dip attenuation level and sharpness at the dip filter 4 removal frequency.
- the sharpness is reduced by 0.1 and the area T2 is calculated again. Then, the area T 1 and the area T 2 are compared again. If the area T 2 is equal to or greater than the area T 1, determine the attenuation level and the sharpness assumed at that time as the dip attenuation level and the sharpness at the rejection frequency of the dip filter 4. However, if the area T 2 is smaller than the area T 1, the sharpness is further reduced by 0.1, the area T 2 is obtained again, and the area T 1 and the area T 2 are compared again. Similarly, the sharpness is reduced by 0.1 until the area T2 is equal to or greater than the area T1, and the attenuation when the area T2 is equal to or greater than the area T1. Determine the level and sharpness as the dip attenuation level and sharpness at the dip fill 4 rejection frequency.
- the sharpness is not reduced and the attenuation level is reduced to the predetermined value (for example, 1.5). For example, 0.5 dB). Then, the attenuation level and the sharpness when the area T2 is equal to or greater than the area T1 are determined as the dip attenuation level and the sharpness at the removal frequency of the dip filter 4.
- the attenuation level and the sharpness at that time are determined at the rejection frequency of the dip filter 4. Determined as dip attenuation level and sharpness.
- the frequency of the second candidate frequency: f3 a similar procedure is used to determine the second rejection frequency (center frequency of the dip) to be set in the diving filter 4 and the dip attenuation level at that frequency. What is necessary is just to determine the sharpness.
- the frequencies f2 and f3 are the removal frequencies (center frequencies of the dips) to be set in the dip filter 4.
- the same procedure may be used to determine as many removal frequencies (for example, 12 removal frequencies) as can be set in the dip filter 4. Even if all rejection frequencies (for example, 12 rejection frequencies) are set as many as possible in dip filter 4, the remaining candidate frequencies that are not yet set as rejection frequencies are set in dip filter 4 as rejection frequencies. Not set.
- the frequencies f 2 and f 3 to be set as the removal frequencies in the dip filter 4 and the attenuation level (depth) and sharpness (Q) of the dip at that frequency are determined.
- these characteristics are determined as the characteristics of the dip filter 4 in the acoustic system shown in FIG. 1, resonance is prevented in the loudspeaker space 40.
- the area of the dip in the dip fill 4 is approximately the same as the area where the fundamental amplitude frequency characteristic protrudes upward from the target amplitude frequency characteristic, and in principle, the resonance frequency (the center frequency of the dip)
- the amplitude level difference between the basic amplitude frequency characteristic and the target amplitude frequency characteristic is set as the dip attenuation level of the dip filter 4.
- the sound system of FIG. 1 including the dip filter 4 set to such characteristics is set to appropriate characteristics so as to prevent resonance without deteriorating sound quality.
- the characteristic of the dip filter can be appropriately determined without requiring experience and skill, which is useful in the technical field of audio equipment.
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- Otolaryngology (AREA)
- Circuit For Audible Band Transducer (AREA)
- Tone Control, Compression And Expansion, Limiting Amplitude (AREA)
- Amplifiers (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP04714019A EP1600941B1 (en) | 2003-02-27 | 2004-02-24 | Dip filter frequency characteristic decision method |
DE602004026836T DE602004026836D1 (de) | 2003-02-27 | 2004-02-24 | Verfahren zur bestimmung der frequenzcharakteristik eines sperrfilters |
US10/547,123 US7787635B2 (en) | 2003-02-27 | 2004-02-24 | Dip filter frequency characteristic decision method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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JP2003-051147 | 2003-02-27 | ||
JP2003051147A JP3920233B2 (ja) | 2003-02-27 | 2003-02-27 | ディップフィルタの周波数特性決定方法 |
Publications (1)
Publication Number | Publication Date |
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WO2004077402A1 true WO2004077402A1 (ja) | 2004-09-10 |
Family
ID=32923359
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2004/002141 WO2004077402A1 (ja) | 2003-02-27 | 2004-02-24 | ディップフィルタの周波数特性決定方法 |
Country Status (5)
Country | Link |
---|---|
US (1) | US7787635B2 (ja) |
EP (1) | EP1600941B1 (ja) |
JP (1) | JP3920233B2 (ja) |
DE (1) | DE602004026836D1 (ja) |
WO (1) | WO2004077402A1 (ja) |
Families Citing this family (16)
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JP2006287851A (ja) * | 2005-04-05 | 2006-10-19 | Roland Corp | ハウリング防止装置 |
JP4899897B2 (ja) * | 2006-03-31 | 2012-03-21 | ソニー株式会社 | 信号処理装置、信号処理方法、音場補正システム |
US8150069B2 (en) * | 2006-03-31 | 2012-04-03 | Sony Corporation | Signal processing apparatus, signal processing method, and sound field correction system |
JP4974708B2 (ja) * | 2007-02-28 | 2012-07-11 | オンセミコンダクター・トレーディング・リミテッド | 雑音抑圧装置、受信装置 |
US8194874B2 (en) | 2007-05-22 | 2012-06-05 | Polk Audio, Inc. | In-room acoustic magnitude response smoothing via summation of correction signals |
JP4786701B2 (ja) * | 2008-12-26 | 2011-10-05 | 株式会社東芝 | 音響補正装置、音響測定装置、音響再生装置、音響補正方法及び音響測定方法 |
ES1071646Y (es) * | 2009-10-30 | 2010-06-17 | Genuix Audio S L | Dispositivo de control de calidad de megafonia |
JP2011254144A (ja) * | 2010-05-31 | 2011-12-15 | Yamaha Corp | 録音方法、この録音方法によりオーディオ信号が記録された記録媒体、およびオーディオ信号の配信方法 |
CN103636235B (zh) | 2011-07-01 | 2017-02-15 | 杜比实验室特许公司 | 用于扬声器阵列的均衡和/或低音管理的方法和装置 |
US9036825B2 (en) * | 2012-12-11 | 2015-05-19 | Amx Llc | Audio signal correction and calibration for a room environment |
JP6540090B2 (ja) * | 2015-02-25 | 2019-07-10 | 富士通株式会社 | 受信装置及び送信装置 |
WO2019183543A1 (en) | 2018-03-23 | 2019-09-26 | John Rankin | System and method for identifying a speaker's community of origin from a sound sample |
WO2020014354A1 (en) * | 2018-07-10 | 2020-01-16 | John Rankin | System and method for indexing sound fragments containing speech |
JP7184656B2 (ja) * | 2019-01-23 | 2022-12-06 | ラピスセミコンダクタ株式会社 | 故障判定装置及び音出力装置 |
US11699037B2 (en) | 2020-03-09 | 2023-07-11 | Rankin Labs, Llc | Systems and methods for morpheme reflective engagement response for revision and transmission of a recording to a target individual |
CN115060355B (zh) * | 2022-04-12 | 2024-03-26 | 东南大学 | 一种基于线性调频脉冲的谐振子品质因数测量方法 |
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- 2003-02-27 JP JP2003051147A patent/JP3920233B2/ja not_active Expired - Fee Related
-
2004
- 2004-02-24 US US10/547,123 patent/US7787635B2/en active Active
- 2004-02-24 WO PCT/JP2004/002141 patent/WO2004077402A1/ja active Application Filing
- 2004-02-24 DE DE602004026836T patent/DE602004026836D1/de not_active Expired - Lifetime
- 2004-02-24 EP EP04714019A patent/EP1600941B1/en not_active Expired - Lifetime
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JPH08130792A (ja) * | 1994-09-09 | 1996-05-21 | Yamaha Corp | ハウリング防止装置 |
JPH09275597A (ja) * | 1996-04-05 | 1997-10-21 | Sony Corp | ハウリング防止回路及び装置 |
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Title |
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See also references of EP1600941A4 |
Also Published As
Publication number | Publication date |
---|---|
EP1600941A1 (en) | 2005-11-30 |
US20060251264A1 (en) | 2006-11-09 |
EP1600941B1 (en) | 2010-04-28 |
JP2004264377A (ja) | 2004-09-24 |
JP3920233B2 (ja) | 2007-05-30 |
DE602004026836D1 (de) | 2010-06-10 |
EP1600941A4 (en) | 2008-07-16 |
US7787635B2 (en) | 2010-08-31 |
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