JPS6031400B2 - Speaker characteristics measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for measuring speaker characteristics by sweeping the frequency of an oscillator that provides a speaker drive signal to be measured over the entire frequency band necessary for measurement. It is an object of the present invention to provide a speaker characteristic measuring device that efficiently measures the characteristics of a speaker in a short time by making the measurement data sampling time interval variable according to the characteristics of the speaker.

As a related matter, when measuring speaker characteristics by sweeping the frequency over the entire frequency band required for measurement, the measurement is performed by using a sweep generator and interlocking a coder to plot the sound pressure frequency characteristics and electrical impedance characteristics. However, it is difficult to change the sweep rate at any frequency during measurement or to change the measurement data sampling time interval.

Furthermore, it took about 19 seconds to complete the measurement. Therefore,
Considering the response characteristics of the speaker under test at each measurement frequency, you can change the sweep speed of the measurement frequency, increase the sweep speed in frequency bands where the data is not very important, and shorten the overall measurement time. It is difficult to change the sampling time interval during measurement to collect only data at the necessary frequency points, and it is difficult to efficiently measure speaker characteristics in a short period of time. The present invention eliminates the above-mentioned conventional drawbacks and provides a speaker characteristic measuring device that measures speaker characteristics efficiently in a short time by making the frequency sweep speed and data sampling time interval variable at any frequency during speaker characteristic measurement. This will be explained below with reference to the drawings.

FIG. 1 is a block diagram of main parts of a first embodiment of the present invention. In the figure, 1 is an oscillator that can change the frequency sweep speed based on the control data from the control circuit 8, 2 is an amplifier for amplifying the signal of the oscillator 1 and feeding it to the speaker under test 4, and 3 is an audio 4 is a speaker to be measured; 5 is a microphone; 6 is a measurement amplifier for amplifying the output of the microphone 5; 7 is a control circuit 8;
a sound pressure data sampling circuit that samples and holds sound pressure data using a data sampling signal S from the
8 is a control circuit that controls the sweep speed of the oscillator 1 and the data sampling time interval of the sound pressure data sampling circuit 7 based on the data that controls the sweep speed of the oscillator 1 and the data sampling signal S set in the memory circuit 9; , 9 is a storage circuit that holds data for controlling the sweep speed of the oscillator 1 and the data sampling signal S. Next, the operation of the embodiment shown in FIG. 1 will be explained.

As control data for the oscillator 1, data for causing oscillation at time ti with frequency fi and sweep speed i (i=1 to 5) and sound pressure data sampling circuit 7 are provided.
As the control data, data such that the data sampling time interval is Ti (i = 1 to 5) at the frequency fi is used.
A storage circuit 9 stores data for generating a data sampling signal S.
The control data is sequentially taken into the control circuit 8 when measuring speaker characteristics, and the data is used to control the oscillation frequency and sweep speed of the oscillator 1, and at the same time control the data sampling time interval of the sound pressure data sampling circuit 7. . This operation will be explained with reference to FIGS. 2a and 2b. At the same time, the oscillator frequency also oscillates at the sweep speed according to the control data from the control circuit 8. The transmitted signal is amplified by the amplifier 2, and the speaker under test 4 is operated. The sound waves emitted by this operation are captured by the microphone 5 and converted into electrical signals. The signal is amplified by a measurement amplifier 6 and guided to a sound pressure data sampling circuit 7. The signal is sampled at time intervals T by a data sampling signal S from the control circuit 8 and used by the user. The process is repeated until the oscillator 1 emits the maximum frequency fM required for the measurement, and the measurement is completed immediately after the oscillator 1 emits the frequency fM. Second
In the figure, the wavelength of the signal wave from the oscillator 1 is long from the low frequency frequency f, to f2, and it takes some time for the speaker under test 4 to respond sufficiently, so the measured data sampling time interval T, is The frequency sweep speed is relatively small. On the contrary, the wavelength of the signal wave from the oscillator 1 is short from the high frequency frequency to fM, and it does not take much time for the speaker 4 to be measured to respond sufficiently. Therefore, in this frequency band, the measurement data sampling time interval T5 is relatively small, and the frequency sweep rate H5 is relatively large. Furthermore, from frequencies f3 to f4, the measurement data sampling time interval T3 is shortened slightly, and the frequency sweep interval T3 is made relatively small, giving high frequency resolution to the measurement data. As described above, this speaker characteristic measuring device makes measurements that take into account the response characteristics of the speaker under test at each measurement frequency by making the frequency sweep speed and measurement data sampling time interval variable at any frequency during measurement. In addition to improving the reliability of measurement data, it is possible to shorten the overall measurement time by increasing the frequency sweep speed at frequencies other than the frequency band where frequency resolution is particularly required, and to measure the measurement data sampling time interval. It is possible to collect data only at the necessary frequency points by changing the frequency range, providing highly reliable measurement data, and being able to measure speaker characteristics in a short time.It is extremely efficient and waste-free. It can provide new functions not found in conventional measuring devices of this type, such as the ability to perform measurements.

By the way, it is also possible to consider an apparatus that can measure the electrical impedance characteristics at the same time as measuring the sound pressure frequency characteristics of the speaker to be measured.

FIG. 3 is a block diagram of main parts of a second embodiment of the present invention. In this embodiment, an impedance measuring circuit 10 that measures the electrical impedance of the speaker under test 4 and an impedance data sampling circuit 11 that samples the output data of the measuring circuit using a data sampling signal S are added to the circuit configuration shown in FIG. This is what I did. By adopting such a circuit configuration, it is possible to simultaneously measure the sound pressure frequency characteristics and electrical impedance characteristics of the speaker under test 4, and also to control the frequency sweep speed and measurement data sampling at any frequency within the measurement frequency band. Since the time intervals can be controlled by the control data stored in the storage circuit 9, the same effects as described in the operational description of the embodiment of FIG. 1 are obtained with respect to both the sound pressure frequency characteristic and the electrical impedance characteristic measurements.

An example of this effect will be explained with reference to FIG. 4. In the figure, f and fM represent the minimum frequency and maximum frequency required for measurement, respectively, SPL represents sound pressure, Z represents electrical impedance, and f. represents the lowest resonant frequency. In SPL, the frequencies fp and fq
A peak and a dip are observed between the frequencies fp and fq, and in order to accurately detect the peak and the dip, high frequency resolution is required between the frequencies fp and fq. Moreover, in Z, the lowest resonant frequency f. A single peak characteristic was observed nearby, and this situation was detected and f. In order to accurately obtain the value of , high frequency resolution is required between frequencies fa and fb. Therefore, when measuring such data, the oscillator 1 and the data sampling signal are adjusted to keep the frequency sweep speed and measurement data sampling time interval as small as possible between frequencies fa and fb and between frequencies fp and fq. Control data for controlling S may be stored in the storage circuit 9.

The method described above is to perform measurement while controlling the oscillator 1 and the data sampling signal S according to the control data stored in advance in the storage circuit 9. However, depending on the situation of the measurement data, the frequency sweep speed and the measurement data A method of performing measurements while controlling the sampling time interval is also conceivable.

FIG. 5 is a block diagram of main parts of a third embodiment of the present invention.

In this embodiment, the impedance data from the impedance data sampling circuit 11 is compared with the impedance data at the previous measurement point stored in the storage circuit 9 using the circuit configuration shown in FIG. 3, and the state of the impedance curve is detected. An impedance data comparison circuit 12 is added to the control circuit 8 to send out a signal Cz for controlling the impedance data sampling time interval, and the data sampling signal is added to the sound pressure data sampling signal S.
p and impedance data sampling signal Sz, Sp is controlled by control data stored in advance in the storage circuit 9, similar to the operation in FIG. 3, and Sz is controlled by the signal Cz. Therefore, the operation for measuring sound pressure data is exactly the same as that shown in FIG. 3, but the measurement for impedance data is different from that shown in FIG. 3, so it will be explained using FIG. 5. In response to the impedance data sampling signal Sz from the control circuit 8, the impedance data at the current measurement time is sent from the impedance data sampling circuit to the storage circuit 9 and the impedance data comparison circuit 12. The impedance data at the point is sent to the comparison circuit 12, and these two impedance data are compared by the comparison circuit 12 to detect the state of the impedance curve at the time of measurement. A signal C that controls the impedance data sampling signal Sz from the comparison circuit 12 to the control circuit 8 according to the detection result.
z is sent out and the next impedance data sampling time interval is determined. This process is repeated from the minimum frequency to the maximum frequency required for measurement, and the electrical impedance characteristics are measured. By adopting such a configuration, in addition to the effects described in the description of the second embodiment, it is possible to efficiently sample impedance data according to the electrical impedance characteristics of the speaker to be measured.

In addition, the measurement of impedance data according to this embodiment is limited to a region where frequency resolution is required (for example, the region near the lowest resonance frequency f), and the measurement of impedance data according to the second embodiment is used for other frequencies. It is also possible to easily perform measurements by employing the configuration described above. By the way, the lowest resonant frequency f of the speaker under test.

To find f, use the measurement method described above. Measurement is performed by increasing the frequency resolution in the vicinity, and from the measurement results f. In such a method, f. The accuracy of is determined by the frequency resolution in measurement, and it is not possible to increase the accuracy further. Therefore, f. f using an interpolation method from nearby impedance data values. A method can be considered to obtain accurately. FIG. 6 is a block diagram of the main parts of a fourth embodiment of the present invention based on such an idea.

In this embodiment, the lowest resonant frequency f is determined using the interpolation method from the measured impedance data in the circuit configuration shown in FIG. An arithmetic circuit 13 for calculating is added. below,
In the circuit of FIG. 6, the lowest resonant frequency f. We will explain the operation to find . Impedance data is sequentially sampled by a data sampling signal S from the control circuit 8 and sequentially stored in the storage circuit 9. From among these impedance data, the control circuit 8 calculates an impedance peak value Zj, a frequency fj that gives the peak value, and a measurement frequency fj- which is one point before the frequency fj.
, the impedance value Zj-, and the frequency fj-
, , the impedance value Zj+ at fj+, which is the measurement frequency after one point of frequency fj, and the frequency fM are sent to the arithmetic circuit 13, and the arithmetic circuit receives these six data fi-,, fi, fi+. ,Zi-・,Zi,Zi ten,
The lowest resonant frequency f by interpolation method using. Calculate. The interpolation method is as shown in FIG. A nearby impedance curve is approximated to a quadratic curve, and the frequency that gives the peak value of the curve is calculated from the following equation, and the frequency is set to f. That is. f. =Kyo (F-D counterattack fast air)...
{11 However, A=fj−. −fj+,
…[21B=fj-, one fj
...is iC=fj-fj ten,
…[4}D=Zj-,-Zj
…[5}E=Zj−Zp,
…[61F=fj-, 10fj
...(7}).

In the figure, the solid line represents the impedance curve, and the dotted curve 1 is f.

It represents a quadratic curve that approximates a nearby impedance curve. As mentioned above, f on the frequency axis. Neighborhood Adjacent 3
f using an interpolation method from point impedance data. By adding a function to accurately obtain f, from the point of view of impedance data measurement. There is no need to increase the frequency resolution of measurements in the vicinity, and f. It is possible to increase the frequency sweep speed at nearby frequencies as much as possible to shorten the overall measurement time. This is very effective when it is desired to measure the characteristics of as many speakers as possible within a limited time. In the above embodiment, the frequency is continuously swept from the minimum frequency to the maximum frequency necessary for measurement, and data at the required frequency points are extracted using the data sampling signal. It is also possible to consider a method of oscillating frequencies only at frequency points where data is needed, sweeping discretely, and extracting data at those frequency points, instead of sweeping the data.

FIG. 8 is a block diagram of a main part of a fifth embodiment of the present invention that incorporates such an idea.

In this embodiment, the signal line for the data sampling signal S, the sound pressure data sampling circuit 7, and the impedance data sampling circuit 11 are removed from the circuit configuration shown in FIG. When given oscillation time data (which corresponds to the data sampling time interval), the programmable oscillator 14 performs the required oscillation according to the data.
It was replaced with The oscillation frequency data and oscillation time data of the frequency at a frequency point for which measurement data is required are stored in advance in the storage circuit 9, and when measuring speaker characteristics, the control circuit 8 sequentially stores the oscillation frequency data and the oscillation time data from the storage circuit 9. The oscillation time data is extracted, the programmable oscillator 14 is operated using the data, the frequency is discretely swept over the entire frequency band required for measurement, and the sound pressure frequency characteristics and electrical impedance characteristics are measured. Even in measurement using such a measurement method, exactly the same effect as the measurement using the circuit configuration of the embodiment shown in FIG. 3 can be obtained. A brief explanation of the drawing. FIG. 1 is a block diagram of the first embodiment of the present invention;
Figures a and b are frequency sweep operation explanatory diagrams for explaining the effects of the embodiment of Figure 1, Figure 3 is a block diagram of the main part of the second embodiment of the present invention, and Figure 4 is the diagram of Figure 3. Figures 5 and 6 are block diagrams of main parts of the third and fourth embodiments of the present invention; FIG. 7 is a diagram illustrating the application method of the interpolation method for determining the lowest resonant frequency in the embodiment of FIG. 6, and FIG.
FIG. 2 is a block diagram of main parts of an embodiment of the present invention.

1... Oscillator, 2... Amplifier, 3... Measurement pupil body, 4... Speaker to be measured, 5... Microphone, 6... Measurement amplifier, 7 ...Sound pressure data sampling circuit, 8...Control circuit, 9...
... Memory circuit, 10 ... Impedance measurement circuit, 11 ... Impedance data sampling circuit, 12 ... Impedance data comparison circuit,
13... Arithmetic circuit, 14... Programmable oscillator.

Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 4 Figure 7 Figure 8

Claims (1)

[Scope of Claims] 1. A device for measuring speaker characteristics by sweeping the frequency of an oscillator from a required minimum frequency to a maximum frequency, the frequency sweep rate and the measurement data sampling time interval being set to the frequency of the speaker under test. A speaker characteristic measuring device characterized by comprising a control means that varies according to the characteristics. 2. In the description of claim 1, the control means includes an electrical impedance measuring circuit for the speaker to be measured and an impedance data sampling circuit for sampling output data of the impedance measuring circuit, and The frequency sweep speed of the oscillator that provides a signal to the speaker under test and the measurement data sampling time interval can be made variable according to the frequency resolution and measurement data sampling time interval required for sound pressure frequency characteristic data and impedance characteristic data. A speaker characteristic measuring device comprising: 3. In the description of claim 2, the control means further includes an impedance data comparison circuit that compares impedance data at two points on the frequency axis, and A speaker characteristic measurement characterized in that it is configured to detect the state of the impedance curve at the time of measurement by comparison with a comparison circuit, and to control the frequency sweep speed and the data sampling time interval based on the detection result. Device. 4. In the description of claim 2, the control means further includes an arithmetic circuit that calculates the lowest resonance frequency f_o from the measured impedance data using an interpolation method, and the control means further includes an arithmetic circuit that calculates the lowest resonant frequency f_o from the measured impedance data, and the control means further includes an arithmetic circuit that calculates the lowest resonance frequency f_o from the measured impedance data, and A speaker characteristic measuring device characterized in that the frequency sweep speed is increased by determining the value of f_o by the arithmetic circuit using an interpolation method from the value of the impedance data.