Acoustics-Characteristics and specifications for laboratory standard condenser microphones
Some standard content:
National Standard of the People's Republic of China ||tt| ... Its electroacoustic characteristics have excellent long-term stability, almost unchanged with environmental conditions, and its changing relationship is known. The laboratory standard microphone is a reference or working standard instrument for measuring sound pressure in air.
Note: () The laboratory standard microphone is a capacitor sensor with a high internal resistance power supply to provide polarization voltage. ② The size, tolerance and electroacoustic performance of the laboratory standard microphone have strict requirements, so only a few types of microphones can be used as standard microphones. 2.3 Open circuit voltage
The open circuit voltage of the microphone under the sound pressure of a given frequency is the terminal voltage when the microphone load impedance is the optical limit. The terminal voltage of the capacitor microphone is related to its electrical load: Therefore, the open circuit voltage refers to the microphone terminal voltage measured by the insertion voltage method when the microphone has no other electrical load except the specified ground shielding structure. 2.4 Microphone sound pressure sensitivity
For a sinusoidal sound wave of a given frequency and given environmental conditions, the ratio of the microphone open circuit voltage to the sound pressure uniformly acting on the microphone diaphragm, symbol: M, unit, volt per Pascal, V/Pa. Note: The sound pressure sensitivity is a complex number, and when the sum is not considered, it can be expressed by its modulus attenuation. 2.5 Microphone vocal sensitivity level
The sensitivity of the microphone is usually expressed as "level \, and its expression is! M+--201g [M,/ M. 1
Where: M is the microphone sound pressure sensitivity level dB: M, a microphone sound pressure sensitivity, V/Pa; M, a microphone sensitivity level reference value, which is 1V/Pa. 2.6 Microphone sound pressure sensitivity phase angle
The phase angle between the microphone open circuit voltage and the sound pressure acting on the diaphragm at a given rate. The unit is: degree, (\). 2.7 Microphone free field sensitivity
Approved by the State Administration of Technical Supervision on October 12, 1989 and implemented on April 1, 1990
GB 11670—89
For a given frequency and given environmental conditions, the ratio of the microphone open circuit voltage to the free field sound pressure existing at the microphone acoustic center before the microphone is introduced into the sound field, symbol: f,. Unit: volt per Pascal, V/P. Note that the open circuit sensitivity value is a complex number and can be expressed by its modulus when the phase is ignored. 2.8 Microphone Free Field Sensitivity Level
Free field sensitivity is usually expressed as "level", and its expression is M,201glM:/M,
Where, M--transmitter free field sensitivity level, dB, Wr--microphone free field sensitivity, V/Pa; t--microphone sensitivity level basic value, 1V/Pa. 2.9 Microphone Free Field Sensitivity Phase Angle
At a given frequency, the phase angle between the microphone open circuit voltage and the voltage existing at the microphone acoustic center before the microphone is introduced into the sound field. Units: degrees, \,
2.10 Microphone electrical impedance
The complex ratio of the voltage at the terminals of a linear microphone to the resulting current at a given frequency. Units: ohms, \, Note: Microphone resistance is a function of the diaphragm load and the ground shield structure. 2.11 Microphone acoustic impedance
The complex ratio of the sound pressure acting on the diaphragm to the diaphragm volume velocity when the microphone terminal load is infinite impedance at a given frequency. The unit is Pascal seconds per cubic meter, Pa·s/m2.12 Transmitter Equivalent Volume
When the microphone is calibrated in the cavity, the equivalent volume is often used to express the acoustic impedance of the microphone. The specific expression is: "jcoZ
Microphone Equivalent Volume, and:
In: -
?——Specific heat ratio of gas under standard environmental conditions; P Static pressure under standard environmental conditions, Pa;
——Angular velocity, s\,
|Z. ——Acoustic impedance of microphone, Ps/m\. Note: Equivalent volume is a complex number and is a function of frequency. 2.13 Static pressure coefficient of microphone sensitivity level The static pressure coefficient of microphone at a given frequency. The ratio of the increase in static pressure caused by the change in the sensitivity level of microphone to the static pressure increment. The unit is: decibel per Pascal dB/Pa.
: The static pressure coefficient is generally the ratio of the frequency and static pressure. 2.14 Temperature coefficient of microphone sensitivity level The temperature coefficient of microphone at a given frequency The humidity coefficient is the ratio of the increase in the microphone sensitivity level with temperature changes to the temperature increase. The unit is: decibel per Kelvin/K.
Note: The temperature coefficient is generally a function of frequency and temperature. 2.15 Humidity coefficient of microphone sensitivity level The humidity coefficient of the microphone at a given frequency is the ratio of the increase in the microphone sensitivity level with humidity changes to the humidity increase. The unit is: decibel per percent relative humidity, dE/RH. 2.16 Stability coefficient of microphone sensitivity level The rate of change of the microphone sensitivity level within a specified time under normal environmental conditions. Stability is represented by the following two quantities. Long-term stability coefficient (systematic drift of microphone sensitivity) is expressed as the slope of the regression line. m is a graph with the measured sensitivity level as the ordinate and the corresponding time as the abscissa: the slope of the regression line obtained by linear regression. The measurement time of the long-term stability coefficient should not be less than one year, and the unit is: decibel per year, dB/a.
GB 11670-89
Short-term stability (reversible change of sensitivity of acoustic wave), expressed as standard deviation &, is expressed as: (ar )
Where: S-standard deviation, dB;
Number of measurements:
, — the sensitivity level of the first measurement, d
— the sensitivity level d at t-t obtained by the same equation mt+. In the reversible equation: the value of a return path in 10 inches is called:
— time.
The measurement base time of the short-term stability coefficient is 5 days, and 3 groups of measurements are carried out within 5 days. Each group should complete at least 3 measurements within 24 hours, and the time interval between two measurements should not be less than The measurement interval of each group should be no less than 2 hours. The measurement interval of each group should be no less than 124 hours. The third group of measurements should be completed within 3 days. Unit: decibel dB.
2.17 Normal laboratory environmental conditions
Temperature: 15～25℃
Static pressure, 90110kPa
Relative humidity: 25%~80%.
2.18 Standard laboratory environmental conditions
Temperature: 23℃;
Static pressure: 101.325kPa;
Relative humidity: 50%.
3 Characteristics of laboratory standard microphones
3.1 Sensitivity
The sound pressure at a certain point in the sound field is a scalar. Ideally, the measurement should be based on an infinitely small microphone. In fact, microphones always have a certain size. At high frequencies, a reflection effect will occur, which makes the microphone sensitivity related to the microphone installation method and the nature of the field. Due to the diffraction effect, different microphone sensitivities under various ideal sound fields are defined, namely, sound pressure sensitivity, white field sensitivity, etc. Usually, corresponding to the above-mentioned sensitivity, a microphone can be designed to make its sensitivity independent of frequency in the widest possible frequency range. Laboratory standard microphones are usually equipped with a protective cover to prevent accidental damage to the diaphragm. When calibrating to accurately measure the sound pressure level, the protective grille cover should be removed.
3.2 Impedance
The microphone acoustic impedance must be considered when measuring sound pressure in a standing wave tube and a small closed cavity. When the microphone is reciprocally calibrated in a cavity, the microphone acoustic impedance is the main part of the total acoustic transfer impedance. The acoustic impedance should be given as a function of frequency. Note: ① The microphone acoustic impedance can be expressed by the lumped parameters of an equivalent single-wavelength system, which has the same common frequency and low-frequency impedance. The lumped parameters can be acoustic compliance, acoustic mass and acoustic resistance, or resonant frequency, loss factor and equivalent volume at low frequency. 2. The sound pressure type microphone card should be used in a closed cavity, so the equivalent volume is particularly important for it. 3.3 Static pressure balance
The microphone back cavity is usually equipped with a pressure equalizing tube to form a pressure equalizing channel to make the static pressure on both sides of the diaphragm the same. Because the free field wave can pass into the microphone back cavity, the microphone free field sensitivity is significantly lower than the sound pressure sensitivity when the frequency is very low. The static pressure equalization capability is expressed by the time constant of the system composed of the microphone's pressure equalizing tube and the back cavity, and can also be expressed by the lower limit frequency 3dB lower than the field sensitivity level.
3. 4 Relationship between microphone sensitivity and static pressure
GE1167089
The static pressure of the air in the back cavity of the microphone will slightly affect the microphone sensitivity. The static pressure coefficient should be given as a function of frequency, and its applicable range is 90~110 kPa.
3.5 Relationship between microphone sensitivity and temperature
Changes in ambient temperature will affect the microphone sensitivity. The sensitivity change caused by slow changes in temperature within a certain range is reversible. Temperature shock may cause permanent changes in microphone sensitivity. The temperature coefficient should be given as a function of frequency, and its applicable range is 15-~25℃. 3. 6 Relationship between microphone sensitivity and hysteresis Hysteresis has little effect on microphone sensitivity. The applicable range of humidity coefficient is: 25%~-80% 3.7 Microphone capacitance
Microphone is also the most important component in the equivalent circuit of the receiver. The capacitor is related to the polarization voltage and the diaphragm acoustic load. It should be measured when the microphone is grounded and shielded as specified. In the low-frequency range of microphone stiffness control, when the diaphragm acoustic load is zero and the polarization voltage is the specified value, the capacitance is constant. 3.8 Insulation resistance
The insulation resistance value of the microphone should be measured after being placed in an environment with a temperature of 23℃, a relative humidity of 65℃ and a static pressure of 90-110kPa for 24 hours.
3. 9 Dynamic range of microphone
To meet the calibration needs, the microphone should have a sufficiently large dynamic range. The upper limit of the dynamic range is limited by the distortion of the microphone, and the lower limit is limited by the inherent noise of the microphone:
The upper limit of the dynamic range is expressed by the sound pressure level when the total harmonic distortion produced by the microphone in the low-frequency range of the stiffness control is 1%.
The lower limit of the dynamic range is expressed by the equivalent sound pressure level of the inherent noise of the microphone, which is related to the selected frequency band. The frequency band is usually specified as 22.4 Hz-~22.4 kHz.
3.10 Stability of microphone sensitivity
Even if the microphone is stored in a normal experimental environment, its sensitivity will change over time. The microphone stability coefficient should be measured at a polarization voltage of 200.0V and a frequency in the range of 200Hz to 1kHz (preferably 500Hz!). The measured sensitivity level should be corrected to the value under standard environmental conditions. 4 Specifications for laboratory standard microphones
4.1 Models
The models of laboratory standard microphones are specified as follows: The first two letters CB represent standard microphones, the following numbers (1 or 2) represent the nominal size category of the microphone, and then the letters (a or b) are the series numbers (24, 12 for series a; 23.77, 12 for series b). .7), the last letter (P or F) indicates the electroacoustic characteristics. P is the sound pressure type and F is the sound field type. This standard stipulates that the test standard microphone adopts the sound positive type microphone, so only the electroacoustic specifications of the sound pressure type are given in Table 3. However, its sensitivity and frequency response can also be used in free field and diffuse field after correction.
4.2 Mechanical structure and dimensions
The mechanical structure and dimensions and tolerances of the phase bottom of the sensor are shown in Figure 1 and Table 1 respectively. Model
Nominal diameter
Pitch c
Pitch D
4.3 Front peak
1. 95 ± 0. 04
GB11670-89
18.80±0.03
1. 95±0. 1
(60UNS)
6UUNS2B
Pitch C
General plate
Absolute body
9. 30 ± 0. 02
0. 50 -± 0. 05
0. 30±C. 93
0. 50 5
(60UNS-2B)
The laboratory standard microphone must meet the requirements of the fusion cavity reciprocity calibration. When calibrating at high frequencies, it is necessary to fill the coupling cavity with hydrogen or nitrogen. To prevent the gas in the coupling cavity from entering the microphone rear cavity, the opening of the static pressure equalization hole should be located behind the microphone. 4.4 Grounding shielding standard structure
GB 11670 89
The grounding shielding structure connected to the microphone is shown in Figure 2. The corresponding dimensions and tolerances are shown in Table 2. es
Internal shielding
Microphone
Insulation
External shielding-
Nominal diameter
4.5 Electrical specifications
9. 0+ Non-, 1
11. 0) - 0. 1
5. 01 (1. 1
9. 0±0. 1
11. 01. 0. 1
(60UNS-2B)
6. Non-+0. 07
6. 50 +:0. 05
5,0010. 15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone using an applied polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic characteristics listed in Table 3 are the values when the polarization voltage is 200.0V. The manufacturer shall summarize the typical data of each performance of the product according to the items listed in Table 3, and for items 1, 2, and 3 in Table 3, the measured data shall be given separately for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. The sensitivity of the microphone decreases at higher frequencies, so high-precision calibration cannot be performed above 8kHz. Under free field or diffuse field conditions, there is obvious directivity at high frequencies, and high-precision measurements cannot be made either.
Cn2P type microphones are used up to 20 kHz, but their sensitivity is lower. Item sound
Spirit number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure balance time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability
Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
Within the frequency range of item 2
Within the frequency range of item 2
155'℃
250hz---1 khz
Note: 1) Refers to the highest and lowest sensitivity difference within the specified frequency range. 0. 02 ~- 0. 02
0. 02 ~-+ 0. 02
10~-20000
0. 025~- : 0. 025
-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is issued by the National Technical Committee for Acoustic Standardization and drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:5 Microphone sensitivity and temperature coefficient
Changes in ambient temperature will affect microphone sensitivity. The sensitivity change caused by slow changes in humidity within a certain range is reversible. Surface humidity shock may cause permanent changes in microphone sensitivity. The temperature coefficient should be given as a function of frequency. Its applicable range is 15-~25℃. 3.6 Relationship between microphone sensitivity and humidity. Humidity has little effect on microphone sensitivity. The applicable range of humidity coefficient is: 25%~-80%. 3.7 Microphone capacitor
The microphone is also the most important component in the equivalent circuit of the receiver. The capacitor is related to the polarization voltage and the diaphragm acoustic load. It should be measured when the microphone is grounded and shielded according to the specified structure. In the low frequency range of the microphone stiffness control, when the diaphragm acoustic load is zero, the polarization voltage is 4.0°C, the electric quantity is constant, and the insulation resistance value of the microphone should be measured after being placed in an environment with a temperature of 23°C, a relative humidity of 65°C, and a static pressure of 90-110 kPa for 24 hours.
3. 9 Dynamic range of microphone
To meet the calibration requirements, the microphone should have a sufficiently large dynamic range. The upper limit of the dynamic range is limited by the distortion of the microphone, and the lower limit is limited by the inherent noise of the microphone:
The upper limit of the dynamic range is expressed by the sound pressure level when the total harmonic distortion generated by the microphone in the low frequency range of the stiffness control is 1%.
The lower limit of the dynamic range is expressed by the equivalent sound pressure level of the inherent noise of the microphone, which is related to the selected frequency band. The frequency band is usually specified as 22.4 Hz-~22.4 kHz.
3.10 Stability of Microphone Sensitivity
Even if the microphone is stored in a normal laboratory environment, its sensitivity will change over time. The microphone stability coefficient should be measured at a polarization voltage of 200.0V and a frequency in the range of 200Hz to 1kHz (preferably 500Hz!). The measured sensitivity level should be corrected to the value under standard environmental conditions. 4 Specifications for Laboratory Standard Microphones
4.1 Models
The model of laboratory standard microphones is specified as follows: The first two letters CB represent standard microphones, the following numbers (1 or 2) represent the nominal size category of the sensor, and then the letter (a or b) is the series number (24, 12 for series a; 23.77, 12 for series b). .7), the last letter (P or F) indicates the electroacoustic characteristics. P is the sound pressure type and F is the sound field type. This standard stipulates that the test standard microphone adopts the sound positive type microphone, so only the electroacoustic specifications of the sound pressure type are given in Table 3. However, its sensitivity and frequency response can also be used in free field and diffuse field after correction.
4.2 Mechanical structure and dimensions
The mechanical structure and dimensions and tolerances of the phase bottom of the sensor are shown in Figure 1 and Table 1 respectively. Model
Nominal diameter
Pitch c
Pitch D
4.3 Front peak
1. 95 ± 0. 04
GB11670-89
18.80±0.03
1. 95±0. 1
(60UNS)
6UUNS2B
Pitch C
General plate
Absolute body
9. 30 ± 0. 02
0. 50 -± 0. 05
0. 30±C. 93
0. 50 5
(60UNS-2B)
The laboratory standard microphone must meet the requirements of the fusion cavity reciprocity calibration. When calibrating at high frequencies, it is necessary to fill the coupling cavity with hydrogen or nitrogen. To prevent the gas in the coupling cavity from entering the microphone rear cavity, the opening of the static pressure equalization hole should be located behind the microphone. 4.4 Grounding shielding standard structure
GB 11670 89
The grounding shielding structure connected to the microphone is shown in Figure 2. The corresponding dimensions and tolerances are shown in Table 2. es
Internal shielding
Microphone
Insulation
External shielding-
Nominal diameter
4.5 Electrical specifications
9. 0+ Non-, 1
11. 0) - 0. 1
5. 01 (1. 1
9. 0±0. 1
11. 01. 0. 1
(60UNS-2B)
6. Non-+0. 07
6. 50 +:0. 05
5,0010. 15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone using an applied polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic characteristics listed in Table 3 are the values when the polarization voltage is 200.0V. The manufacturer shall summarize the typical data of each performance of the product according to the items listed in Table 3, and for items 1, 2, and 3 in Table 3, the measured data shall be given separately for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. The sensitivity of the microphone decreases at higher frequencies, so high-precision calibration cannot be performed above 8kHz. Under free field or diffuse field conditions, there is obvious directivity at high frequencies, and high-precision measurements cannot be made either.
Cn2P type microphones are used up to 20 kHz, but their sensitivity is lower. Item sound
Spirit number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure balance time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability
Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
Within the frequency range of item 2
Within the frequency range of item 2
155'℃
250hz---1 khz
Note: 1) Refers to the highest and lowest sensitivity difference within the specified frequency range. 0. 02 ~- 0. 02
0. 02 ~-+ 0. 02
10~-20000
0. 025~- : 0. 025
-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is issued by the National Technical Committee for Acoustic Standardization and drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:5 Microphone sensitivity and temperature coefficient
Changes in ambient temperature will affect microphone sensitivity. The sensitivity change caused by slow changes in humidity within a certain range is reversible. Surface humidity shock may cause permanent changes in microphone sensitivity. The temperature coefficient should be given as a function of frequency. Its applicable range is 15-~25℃. 3.6 Relationship between microphone sensitivity and humidity. Humidity has little effect on microphone sensitivity. The applicable range of humidity coefficient is: 25%~-80%. 3.7 Microphone capacitor
The microphone is also the most important component in the equivalent circuit of the receiver. The capacitor is related to the polarization voltage and the diaphragm acoustic load. It should be measured when the microphone is grounded and shielded according to the specified structure. In the low frequency range of the microphone stiffness control, when the diaphragm acoustic load is zero, the polarization voltage is 4.0°C, the electric quantity is constant, and the insulation resistance value of the microphone should be measured after being placed in an environment with a temperature of 23°C, a relative humidity of 65°C, and a static pressure of 90-110 kPa for 24 hours.
3. 9 Dynamic range of microphone
To meet the calibration requirements, the microphone should have a sufficiently large dynamic range. The upper limit of the dynamic range is limited by the distortion of the microphone, and the lower limit is limited by the inherent noise of the microphone:
The upper limit of the dynamic range is expressed by the sound pressure level when the total harmonic distortion generated by the microphone in the low frequency range of the stiffness control is 1%.
The lower limit of the dynamic range is expressed by the equivalent sound pressure level of the inherent noise of the microphone, which is related to the selected frequency band. The frequency band is usually specified as 22.4 Hz-~22.4 kHz.
3.10 Stability of Microphone Sensitivity
Even if the microphone is stored in a normal laboratory environment, its sensitivity will change over time. The microphone stability coefficient should be measured at a polarization voltage of 200.0V and a frequency in the range of 200Hz to 1kHz (preferably 500Hz!). The measured sensitivity level should be corrected to the value under standard environmental conditions. 4 Specifications for Laboratory Standard Microphones
4.1 Models
The model of laboratory standard microphones is specified as follows: The first two letters CB represent standard microphones, the following numbers (1 or 2) represent the nominal size category of the sensor, and then the letter (a or b) is the series number (24, 12 for series a; 23.77, 12 for series b). .7), the last letter (P or F) indicates the electroacoustic characteristics. P is the sound pressure type and F is the sound field type. This standard stipulates that the test standard microphone adopts the sound positive type microphone, so only the electroacoustic specifications of the sound pressure type are given in Table 3. However, its sensitivity and frequency response can also be used in free field and diffuse field after correction.
4.2 Mechanical structure and dimensions
The mechanical structure and dimensions and tolerances of the phase bottom of the sensor are shown in Figure 1 and Table 1 respectively. Model
Nominal diameter
Pitch c
Pitch D
4.3 Front peak
1. 95 ± 0. 04
GB11670-89
18.80±0.03
1. 95±0. 1
(60UNS)
6UUNS2B
Pitch C
General plate
Absolute body
9. 30 ± 0. 02
0. 50 -± 0. 05
0. 30±C. 93
0. 50 5
(60UNS-2B)
The laboratory standard microphone must meet the requirements of the fusion cavity reciprocity calibration. When calibrating at high frequencies, it is necessary to fill the coupling cavity with hydrogen or nitrogen. To prevent the gas in the coupling cavity from entering the microphone rear cavity, the opening of the static pressure equalization hole should be located behind the microphone. 4.4 Grounding shielding standard structure
GB 11670 89
The grounding shielding structure connected to the microphone is shown in Figure 2. The corresponding dimensions and tolerances are shown in Table 2. es
Internal shielding
Microphone
Insulation
External shielding-
Nominal diameter
4.5 Electrical specifications
9. 0+ Non-, 1
11. 0) - 0. 1
5. 01 (1. 1
9. 0±0. 1
11. 01. 0. 1
(60UNS-2B)
6. Non-+0. 07
6. 50 +:0. 05
5,0010. 15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone using an applied polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic characteristics listed in Table 3 are the values when the polarization voltage is 200.0V. The manufacturer shall summarize the typical data of each performance of the product according to the items listed in Table 3, and for items 1, 2, and 3 in Table 3, the measured data shall be given separately for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. The sensitivity of the microphone decreases at higher frequencies, so high-precision calibration cannot be performed above 8kHz. Under free field or diffuse field conditions, there is obvious directivity at high frequencies, and high-precision measurements cannot be made either.
Cn2P type microphones are used up to 20 kHz, but their sensitivity is relatively low. Item sound
Spirit number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure balance time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability
Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
Within the frequency range of item 2
Within the frequency range of item 2
155'℃
250hz---1 khz
Note: 1) Refers to the highest and lowest sensitivity difference within the specified frequency range. 0. 02 ~- 0. 02
0. 02 ~-+ 0. 02
10~-20000
0. 025~- : 0. 025
-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is issued by the National Technical Committee for Acoustic Standardization and drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:10 Stability of Microphone Sensitivity
Even if the microphone is stored in a normal laboratory environment, its sensitivity will change over time. The microphone stability coefficient should be measured at a polarization voltage of 200.0V and a frequency in the range of 200Hz to 1kHz (preferably 500Hz!). The measured sensitivity level should be corrected to the value under standard environmental conditions. 4 Specifications for Laboratory Standard Microphones
4.1 Model
The model of laboratory standard microphones is specified as follows: The first two letters CB represent standard microphones, the following numbers (1 or 2) represent the nominal size category of the sensor, and then the letter (a or b) is the series number (24, 12 for series a; 23.77, 12 for series b). .7), the last letter (P or F) indicates the electroacoustic characteristics. P is the sound pressure type and F is the sound field type. This standard stipulates that the test standard microphone adopts the sound positive type microphone, so only the electroacoustic specifications of the sound pressure type are given in Table 3. However, its sensitivity and frequency response can also be used in free field and diffuse field after correction.
4.2 Mechanical structure and dimensions
The mechanical structure and dimensions and tolerances of the phase bottom of the sensor are shown in Figure 1 and Table 1 respectively. Model
Nominal diameter
Pitch c
Pitch D
4.3 Front peak
1. 95 ± 0. 04
GB11670-89
18.80±0.03
1. 95±0. 1
(60UNS)
6UUNS2B
Pitch C
General plate
Absolute body
9. 30 ± 0. 02
0. 50 -± 0. 05
0. 30±C. 93
0. 50 5
(60UNS-2B)
The laboratory standard microphone must meet the requirements of the fusion cavity reciprocity calibration. When calibrating at high frequencies, it is necessary to fill the coupling cavity with hydrogen or nitrogen. To prevent the gas in the coupling cavity from entering the microphone rear cavity, the opening of the static pressure equalization hole should be located behind the microphone. 4.4 Grounding shielding standard structure
GB 11670 89
The grounding shielding structure connected to the microphone is shown in Figure 2. The corresponding dimensions and tolerances are shown in Table 2. es
Internal shielding
Microphone
Insulation
External shielding-
Nominal diameter
4.5 Electrical specifications
9. 0+ Non-, 1
11. 0) - 0. 1
5. 01 (1. 1
9. 0±0. 1
11. 01. 0. 1
(60UNS-2B)
6. Non-+0. 07
6. 50 +:0. 05
5,0010. 15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone using an applied polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic characteristics listed in Table 3 are the values when the polarization voltage is 200.0V. The manufacturer shall summarize the typical data of each performance of the product according to the items listed in Table 3, and for items 1, 2, and 3 in Table 3, the measured data shall be given separately for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. The sensitivity of the microphone decreases at higher frequencies, so high-precision calibration cannot be performed above 8kHz. Under free field or diffuse field conditions, there is obvious directivity at high frequencies, and high-precision measurements cannot be made either.
Cn2P type microphones are used up to 20 kHz, but their sensitivity is lower. Item sound
Spirit number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure balance time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability
Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
Within the frequency range of item 2
Within the frequency range of item 2
155'℃
250hz---1 khz
Note: 1) Refers to the highest and lowest sensitivity difference within the specified frequency range. 0. 02 ~- 0. 02
0. 02 ~-+ 0. 02
10~-20000
0. 025~- : 0. 025
-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is issued by the National Technical Committee for Acoustic Standardization and drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:10 Stability of Microphone Sensitivity
Even if the microphone is stored in a normal laboratory environment, its sensitivity will change over time. The microphone stability coefficient should be measured at a polarization voltage of 200.0V and a frequency in the range of 200Hz to 1kHz (preferably 500Hz!). The measured sensitivity level should be corrected to the value under standard environmental conditions. 4 Specifications for Laboratory Standard Microphones
4.1 Model
The model of laboratory standard microphones is specified as follows: The first two letters CB represent standard microphones, the following numbers (1 or 2) represent the nominal size category of the sensor, and then the letter (a or b) is the series number (24, 12 for series a; 23.77, 12 for series b). .7), the last letter (P or F) indicates the electroacoustic characteristics. P is the sound pressure type and F is the sound field type. This standard stipulates that the test standard microphone adopts the sound positive type microphone, so only the electroacoustic specifications of the sound pressure type are given in Table 3. However, its sensitivity and frequency response can also be used in free field and diffuse field after correction.
4.2 Mechanical structure and dimensions
The mechanical structure and dimensions and tolerances of the phase bottom of the sensor are shown in Figure 1 and Table 1 respectively. Model
Nominal diameter
Pitch c
Pitch D
4.3 Front peak
1. 95 ± 0. 04
GB11670-89
18.80±0.03
1. 95±0. 1
(60UNS)
6UUNS2B
Pitch C
General plate
Absolute body
9. 30 ± 0. 02
0. 50 -± 0. 05
0. 30±C. 93
0. 50 5
(60UNS-2B)
The laboratory standard microphone must meet the requirements of the fusion cavity reciprocity calibration. When calibrating at high frequencies, it is necessary to fill the coupling cavity with hydrogen or nitrogen. To prevent the gas in the coupling cavity from entering the microphone rear cavity, the opening of the static pressure equalization hole should be located behind the microphone. 4.4 Grounding shielding standard structure
GB 11670 89
The grounding shielding structure connected to the microphone is shown in Figure 2. The corresponding dimensions and tolerances are shown in Table 2. es
Internal shielding
Microphone
Insulation
External shielding-
Nominal diameter
4.5 Electrical specifications
9. 0+ Non-, 1
11. 0) - 0. 1
5. 01 (1. 1
9. 0±0. 1
11. 01. 0. 1
(60UNS-2B)
6. Non-+0. 07
6. 50 +:0. 05
5,0010. 15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone using an applied polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic characteristics listed in Table 3 are the values when the polarization voltage is 200.0V. The manufacturer shall summarize the typical data of each performance of the product according to the items listed in Table 3, and for items 1, 2, and 3 in Table 3, the measured data shall be given separately for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. The sensitivity of the microphone decreases at higher frequencies, so high-precision calibration cannot be performed above 8kHz. Under free field or diffuse field conditions, there is obvious directivity at high frequencies, and high-precision measurements cannot be made either.
Cn2P type microphones are used up to 20 kHz, but their sensitivity is lower. Item sound
Spirit number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure balance time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability
Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
Within the frequency range of item 2
Within the frequency range of item 2
155'℃
250hz---1 khz
Note: 1) Refers to the highest and lowest sensitivity difference within the specified frequency range. 0. 02 ~- 0. 02
0. 02 ~-+ 0. 02
10~-20000
0. 025~- : 0. 025
-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is issued by the National Technical Committee for Acoustic Standardization and drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone with an external polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic properties listed in Table 3 are values when the polarization voltage is 200.0V. Manufacturers should provide typical data of each performance of products according to the items listed in Table 3. , 2, 3, the measured data should be given for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. Microphone sensitivity decreases at higher frequencies, so high accuracy calibration cannot be performed above 8kHz. In free field or diffuse field conditions, high-precision measurements cannot be made due to the obvious directivity at high frequencies. kHz. But its sensitivity is low. Item soundbzxZ.net
Spiritual number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure equalization time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability| |tt||Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
within the frequency range of item 2
tt||within item 2 frequency requirement
range
155'℃
250hz---1khz
Note: 1) refers to the highest and lowest sensitivity within the specified frequency range 0.02 ~- 0.02
0.02 ~-+ 0.02
10~-20000
0.025~- : 0.025||tt ||-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is recommended by the National Acoustic Standardization Technical Committee This standard was drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:15
6.50±0.07
7. (+ (1. 07
5. ±0. 15
(60UNS-28)
The electroacoustic specifications of the laboratory standard microphone are listed in Table 3. The laboratory standard microphone is a capacitor microphone with an external polarization voltage. The specified polarization voltage is 200.0V. All electroacoustic properties listed in Table 3 are values when the polarization voltage is 200.0V. Manufacturers should provide typical data of each performance of products according to the items listed in Table 3. , 2, 3, the measured data should be given for each microphone. CBIP type microphones are calibrated with high accuracy at medium and low frequencies. Microphone sensitivity decreases at higher frequencies, so high accuracy calibration cannot be performed above 8kHz. In free field or diffuse field conditions, high-precision measurements cannot be made due to the obvious directivity at high frequencies. kHz. But its sensitivity is low. Item sound
Spiritual number level
Frequency response
Equivalent volume
Resonance frequency
Upper limit of dynamic range
Insulation resistance
Static pressure equalization time band"
Static pressure coefficient
Temperature coefficient
Humidity coefficient
Long-term stability| |tt||Short-term stability
2~50Hz
Within 2
20()--5(0 Hz
1% distortion
200~5001
GB11670—89
--26 —2
10-8000
150±30
55—5
Within the frequency range of item 2
tt||In item 2 frequency requirement
range
155'℃
250hz---1khz
Note: 1) refers to the highest and lowest sensitivity within the specified frequency range 0. 02 ~- 0. 02
0. 02 ~-+ 0. 02
10~-20000
0. 025~- : 0. 025||tt ||-0, 02~. +n. (12
. (. 0 001
2) Unless there are special reasons, the time constant should not be greater than 1. Otherwise, it is difficult to meet the requirements of short-term stability. Additional remarks:
This standard is recommended by the National Acoustic Standardization Technical Committee This standard was drafted by the Institute of Acoustics, Chinese Academy of Sciences. Unit
dB(d1 V/Pa)
dB( (dB20μPa)
dB/kpa
dh/(ah:
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