JP2001349773A - Sound calibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sound calibrator for efficient sound calibration without minding a change in atmospheric pressure. SOLUTION: The sound calibrator having a pressure type microphone 9 inserted in a coupler 8 for generating a sound pressure in the coupler with an electromagnetic earphone 7 and supplying the sound pressure to the pressure type microphone 9 comprises an atmospheric pressure sensor 1 for detecting an atmospheric pressure and sound pressure control means 2, 3, 4, 5 for controlling the electromagnetic earphone 7 to give a preset sound pressure to the coupler 8 corresponding to a value detected by the atmospheric pressure sensor 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an acoustic calibrator for calibrating the sensitivity of an acoustic measuring instrument such as a sound level meter having a pressure type microphone.

[0002]

2. Description of the Related Art In order to maintain the accuracy of an acoustic measuring instrument such as a sound level meter equipped with a pressure type microphone, it is necessary to periodically perform an acoustic calibration of the pressure type microphone. For this purpose, an acoustic calibrator is used. .

A conventional sound calibrator is, as shown in FIG.
Coupler 1 for inserting microphone 100 to be calibrated
01, an electro-acoustic transducer 102 for supplying a calibration sound of a predetermined sound pressure to the coupler 101, an amplifier 103 for driving the electro-acoustic transducer 102, and a stable and constant sound pressure signal input to the electro-acoustic transducer 102 through the amplifier 103. Signal source 104
It is composed of In addition, a barometer and a table for barometric pressure correction are attached.

A barometer and a table for barometric pressure correction are stored in a signal source 104.
Is constant, the sound pressure output from the electroacoustic transducer 102 changes when the atmospheric pressure changes. Therefore, when the calibration operator corrects the calibration sound, it is necessary for the sound calibrator. I was

[0005]

However, in the acoustic calibrator shown in FIG. 3, the measuring operator must pay attention to the change in the atmospheric pressure, and must correct the atmospheric pressure when the atmospheric pressure changes. The work was complicated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide an acoustic calibration device capable of efficiently performing acoustic calibration without worrying about changes in atmospheric pressure. It is intended to provide a calibrator.

[0007]

According to the present invention, a pressure-type microphone is inserted into a coupler, and a sound pressure is generated in the coupler by electro-acoustic conversion means. In an acoustic calibrator for supplying to a microphone, an atmospheric pressure detecting means for detecting an atmospheric pressure and the electroacoustic converting means for controlling the inside of the coupler to a predetermined sound pressure corresponding to a detected value of the atmospheric pressure detecting means. Sound pressure control means.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a configuration diagram of an acoustic calibrator according to the present invention, and FIG. 2 shows three types of calibration sound signal waveforms (minimum amplitude,
FIG.

Generally, when an electroacoustic transducer such as an electromagnetic earphone is driven by a fixed input to generate a sound pressure in a cavity of a coupler, when the atmospheric pressure changes, the sound pressure generated in the cavity also increases. It changes according to the value of the atmospheric pressure (the sound pressure increases as the atmospheric pressure increases, and the sound pressure decreases as the atmospheric pressure decreases).

Therefore, a general electroacoustic transducer cannot cope with a change in the atmospheric pressure and cannot supply a constant sound pressure. Therefore, unless a corrective operation using a barometer and a table for the atmospheric pressure correction is performed, accurate electroacoustic transducers are required. Acoustic calibration cannot be performed.

Therefore, an acoustic calibrator according to the present invention is shown in FIG.
As shown in FIG. 1, an atmospheric pressure sensor 1, an A / D converter 2,
It comprises an arithmetic and control unit 3, a storage unit 4, a D / A converter 5, an amplifier 6, an electromagnetic earphone 7, and a coupler 8. Reference numeral 9 denotes a pressure type microphone to be calibrated.

The atmospheric pressure sensor 1 detects an atmospheric pressure and outputs an electric signal corresponding to the atmospheric pressure. The A / D converter 2 converts an analog signal output from the atmospheric pressure sensor 1 into a digital signal, and outputs the digital signal to the arithmetic and control unit 3.

The arithmetic and control unit 3 calculates the atmospheric pressure from the output signal of the A / D converter 2 and obtains an optimum amplitude as a calibration sound signal waveform corresponding to the calculated atmospheric pressure. A calibration sound signal waveform having a similar amplitude is selected from those stored in the storage unit 4 in advance, and is output to the D / A converter 5.

[0014] The storage unit 4 for outputting always a constant calibration sound pressure despite variations in the atmospheric pressure from the electromagnetic type earphone 7, etc. is the amplitude of the calibration sound signal waveform from the minimum value a ₁ to a maximum value a _n Set at intervals (a ₁ , a ₂ , a ₃ ,..., A _n ),
These amplitude values _{(a 1, a 2, a} 3, ......, a n) calibration sound signal waveform having a _{(Y 1, Y 2, Y} 3, ......, Y n) are stored. That is, the amplitude value of the calibration sound signal waveform Y ₁ is a ₁ ,
Amplitude values of the calibration sound signal waveform Y ₂ is a _2, ......, the amplitude values of the calibration sound signal waveform Y _n is the a _n.

FIG. 2 shows the minimum amplitude value when 300 types (n = 300) of calibration sound signal waveforms (Y ₁ , Y ₂ , Y ₃ ,..., Y ₃₀₀ ) are stored in the storage unit 4. calibration sound signal waveform Y ₁ having a _1, a calibration sound signal waveform Y _0.99 with intermediate amplitude value a _0.99, shows a calibration sound signal waveform Y ₃₀₀ having a maximum amplitude value a _300.

The D / A converter 5 converts a digital signal from the arithmetic and control unit 3 into an analog signal, and converts it into an amplifier 6
Output to The amplifier 6 amplifies the analog signal output from the D / A converter 5 to a desired level and outputs the signal to the electromagnetic earphone 7. The electromagnetic earphone 7 is driven by the analog signal amplified by the amplifier 6, and outputs a calibration sound having a desired sound pressure to the cavity 8 a of the coupler 8.

The coupler 8 couples the electromagnetic earphone 7 and the pressure type microphone 9 to be calibrated via a small volume cavity 8a. The electromagnetic earphone 7 is fixed to the coupler 8,
The pressure type microphone 9 is detachably attached to the insertion port 8b of the coupler 8. Reference numeral 8c denotes a communication hole that communicates the outside air with the cavity 8a.

The operation of the thus constructed acoustic calibrator according to the present invention will be described. First, as shown in FIG. 1, the pressure type microphone 9 to be calibrated is mounted on the insertion port 8b of the coupler 8.

When a start switch (not shown) is turned on, the atmospheric pressure sensor 1 detects the atmospheric pressure and outputs an electric signal corresponding to the atmospheric pressure. Then, the A / D converter 2 converts the analog signal output from the atmospheric pressure sensor 1 into a digital signal, and outputs the digital signal to the arithmetic and control unit 3.

The arithmetic and control unit 3 calculates the atmospheric pressure from the output signal of the A / D converter 2, obtains an optimum amplitude corresponding to the calculated atmospheric pressure, and obtains a calibration sound having an amplitude closest to the amplitude. The signal waveform is selected from calibration sound signal waveforms (Y ₁ , Y ₂ , Y ₃ ,..., Y _n ) stored in the storage unit 4 in advance. The selected calibration sound signal waveform is input to the D / A converter 5.

The D / A converter 5 converts the digital signal from the operation / control section 3 into an analog signal and outputs it to the amplifier 6. The amplifier 6 amplifies the analog signal output from the D / A converter 5 to a desired level and outputs the amplified signal to the electromagnetic earphone 7.

Then, the electromagnetic earphone 7 is driven by the analog (current) signal amplified by the amplifier 6, and outputs a calibration sound having a desired sound pressure to the cavity 8 a of the coupler 8. Therefore, by controlling the input current to the electromagnetic earphone 7, a constant calibration sound pressure is always output from the electromagnetic earphone 7 regardless of the fluctuation of the atmospheric pressure.

In the above-described embodiment of the present invention, 300 types of calibration sound signal waveforms having the optimum amplitude waveform corresponding to the fluctuating atmospheric pressure value are stored in the storage unit 4 in advance and selected. However, instead of using the storage unit 4, the calculation and control unit 3 may calculate and generate and output a waveform having an optimum amplitude each time. Although the case where the electromagnetic earphone 7 is used as the electroacoustic conversion means has been described, an electroacoustic conversion means such as an electrodynamic type may be used.

[0024]

As described above, according to the present invention, even if the atmospheric pressure changes, the sound pressure of the electroacoustic conversion means is automatically adjusted so that the sound pressure of the calibration sound generated by the electroacoustic conversion means becomes constant. Since the input signal is controlled, the sound calibration of the sound level meter or the like can be efficiently performed without worrying about the atmospheric pressure fluctuation.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an acoustic calibrator according to the present invention.

FIG. 2 is a diagram showing three types (minimum amplitude, intermediate amplitude, and maximum amplitude) of a calibration sound signal waveform selected according to the magnitude of the amplitude as a representative example.

FIG. 3 is a configuration diagram of a conventional acoustic calibrator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Atmospheric pressure sensor, 2 ... A / D converter, 3 ... Calculation / control part, 4 ... Storage part, 5 ... D / A converter, 6 ... Amplifier, 7 ...
Electromagnetic type earphone, 8 ... coupler, 9 ... pressure type microphone.

Claims (1)

[Claims] A pressure type microphone is inserted into a coupler, a sound pressure is generated in the coupler by electro-acoustic conversion means, and an atmospheric pressure is detected by an acoustic calibrator for supplying the sound pressure to the pressure type microphone. Acoustic calibration comprising: an atmospheric pressure detecting means; and a sound pressure controlling means for controlling the electroacoustic converting means so that the inside of the coupler has a predetermined sound pressure according to a detection value of the atmospheric pressure detecting means. vessel.