RU139778U1 - DEVICE FOR ACOUSTIC ANTIBOISE TESTS - Google Patents

Abstract

1. A device for acoustic tests of anti-noise, the cylindrical body of which is made of non-magnetic metal, equipped with: a measuring microphone-condenser-type pressure receiver located in the plane of one of the bases of the cylinder so that the central axis of the microphone coincides with the center of its diaphragm and with the central axis of the cylinder; a support plate protruding from the center of the cylinder along its generatrix at right angles to the central axis, to the free end of which a rubber collar is connected; elastic mount to support the device in the acoustic field; a device, a soundproofing ring and marks on the end ends of the device for fixing anti-noise, providing hermetic closure of the device; a removable static pressure equalization tube, which fits snugly to the bottom of the cylinder after fixing the anti-noise, characterized in that it also includes a condenser-type control microphone-receiver for monitoring the immutability of the acoustic field parameters, and an external suspension, allowing, rotating the device around the axis, sequentially fix it in several positions, and the stand of the device is equipped with a screw mechanism that allows you to adjust its height. 2. The device according to claim 1, characterized by the inclusion of additional measuring and control microphones for acoustic testing simultaneously of two cups (caps) of noise-protective headphones. 3. The device according to claim 1, characterized in that the measuring and control microphones have a nominal diameter of 12 mm or 24 mm. The device according to claim 1, characterized in that

Description

The claimed technical solution relates to measuring equipment, and in particular to devices for measuring the acoustic effectiveness of anti-noise.

A special device for acoustic testing is known from the state of the art (See GOST Ρ 12.4.213-99 (ISO 4869-3-89) "Occupational Safety Standards System. Personal Protective Equipment for Hearing Organ. Antinoise. A Simplified Method for Measuring the Acoustic Efficiency of Antinoise Headphones for quality assessment. "- Introduced from 01.01.2002. - M.: IPK Standards Publishing House, 2000. - 11 s). The named device has the following design features.

1) The device is made of non-magnetic metal, for example, aluminum alloy or brass.

2) The body of the device has a cylindrical shape with a horizontal axis of 145 ± 1 mm between the centers of the end ends, the diameter of this cylinder is 135 ± 5 mm, and the angles of each of both ends are inclined, have an angle of inclination of 4.5 ° ± 0.5 ° with respect to to the vertical plane.

3) The measuring microphone has a nominal diameter of 24 mm and is a microphone - a condenser-type pressure receiver located so that its central axis coincides with the central axis of the cylinder and with the center of its diaphragm in the plane of one of the ends along the center line of the cylinder.

4) A support pad protruding from the center of the cylinder along a length at right angles to its central axis to support the headband of soundproofing headphones during the test. The length of the lining along the central axis of the cylinder is 123 ± 1 mm, and the radius of its free end is 100 ± 1 mm. A rubber collar with a thickness of 6 ± 1 mm, a width of the free end of 50 ± 1 mm and a length of 77 ± 1 mm is connected to this end of the cover for an elastic fit of soundproofing headphones on the headband.

5) A device for fixing anti-noise in the device, surrounded by a soundproofing ring.

6) In order to be able to equalize the static pressure under the noise during installation, the device is equipped with a removable tube, which is removed before the test and installed so as to deform the elastic collar, or with a fixed capillary tube with a diameter of 0.5 mm, 25 mm long, connected to the cavity under anti-noise and external air environment, with the possibility of parallel and close to the axis of the measuring microphone and devices for acoustic testing, providing overlapping wire di meter 0.4 mm and the compound with a tube diameter of approximately 3 mm, extending from the bottom of the cylinder is perpendicular to the microphone axis, and a fixed tube for pressure equalization should adjoin to a bottom of the cylinder after fixing the test insert hearing protector.

7) The acoustic insulation of the test device should be at least 50 dB for carrier frequencies from 63 to 250 Hz, at least 65 dB for carrier frequencies from 315 to 4000 Hz, and at least 55 dB for carrier frequencies of a higher range at the venue tests when measuring a test signal with a microphone covered by the studied anti-noise.

8) The test anti-noise must close the device hermetically, it is attached to the device when its central axis is rotated to a vertical position or with the help of a rubber band.

9) The device is supported in the acoustic field by means of an elastic mount so as to achieve a sufficiently low sound threshold.

10) The vertical and horizontal diameters of the device are marked at its end ends by applying along the two or three concentric circles of the appropriate radius in order to correctly orient the tested anti-noise.

However, the known device has the following disadvantages:

- there is no possibility to control the immutability of the acoustic field parameters during anti-noise tests;

- an elastic mount designed to maintain the device in the field of the generated sound field in the interest of minimizing threshold noise, does not allow the device to be moved inside the test chamber around its axis with sequential fixation in several positions necessary to ensure uniform arrival of acoustic waves from different directions.

- the stand of the device does not allow you to adjust its height, which complicates the correct orientation of the tested anti-noise relative to the axes of the device and its measuring microphone.

The technical task of the proposed utility model is to increase the efficiency of measuring the acoustic efficiency of anti-noise.

The solution to the technical problem is achieved by the fact that the device for acoustic tests of anti-noise, the cylindrical body of which is made of non-magnetic metal, is equipped with: a condenser-type measuring microphone-receiver located in the plane of one of the cylinder bases so that the central axis of the microphone coincides with the center of its diaphragm and with the central axis of the cylinder; a support plate protruding from the center of the cylinder along its generatrix at right angles to the central axis, to the free end of which a rubber collar is connected; elastic mount to support the device in the acoustic field; a device, a soundproofing ring and marks on the end ends of the device for fixing anti-noise, providing hermetic closure of the device; a removable static pressure equalization tube that fits snugly to the bottom of the cylinder after fixing the anti-noise, characterized in that it additionally includes a condenser-type control microphone-receiver for monitoring the immutability of the acoustic field parameters, and an external suspension allowing, rotating the device around the axis, sequentially fix it in several positions, and the stand of the device is equipped with a screw mechanism that allows you to adjust its height. The device may include additional measuring and control microphone for acoustic testing simultaneously of two cups (caps) of noise-protective headphones. The measuring and control microphone of the device, as a rule, have a nominal diameter of 12 mm or 24 mm. The device may further comprise an automatic control unit of the acoustic field parameters connected to the output of the control microphone and calculating the difference between the average values of sound pressure in each of the octave bands during the test of anti-noise with the same average values of sound pressure in the absence of an anti-noise, with the formation and generation of a signal about violation acoustic test conditions when the module exceeds the difference in the average values of sound pressure of 1 dB. It is advisable to place the control microphone of the device at a distance of 50 mm from the measuring microphone. It is advisable to equip the device with an external suspension connected to an elastic mount, allowing, rotating the device around an axis, to fix it in six positions in succession with a resolution of 60 °. The sound attenuation coefficient from the back of the measuring and control microphone should exceed 15 dB. It is advisable that the measuring and control microphones provide measurement of sound pressure levels in the frequency range from 2 to 16000 Hz. The dynamic range of the measurement and control microphones, as a rule, exceeds 80 dB. The unevenness of the amplitude-frequency characteristics of the measuring and control microphones of the device within the operating frequency range should be no more than ± 1 dB. The sensitivity of the measuring and control microphones of the device within the operating frequency range, as a rule, should be at least 50 mV / Pa. For visual inspection of compliance with the conditions of acoustic tests, the housing of the device can be made of polymethyl methacrylate, or polycarbonate, or polyvinyl chloride or polystyrene. The outputs of the measuring and control microphones can be equipped with additional connectors that allow you to connect an automatic clamp for recorded sound pressure levels with recording information in a drive with non-volatile memory.

The technical result provided by the given set of features is to increase the efficiency of measuring the acoustic efficiency of noise due to:

- ensuring the control of the invariance of the acoustic field parameters during anti-noise tests through the use of an additionally installed control microphone;

- the presence of an external suspension that allows you to move the device inside the test chamber around its axis with sequential fixation in several positions, to ensure that acoustic waves coming from different directions are taken into account in assessing the acoustic efficiency of the noise reduction.

- more accurate and conveniently implemented positioning of the device and the tested anti-noise in the acoustic field due to the implementation of the possibility of adjusting the height of the rack of the device using a screw mechanism.

The essence of the developed device for acoustic testing of noise is illustrated by figures 1 and 2:

figure 1. - Diagram of a device for acoustic testing of anti-noise, front view;

figure 2. - Schematic diagram of a device for acoustic noise control testing, side view

Both figures are adapted fragments of Figure 1 from GOST R 12.4.213-99 (ISO 4869-3-89) “Occupational safety standards system. Personal protective equipment for the hearing organ. Antinoise. A simplified method for measuring the acoustic performance of anti-noise headphones for quality assessment. ” - Entered into force on 01.01.2002. - M .: IPK Publishing House of Standards, 2000. - 11 p., With the following notation:

1 - Case.

2 - Support pad.

3 - Labels for installing an anti-noise device.

4 - Stand.

5 - External suspension.

6 - Measuring microphone.

7 - Removable tube for equalizing static pressure.

8 - Device for fixing anti-noise.

9 - Soundproof ring.

10 - Bead.

11 - Elastic fastening.

12 - Control microphone.

13 - Screw mechanism for adjusting the height of the rack.

A device for acoustic noise testing (see Figs. 1 and 2), the housing (1) of which, made of non-magnetic metal, has the shape of a cylinder and is equipped with: a measuring microphone (6) - a condenser type pressure receiver located in the plane of one of the cylinder bases so that the central axis of the microphone (6) coincides with the center of its diaphragm and with the central axis of the cylinder (1); a support pad (2) protruding from the center of the cylinder (1) along its generatrix at right angles to the central axis, to the free end of which a rubber collar (10) is connected; elastic mount (11) to maintain the device in the acoustic field; a device (8), a sound insulating ring (9) and marks (3) at the end ends of the device for fixing the noise, providing a hermetic closure of the device; with a removable tube (7) for equalizing the static pressure that fits snugly to the bottom of the cylinder after fixing the anti-noise, characterized in that it also includes a control microphone (12) - a condenser-type pressure receiver for monitoring the immutability of the acoustic field parameters, and an external suspension (5 ) connected to an elastic mount, allowing, rotating the device around an axis, to sequentially fix it in several positions, moreover, the stand (4) of the device is equipped with a screw mechanism (13) that allows adjusting vat her height.

For acoustic tests of two cups (caps) of noise-protective headphones at the same time, it is advisable to include additional measuring (6) and control (12) microphones in the device.

In the interest of providing acoustic testing of a wide class of noise suppressors, it is practical for the measurement (6) and control (12) microphones to have a nominal diameter of 12 mm or 24 mm.

For automated control of the constancy of the acoustic field, it is advisable to equip the device with an automatic control unit of the acoustic field parameters, connected to the output of the control microphone (12) and calculating the difference between the average values of sound pressure in each of the octave bands during the test of anti-noise with the same average values of sound pressure in the absence of an anti-noise , with the formation and issuance of a signal about violation of the conditions of acoustic tests when the module exceeds the difference and averaged sound pressure values of 1 dB.

The results of experimental studies show that it is advisable to place the control microphone (12) at a distance of 50 mm from the measuring microphone (6).

To standardize acoustic tests, it is advisable that the external suspension (5), allowing, rotating the device around the axis, sequentially fix it in six positions with a resolution of 60 °.

The sound attenuation coefficient from the back of the measuring (6) and control (12) microphones must not exceed 15 dB, their dynamic range must not be less than 80 dB, the sensitivity within the operating frequency range must be at least 50 mV / Pa, and the unevenness is amplitude - The frequency response within the operating frequency range should be no more than ± 1 dB.

For acoustic tests of anti-noise at all physiologically significant frequencies, it is necessary that the measuring (6) and control (12) microphones provide sound pressure levels in the frequency range from 2 to 16000 Hz.

For visual verification of compliance with acoustic test conditions, the housing (1) of the device can be made of polymethyl methacrylate, polycarbonate, polyvinyl chloride or polystyrene.

To automatically record the results of acoustic tests, the outputs of the measuring (1) and control (12) microphones can be equipped with additional connectors that allow you to connect an automatic clamp for recorded sound pressure levels with recording information in a non-volatile memory drive.

The operation of the device for acoustic tests of anti-noise is as follows.

Before starting acoustic tests, ensure that the background noise level at the acoustic test site, measured in the band of one third of an octave, is at least 10 dB less than the sound pressure level of the test signal (hereinafter the measuring microphone is placed strictly at measurements).

Then, without installing the tested anti-noise, the device is placed in an acoustic field, adjusting the height of the device using a screw mechanism located on its rack (without changing the height during the anti-noise testing time) and the average sound pressure values in each of the studied octave bands are recorded.

The test anti-noise is fixed in the fixture for fixation, which is part of the device, so as to ensure that the shock absorbers are located at each end of the anti-noise device. The anti-noise headband (if equipped) is placed symmetrically and so that it only touches the support pad. For anti-noise with a mount under the chin, the head belt (if provided) passes through the upper part of the support pad of the device. The neck dressings (if any) of the anti-noise device are positioned so that their ear caps are, if possible, parallel to the end ends of the device.

After installing the anti-noise in the device, using removable tubes, if necessary, equalize the static pressure under the anti-noise, and its position, taken as a reference, is rigidly fixed, tied to the location of the marks applied to the device.

When testing an antinoise having a headband, after it is fixed in the device for 30 s, the pressing force between the cups is measured, deflecting the opposite edges of the anti-noise shock absorbers 145 mm from each other and measuring the distance between the centers of the headband (on the inner surface) and between the centers of its cups ( the headband must be loose during measurement).

The device for conducting acoustic tests is oriented so that the acoustic field is tangential to the end end of the device. After this, the conditions are achieved under which the fixation of the tested anti-noise would lead to a decrease in the output signal at the measuring microphone by at least 10 dB.

Further, an acoustic signal is supplied to the device location using acoustic testing equipment, ensuring that the acoustic field of the test is formed by randomly incident fields or by a plane traveling wave. At each studied octave frequency in each fixed (using an external suspension) position of the device, at least twice the sound pressure level is measured for 30 s. For each frequency of the test acoustic signal, the difference between the measured sound pressure levels is the acoustic efficiency of the test noise at the corresponding octave frequency.

Wherein:

the constancy of the acoustic field is controlled by calculating the difference between the average values of sound pressure in each of the octave bands during the test of anti-noise with the same average values of sound pressure in the absence of anti-noise in the device (if the module exceeds the difference of the average values of sound pressure of 1 dB, the acoustic field is considered unstable, and the test conditions unfulfilled);

provide changes in the sound pressure level of the test acoustic signal by no more than ± 1 dB compared with the level established before the measurement;

provide the amplitude-frequency characteristic of the test acoustic signal with a bandwidth of one-third octave of penetrating noise in the framework of the test so that the difference between two adjacent ranges is not more than 5 dB, and when measured with pure tones during the test, it should change by no more than 10 dB within any band one-third of an octave wide.

Acoustic tests should be repeated a sufficient number of times (but not less than three times), until the difference between two successive average values of sound absorption by noise at each octave frequency does not exceed 1 dB.

After that, an acoustic test report is generated.

Thus, the described elements of the inventive device for acoustic testing of anti-noise are functionally interconnected and are in constructive unity, and the combination of its essential features is unknown from the prior art. Therefore, according to the applicants, the inventive device for acoustic testing of anti-noise is a new technical solution that belongs to the class of devices.

The correctness of the claimed technical solutions for acoustic tests of anti-noise is confirmed in the study of the acoustic effectiveness of five samples of personal protective equipment against low-frequency noise and infrasound. The inventive device, in comparison with the previously known, provided the possibility of acoustic testing of anti-noise in the infrasonic range, increased the objectivity of the test results by monitoring the constancy of the acoustic field over their entire length (through the use of a control microphone), as well as through the use of an external suspension, allowing rotating the device around its axis, sequentially fix it in several positions, and, in addition, more accurate and convenient positioning of the device and test emogo insert hearing protector in the sound field through the implementation of the possibility of adjusting the device stand height.

The inventive device for acoustic testing of anti-noise is industrially applicable, because it can be implemented by enterprises (organizations) of the industry involved in the design, testing and certification of anti-noise.

Claims (16)

1. A device for acoustic tests of anti-noise, the cylindrical body of which is made of non-magnetic metal, equipped with: a measuring microphone-condenser-type pressure receiver located in the plane of one of the bases of the cylinder so that the central axis of the microphone coincides with the center of its diaphragm and with the central axis of the cylinder; a support plate protruding from the center of the cylinder along its generatrix at right angles to the central axis, to the free end of which a rubber collar is connected; elastic mount to support the device in the acoustic field; a device, a soundproofing ring and marks on the end ends of the device for fixing anti-noise, providing hermetic closure of the device; a removable static pressure equalization tube that fits snugly to the bottom of the cylinder after fixing the anti-noise, characterized in that it additionally includes a condenser-type control microphone-receiver for monitoring the immutability of the acoustic field parameters, and an external suspension, allowing, rotating the device around the axis, sequentially fix it in several positions, and the stand of the device is equipped with a screw mechanism that allows you to adjust its height. 2. The device according to p. 1, characterized by the inclusion of additional measuring and control microphones for acoustic testing simultaneously of two cups (caps) of noise-protective headphones. 3. The device according to claim 1, characterized in that the measuring and control microphones have a nominal diameter of 12 mm or 24 mm. 4. The device according to p. 1, characterized in that it further comprises an automatic control unit for the acoustic field parameters connected to the output of the control microphone and calculating the difference between the average values of sound pressure in each of the octave bands during the test of anti-noise with similar average values of sound pressure in the absence of anti-noise device, with the formation and issuance of a signal about violation of the conditions of acoustic tests when the module exceeds the difference in the average values of sound pressure Ichin 1 dB. 5. The device according to claim 1, characterized in that the control microphone is located at a distance of 50 mm from the measuring microphone. 6. The device according to claim 1, characterized in that the external suspension connected to the elastic mount allows rotating the device around the axis to sequentially fix it in six positions with a resolution of 60 °. 7. The device according to claim 1, characterized in that the coefficient of sound attenuation from the back of the measuring and control microphones exceeds 15 dB. 8. The device according to p. 1, characterized in that the measuring and control microphones provide measurement of sound pressure levels in the frequency range from 2 to 16000 Hz. 9. The device according to p. 1, characterized in that the dynamic range of the measuring and control microphones is at least 80 dB. 10. The device according to p. 1, characterized in that the non-uniformity of the amplitude-frequency characteristics of the measuring and control microphones within the operating frequency range is not more than ± 1 dB. 11. The device according to claim 1, characterized in that the sensitivity of the measuring and control microphones within the operating frequency range must be at least 50 mV / Pa. 12. The device according to p. 1, characterized in that its housing is made of polymethyl methacrylate. 13. The device according to p. 1, characterized in that its housing is made of polycarbonate. 14. The device according to claim 1, characterized in that its housing is made of polyvinyl chloride. 15. The device according to claim 1, characterized in that its housing is made of polystyrene. 16. The device according to p. 1, characterized in that the outputs of the measuring and control microphone are equipped with additional connectors that allow you to connect an automatic clamp recorded levels of sound pressure with recording information in a drive with non-volatile memory.

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