JPH09130897A - Inspecting device for electroacoustic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply detect abnormality in a speaker by saving labor and time. SOLUTION: A bridge circuit is formed by speaker units 3 and 3 serially connected to a speaker line 4 and resistors 5 and 5 to supply AC signal to this from a signal generator 1 through an amplifier 2. In addition the bridge circuit keeps its balance when both of the speaker units 3 and 3 are normal. Consequently, when abnormality is generated in either speaker unit 3, the balanced state of the bridge circuit is lost so that a potential difference V is generated (VA≠VE) in the input of a differential amplifier 6 to turn on light emitting diodes 7 and 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroacoustic apparatus having a plurality of loudspeakers, and an inspection apparatus for inspecting the abnormality of the above-mentioned loudspeakers. The present invention relates to an inspection device.

[0002]

2. Description of the Related Art Generally, a failure of a speaker, for example, a speaker unit is often a disconnection or a short circuit of a voice coil.
There is something like that shown in In the inspection apparatus shown in the figure, a signal in the audio band, for example, a signal of 1 kHz is input from a signal generator 1 to a speaker unit 3 to be inspected via an amplifier 2 and output from the speaker unit 3. The output sound is picked up by the microphone 101, and the output is monitored by the measuring instrument 102 such as a voltmeter or an oscilloscope.

That is, when an abnormality such as disconnection or short circuit occurs in the voice coil of the speaker unit 3, the microphone 101
Output level becomes zero, or speaker unit 3
Becomes a level smaller than that in the normal state, and therefore the abnormality of the speaker unit 3 can be detected by monitoring this with the measuring instrument 102.

[0004]

However, when the electroacoustic apparatus is provided with a plurality of speaker units 3, according to the above-mentioned conventional technique, all the speaker units 3 undergo the above-described inspection one by one. However, there is a problem that it is very troublesome and troublesome.

Also, an abnormality occurs in the speaker unit 3,
Therefore, even if the output level of the microphone 101 is reduced, the abnormality of the speaker unit 3 cannot be detected unless the output level of the microphone 101 when the speaker unit 3 is normal is recognized in advance. There is also. Furthermore, the microphone 101
Since relatively expensive inspection equipment such as the measuring instrument 102 and the measuring instrument 102 is used, the equipment cost is also required.

Therefore, an object of the present invention is to provide an inspection apparatus for an electroacoustic apparatus capable of detecting an abnormality in the speaker unit 3 without the trouble of the above-mentioned prior art. It is also an object of the present invention to realize the above inspection device with a relatively simple configuration without using inspection equipment such as the microphone 101 and the measuring instrument 102.

[0007]

In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention comprises a plurality of speakers connected in series to a speaker line and an alternating current to the speaker line. The test signal supply means for supplying the test signal of 1., the voltage dividing means for dividing the potential difference between both ends of the column formed by the speaker at a predetermined ratio, and the potential obtained by the voltage dividing by the voltage dividing means and the speaker. And a potential difference detecting means for detecting a difference from a potential at a predetermined intermediate point of the column and outputting a detection signal having a level according to the potential difference.

That is, a bridge circuit is formed by the speakers connected in series and the voltage dividing means. Therefore, when an abnormality occurs in any of the speakers (for example, the voice coil is disconnected or short-circuited), the impedance of the series circuit formed by the speakers changes, which causes a change in the potential difference, that is, the level of the detection signal.

According to a second aspect of the present invention, in the electroacoustic apparatus inspection apparatus according to the first aspect, when the speakers are all operating normally, the potential difference is substantially zero. It is characterized by that.

That is, the fact that the potential difference becomes substantially zero when all the speakers are in a normal state means that the bridge circuit is in a balanced state. Therefore,
When an abnormality occurs in any of the speakers, the equilibrium state of the bridge circuit is lost, so the potential difference becomes a value other than substantially zero. That is, it is possible to detect whether or not the speaker is abnormal, depending on whether or not the detection signal having a level corresponding to the potential difference is substantially zero.

According to a third aspect of the present invention, in the electroacoustic apparatus inspection apparatus according to the second aspect, the potential difference detecting means causes the detection signal to be substantially zero when the absolute value of the potential difference is equal to or less than a predetermined value. It is characterized in that it is configured in the following state.

That is, if the absolute value of the potential difference is less than or equal to a predetermined value, it is considered that the bridge circuit is in a balanced state, that is, it is considered that no abnormality has occurred in the speaker.

The invention described in claim 4 is the invention according to claim 2 or 3.
In the electroacoustic apparatus inspection apparatus described in (1), an output means for outputting one or both of the visible information and the audible information according to the detection signal is provided.

That is, when an abnormality occurs in the speaker, one or both of visible information, that is, display and audible information, that is, sound is output.

According to a fifth aspect of the present invention, in the electroacoustic apparatus inspection apparatus according to the fourth aspect, the output means comprises:
It is characterized by being formed by one or both of a light emitting diode and a buzzer.

That is, the abnormality of the speaker can be detected by one or both of the lighting of the light emitting diode and the alarm of the buzzer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of an inspection apparatus for an electroacoustic apparatus according to the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 shows this inspection device, for example,
It is a figure which shows schematic structure at the time of applying to the electroacoustic apparatus which has the speaker units 3 and 3 of a stand.

As shown in the figure, the speaker unit 3,
3 is connected in series to a speaker line 4 wired on the output side of the amplifier 2 (on the right side in the figure). The speaker units 3 and 3 have the same characteristics. For example, in a speaker system in which two speaker units of the same standard are provided in one speaker box, the speaker units 3 and 3 are connected in series. It

A signal generator 1 for generating an AC signal in the voice band, for example, a signal of 1 kHz is connected to the input side of the amplifier 2 (on the left side of FIG. 1).
The signal output from the amplifier 2 and the speaker line 4
It is configured to be supplied to each speaker unit 3, 3 via. The signal generator 1 corresponds to the inspection signal output means described in the claims, and the 1 kHz signal output from the signal generator 1 corresponds to the inspection signal.

A resistor series circuit 50 is connected in parallel with the series circuit formed by the speaker units 3 and 3. The resistor series circuit 50 is, for example, one in which two resistors 5 and 5 of the same standard are connected in series.

Further, 2 which constitutes the resistor series circuit 50.
A connection point A connecting the two resistors 5 and 5 is, for example, OP
It is connected to one input terminal of the differential amplifier 6 composed of an amplifier, for example, a non-inverting input terminal (+). That is, a voltage (amplifier 2) applied between both ends of the speaker units 3 and 3 by the resistors 5 and 5 is applied to the non-inverting input terminal (+).
The voltage V _{A obtained} by dividing the output voltage V) of V is supplied. The resistor series circuit 50 corresponds to the voltage dividing unit described in the claims.

On the other hand, the inverting input terminal (-) of the differential amplifier 6 (OP amplifier) is connected to the intermediate point (connection point connecting the speaker units 3 and 3) B of the series circuit of the speaker units 3 and 3. ing. That is, the inverting input terminal (-), the voltage V _B that the voltage V divided by the impedance of the speaker units 3 itself is supplied. As can be seen from the connection configuration of the speaker units 3 and 3 and the resistors 5 and 5, they form a bridge circuit.

The differential amplifier 6 has a potential difference between the voltages V _A and V _B supplied from the bridge circuit (that is, a potential difference between the connection points A and B) ΔV (ΔV = V _A -V).
_B ) is detected and a voltage E having a polarity and a level corresponding to this potential difference ΔV is output. That is, the differential amplifier 6 has the input / output characteristics as shown in FIG. The differential amplifier 6 corresponds to the potential difference detecting means described in the claims.

Further, the output of the differential amplifier 6 is connected to the anode of the light emitting diode 7 and the cathode of the light emitting diode 8, and the cathode of the light emitting diode 7 and the anode of the light emitting diode 8 are connected to respective bias resistors. It is grounded via devices 9 and 10. That is, when the voltage E output from the differential amplifier 6 has a positive polarity, the light emitting diode 7 lights up, and when the voltage E has a negative polarity, the light emitting diode 8 lights up. The light emitting diodes 7 and 8 correspond to the output means described in the claims.

In the electroacoustic apparatus inspection apparatus configured as described above, when both speaker units 3 and 3 are normal (when there is no abnormality), the speaker units 3 and 3 have the same characteristics. Therefore, each impedance is equal. Further, since the resistors 5 and 5 are of the same standard, the bridge circuit formed by the speaker units 3 and 3 and the resistors 5 and 5 is in a balanced state. Therefore, when a signal is supplied from the signal generator 1 to the speaker units 3 and 3 via the amplifier 2 and the speaker line 4 in this state, the voltage V _{A at the} connection point _A and the voltage V _{B at the} connection point _B are both The value is half the voltage V applied across the series circuit of the units 3 and 3 (V _A = V _B = (1/2) V). That is, connection point A
And the potential difference [Delta] V between the B zero _{(ΔV = V A -V B =} 0) becomes, since even zero (E = 0) the output voltage E of the differential amplifier 6, both light emitting diodes 7 and 8 does not emit light .

When an abnormality such as a disconnection or short circuit of the voice coil occurs in either one of the speaker units 3 and 3, the impedance of the speaker unit 3 on the side where the abnormality occurs changes. This breaks the balanced state of the bridge circuit, so that the voltage V _{A at} the connection point A on the resistors 5 and 5 side is V _A = (1/2) V, which is the same as the above, while the speaker unit 3, The voltage V _{B at} the connection point B on the third side becomes V _B ≠ (1/2) V, and the connection points A and B are
The potential difference [Delta] V is generated between _{(ΔV = V A -V B ≠} 0). Then, a voltage E (E ≠ 0) having a polarity and a level corresponding to the potential difference ΔV is output from the differential amplifier 6, and thereby the light emitting diodes 7 and 8 are turned on (specifically, depending on the level of the voltage E). And the brightness is alternately turned on (blinking) according to the frequency (1 kHz) of the output signal of the signal generator 1 described above).

Even if an abnormality occurs in both of the speaker units 3, 3, both speaker units 3,
As long as the impedances of 3 do not match, the above-mentioned balanced state of the bridge circuit cannot be maintained. Therefore, in this case as well,
The light emitting diodes 7 and 8 are turned on (blinking) in the same manner as above.

As described above, according to the first embodiment, the light emitting diodes 7 and 8 are turned on when an abnormality such as disconnection or short circuit of the voice coil occurs in any of the speaker units 3 and 3. That is, it is possible to confirm whether or not any abnormality has occurred in the speaker units 3 and 3 depending on whether or not the light emitting diodes 7 and 8 are lit.
Therefore, unlike the above-described related art, it is not necessary to inspect each of the speaker units 3 and 3 one by one, so that the speaker units can be easily and efficiently compared to the above-described related art without much trouble. Three or three abnormalities can be detected.

Further, since it is only necessary to confirm the lighting state of the light emitting diodes 7 and 8, it is necessary to previously recognize the output level of the microphone 101 when the speaker unit 3 is in a normal state, or It is easier to detect an abnormality in the speaker units 3 and 3 as compared with the above-mentioned conventional technique in which the measuring device 102 such as a voltmeter or an oscilloscope has to be monitored. Further, since the measuring device 102 such as a voltmeter or an oscilloscope is not used, the cost of the inspection device can be reduced.

In the first embodiment, the state of the speaker units 3 and 3 is confirmed by checking the lighting state of the light emitting diodes 7 and 8. However, the present invention is not limited to the light emitting diodes 7 and 8, and may be, for example, a light bulb. Other display components or display devices such as the above may be used. Further, the number of light emitting diodes 7 and 8 is not limited to two. Then, the speaker units 3, 3
The abnormality may be detected not by visual information that the light emitting diodes 3 and 3 are turned on, but by voice, that is, audible information by using a voice output component or device such as a buzzer. Further, similarly to the above-mentioned conventional technique, the output voltage of the differential amplifier 6 is measured using a measuring instrument such as a voltmeter or an oscilloscope, and the abnormality of the speaker units 3 and 3 is detected from the measured value. It may be configured as follows.

Further, although the two resistors 5 and 5 are used to divide the voltage V applied between both ends of the speaker units 3 and 3, it is divided using two or more resistors. Good. The voltage V may be divided not only by the resistors 5 and 5, but also by other components such as a coil. Furthermore, the voltage dividing ratio of the voltage V may be variable by using a variable resistor or the like.

Although the differential amplifier 6 is composed of an OP amplifier, it may be composed of a transistor. Further, although the connection point A is connected to the non-inverting input terminal (+) and the connection point B is connected to the inverting input terminal (−) of the differential amplifier 6, this connection relationship may be reversed. Further, the level of the voltage E output from the differential amplifier 6 is set to a level corresponding to the potential difference ΔV between the connection points A and B, but the level is not limited to this, and the above potential difference ΔV occurs, for example. In this case, the voltage E may be set to a certain level.

Further, from the signal generator 1 to the speaker line 4
The inspection signal to be supplied to is an AC signal having a frequency in the voice band, for example, 1 kHz, but is not limited to this, and may be a voice signal or a music signal, or may be an AC signal having a frequency outside the voice band. .

Further, in FIG. 1, the speaker units 3 and 3 are
Although the same standard, that is, the one having the same characteristic is shown as above, the invention is not limited to this, and those having different characteristics may be used. In such a case, if the resistors 5 and 5 have the same characteristics, the bridge circuit cannot maintain the equilibrium state even when the speaker units 3 and 3 are both normal, and the potential difference ΔV between the connection points A and B is ΔV. Is no longer zero (ΔV ≠
0). When an abnormality occurs in the speaker units 3 and 3 in this state, the value of the potential difference ΔV becomes a value different from that in the normal state. Therefore, the abnormality of the speaker units 3 and 3 can be detected by detecting the change in the potential difference ΔV.

Further, in the first embodiment,
Although the inspection device for the electro-acoustic apparatus having the two speaker units 3 and 3 has been described, for example, as shown in FIG. 3, two or more (seven in the figure) speaker units 3, 3, ... This inspection apparatus can also be applied to an electroacoustic apparatus having a.

Also in this case, similarly to FIG. 1 described above, the resistor series circuit 50 is connected in parallel to the series circuit of each speaker unit 3, 3, ... To form a bridge circuit. In this resistance series circuit 50, for example, resistors 5, 5, ... Of the same standard are connected in series by the same number (7) as the speaker units 3, 3 ,. The connection points A and B are set so that, for example, the bridge circuit is in a balanced state when all the speaker units 3, 3, ... Are in a normal state. With this configuration, either speaker unit 3,
The light emitting diodes 7 and 8 can be made to emit light only when abnormality occurs in 3, ... In addition, the number of the resistors 5, 5, ...
Needless to say, it does not have to be the same number as.

Further, not limited to the speaker units 3 and 3,
For example, as shown in FIG. 4, a multi-way speaker system including a dividing network 31 (a woofer 32, a squawker 33, and a tweeter 34 in the figure).
Is provided in one speaker box 35 together with the dividing network 31).
The present inspection apparatus can also be applied to an electroacoustic apparatus having a plurality of (two in the figure).

In this case, the speaker units 3 and 3 in FIG.
The signal from the signal generator 1 to the speaker line 4 is replaced with 0, and a signal, for example, white noise, which uniformly contains the frequency components of the respective reproduction bands of the woofer 32, the squawker 33 and the tweeter 34 which constitute the multi-way speaker system 30. It may be configured to supply to. With this configuration, when an abnormality occurs in any of the woofer 32, the squawker 33, or the tweeter 34, a potential difference ΔV is generated between the connection points A and B, and the light emitting diodes 7 and 8 are turned on, thereby detecting the abnormality. be able to.

Next, a second embodiment of the inspection device according to the present invention will be described with reference to FIGS. FIG.
FIG. 1 is a schematic configuration diagram of this inspection device. As shown in the figure, this inspection device is the same as the inspection device of FIG. 1 described above, with a non-linear circuit 11 interposed between the differential amplifier 6 and the light emitting diodes 7 and 8. Since the other configurations are the same as those of the inspection apparatus of FIG. 1, the same reference numerals are given to the same portions, and detailed description thereof will be omitted.

That is, the nonlinear circuit 11 includes the diode 12
And a series combination circuit 15 in which a DC power supply 13 and a resistor 14 are connected in series, and a series combination circuit 19 formed by connecting a diode 16, a DC power supply 17 and a resistor 18 in series are connected in antiparallel. It was done. The cathodes of the diodes 12 and 16 of the series combination circuits 15 and 19 are connected to the anode sides of the DC power supplies 13 and 17, respectively. The cathode sides of the DC power supplies 13 and 17 are connected to the respective ends of the resistors 14 and 18, respectively. The anode of the diode 12 of the series combination circuit 15 and the other end of the resistor 18 forming the series combination circuit 19 are connected to the output of the differential amplifier 6. Further, the other end of the resistor 14 forming the series combination circuit 15 and the anode of the diode 16 of the series combination circuit 19 are connected to the anode of the light emitting diode 7 and the cathode of the light emitting diode 8. Further, the output voltage values E ₁₃ and E ₁₇ of the DC power supplies ₁₃ and ₁₇ are variable.

In the inspection device configured as described above, when the output voltage E of the differential amplifier 6 has a positive polarity, the output current flows through the series combination circuit 15 and the light emitting diode 7. At this time, the voltage E ₀ supplied to the light emitting diode 7 is the output voltage E of the differential amplifier 6, the forward voltage E ₁₂ of the diode ₁₂ and the reverse voltage E _{13 of the} DC power supply _13.
It is the voltage value minus the voltage drop due to. Therefore, in order to supply the voltage E ₀ to the light emitting diode 7, at least the absolute value of the output voltage E of the differential amplifier 6 is equal to the forward voltage E ₁₂ of the diode ₁₂ and the reverse voltage E ₁₃ of the DC power supply 13. Must be greater than the absolute value of the sum (| E |> |
E ₁₂ + E ₁₃ |).

On the contrary, when the output voltage E of the differential amplifier 6 has a negative polarity, its output current is as follows:
9 and the light emitting diode 8. In this case, the voltage E ₀ supplied to the light emitting diode 8 is a voltage obtained by subtracting the voltage drop due to the reverse voltage E ₁₇ of the DC power supply ₁₇ and the forward voltage E ₁₆ of the diode 16 from the output voltage E of the differential amplifier 6. It becomes a value. Therefore, in order to supply the voltage E ₀ to the light emitting diode 8, at least the absolute value of the output voltage E of the differential amplifier 6 is equal to the reverse voltage E ₁₇ of the DC power supply ₁₇ and the forward voltage E ₁₆ of the diode 16. It must be greater than the absolute value of the sum (| E |> | E ₁₇ + E ₁₆ |).

That is, in the inspection apparatus shown in FIG. 5, by adding the non-linear circuit 11, the input of the differential amplifier 6, that is, the potential difference ΔV and the light emitting diodes 7 and 8 are provided.
The relationship with the voltage E ₀ supplied to the circuit is as shown in FIG. Therefore, even if there is a potential difference ΔV at the input of the differential amplifier 6, the light emitting diodes 7 and 8 do not emit light unless the absolute value thereof is larger than the absolute value of the predetermined value Δ ₁ or Δ ₂ shown in FIG. The predetermined values Δ ₁ and Δ ₂ are
It can be varied by the reverse voltage E _{13 of} the DC power supply ₁₃ and the reverse voltage E ₁₇ of the DC power supply.

Therefore, if there is an error in the characteristics (mainly impedance) between the speaker units 3 and 3 of the same standard, or there is a difference in characteristics between the speaker units 3 and 3 due to deterioration over time. Even if the equilibrium state of the bridge circuit is broken due to the above, if the absolute value of the potential difference ΔV is equal to or smaller than the predetermined value Δ ₁ or Δ ₂ , it is considered that the equilibrium state of the bridge circuit is maintained. That is, it is considered that the speaker unit 3 has no abnormality. This applies not only to the speaker units 3 and 3, but also to the case where the balanced state of the bridge circuit collapses due to an error in resistance values of the resistors 5 and 5 and deterioration with time.

As described above, according to the second embodiment, the change in the characteristics due to the characteristic error between the speaker units 3 and 3 and between the resistors 5 and 5 and the deterioration with time is absorbed. The effect is that you can.

Although the forward voltage of the light emitting diodes 7 and 8 is not particularly mentioned in the second embodiment, when the respective light emitting diodes 7 and 8 are turned on, the forward voltage is exceeded. It goes without saying that the forward voltage of each of the light emitting diodes 7 and 8 must be taken into consideration, such as the fact that the voltage E ₀ must be applied.

In addition, the DC power supplies 13 and 1 of the nonlinear circuit 11
Instead of 7, a Zener diode may be used. In this case, the anode side of the Zener diode corresponds to the anode side of the DC power supplies 13 and 17, and the cathode side corresponds to the cathode side of the DC power supplies 13 and 17. The characteristics shown in FIG. 6 may be realized by a circuit configuration other than the nonlinear circuit 11.

[0048]

According to the first aspect of the present invention, when an abnormality such as disconnection or short circuit of the voice coil occurs in any of the speakers, the level of the detection signal output by the potential difference detecting means changes. That is, the abnormality of the speaker can be detected by capturing the change in the level of the detection signal. Therefore, unlike the above-described conventional technology, it is not necessary to perform the inspection for all the speakers one by one, so that it is possible to perform the inspection of the speaker easily and efficiently, with less effort than the conventional case. There is.

According to the second aspect of the present invention, it is possible to detect whether or not the speaker is abnormal, depending on whether or not the level of the detection signal output by the potential difference detecting means is substantially zero. Therefore, unlike the prior art in which the output level of the microphone 101 when the speaker is in a normal state must be recognized in advance,
There is an effect that it is not necessary to purposely recognize the level of the detection signal when the speaker is normal.

According to the third aspect of the invention, when the absolute value of the potential difference is less than or equal to the predetermined value, it is considered that the speaker is not abnormal. Therefore, even if the characteristics (impedance) differ between the speakers due to, for example, deterioration of each speaker over time, and thus the equilibrium state of the bridge circuit is disrupted and the potential difference changes, the absolute value of the difference is the predetermined value. If it is less than or equal to the value, it is considered that no abnormality has occurred in the speaker. That is, there is an effect that it is possible to absorb the characteristic difference between the speakers caused by the above-described deterioration with time.

According to the invention described in claim 4, when an abnormality occurs in the speaker, one or both of the display and the sound are output. Therefore, there is an effect that the abnormality of the speaker can be detected much more easily as compared with the above-described conventional technique in which the abnormality of the speaker is detected by monitoring the measuring device 102 such as a voltmeter or an oscilloscope.

According to the fifth aspect of the invention, the abnormality of the speaker can be detected by one or both of the lighting of the light emitting diode and the alarm of the buzzer. Therefore, there is an effect that this inspection device can be constructed at a very low cost as compared with the above-mentioned conventional technique which uses relatively expensive inspection equipment such as the microphone 101 and the measuring instrument 102.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an inspection apparatus for an electroacoustic apparatus according to the present invention.

FIG. 2 is an input / output characteristic diagram of the differential amplifier according to the same embodiment.

FIG. 3 is a diagram showing an application example of the embodiment.

FIG. 4 is a diagram showing an application example different from FIG.

FIG. 5 is a schematic configuration diagram showing a second embodiment of an inspection apparatus for an electroacoustic apparatus according to the present invention.

FIG. 6 is a graph showing the relationship between the input of the differential amplifier and the voltage supplied to the light emitting diode in the same embodiment.

FIG. 7 is a schematic configuration diagram showing a conventional inspection apparatus for an electroacoustic apparatus.

[Explanation of symbols]

 1 Signal Oscillator 2 Amplifier 3 Speaker 4 Speaker Line 5 Resistor 6 Differential Amplifier 7, 8 Light Emitting Diode 50 Resistor Series Circuit

Claims (5)

[Claims] 1. A plurality of speakers connected in series to a speaker line, a test signal supply means for supplying an AC test signal to the speaker line, and a potential difference between both ends of a row formed by the speaker at a predetermined ratio. A voltage dividing means for dividing the voltage and a difference between the potential obtained by the voltage dividing by the voltage dividing means and the potential at a predetermined intermediate point of the row formed by the speaker is detected, and a detection signal having a level corresponding to the potential difference is output. An inspection apparatus for an electroacoustic apparatus, comprising: a potential difference detection means. 2. The electroacoustic apparatus inspection apparatus according to claim 1, wherein the potential difference is substantially zero when all the speakers are operating normally. Equipment inspection equipment. 3. The inspection apparatus for an electroacoustic apparatus according to claim 2, wherein the potential difference detecting means is configured such that the detection signal becomes substantially zero when the absolute value of the potential difference is equal to or less than a predetermined value. An inspection apparatus for an electro-acoustic device, which is characterized in that 4. The electroacoustic apparatus according to claim 2, further comprising an output unit that outputs one or both of visible information and audible information according to the detection signal. Inspection equipment. 5. The electroacoustic apparatus inspection apparatus according to claim 4, wherein the output means is formed by one or both of a light emitting diode and a buzzer.