CN103675104A - Method and device for measuring random incidence sound-absorbing coefficient/sound-absorbing quantity of material - Google Patents

Abstract

The invention relates to a method and device for measuring random incidence sound-absorbing coefficient/sound-absorbing quantity of a material. The method comprises the following steps: 1) a signal transmitter module sends out a frequency sweeping sound signal into a reverberation room; 2) a signal acquisition module acquires sound pressure signals of the reverberation room before and after the placing of a test piece respectively; 3) a signal processing module calculates the impulse responses of the reverberation room before and after the placing of the test piece respectively, the sound pressure level attenuation and fitting data of each frequency band, and reverberation time, and calculates the sound-absorbing coefficient/sound-absorbing quantity of the frequency band of the test piece and the noise reduction index NRC; 4) a result display module displays the sound pressure level attenuation and the matched curve of the frequency band, a reverberation time list, and a sound-absorbing coefficient/sound-absorbing quantity list and curve; 5) a storage and statement generation module stores the impulse responses and the results, and generates a test report; 6) an off-line analysis module can perform in-depth signal analysis by invoking the stored impulse responses. The method and device have the advantages of high precision, high speed, integrated data processing and the like.

Description

The measuring method of material random incidence acoustical absorption coefficient or absorption and measurement mechanism thereof

Technical field

The present invention relates to a kind of measuring technique of field of acoustics, especially relate to a kind of material random incidence acoustical absorption coefficient or absorption measuring method and measurement mechanism thereof.

Background technology

The conventional random incidence acoustical absorption coefficient of the sound absorbing capabilities of material in actual sound field or absorption represent.Reverberation room method utilizes the relation of reverberation time and absorption to measure random incidence acoustical absorption coefficient or the absorption of material.It is measured sound field and relatively approaches actual sound field, and the acoustical absorption coefficient that therefore conventional this method records or absorption are as the foundation of hall acoustic design and environmental noise abatement design.Measure exactly material random incidence acoustical absorption coefficient or absorption significant to development and the engineering practice of room acoustics design and environmental noise abatement technology.Traditional measurement equipment is generally to utilize steady-state noise to interrupt method, and the reverberation time is measured on frequency band ground one by one, and manually calculates acoustical absorption coefficient and editor's test report.The sound pressure level die-away curve that utilizes steady-state noise interruption method to obtain is subject to the impact of loudspeaker initial phase, has randomness, must be through the average ability of measurement result is repeatedly eliminated to randomness substantially.These problems have caused traditional measurement method to have the shortcoming that testing efficiency is low, precision is poor.

Summary of the invention

Object of the present invention is exactly accurately changing fast and automatically of providing in order to overcome the defect that above-mentioned existing measuring technique the exists material random incidence acoustical absorption coefficient that degree is high or measuring method and the measurement mechanism thereof of absorption.

Object of the present invention can be achieved through the following technical solutions:

A measuring method for material random incidence acoustical absorption coefficient or absorption, is characterized in that, comprises the following steps:

1) signal emission module is sent frequency sweep acoustical signal by digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connecting successively in reverberation chamber;

2) signal acquisition module, by the microphone, prime amplifier, analog-to-digital conversion card and the digital signal reception unit that connect successively, gathers respectively the empty chamber of reverberation chamber and puts into the sound pressure signal after test specimen, and sending it to signal processing module;

3) signal processing module calculates respectively the empty chamber of reverberation chamber and puts into the impulse response after test specimen, sound pressure level decay and fitting data and the reverberation time of each frequency band, wherein each frequency band comprises octave band and 1/3 octave band, utilize Sabine formula to calculate acoustical absorption coefficient or the absorption of institute's each frequency band of test block, the acoustical absorption coefficient that is 250Hz, 500Hz, 1000Hz, 2000Hz to centre frequency is averaging the noise reduction index NRC that can obtain test specimen, and data processed result is sent to result display module and storage and report generation module;

4) result display module is presented at sound pressure level decay and matched curve, reverberation time list and acoustical absorption coefficient or absorption list and the curve of sound pressure signal curve that reverberation chamber measures, pulse respond, each frequency band;

5) sound pressure signal that storage and report generation module stores collect in reverberation chamber, impulse response, reverberation time calculate result, acoustical absorption coefficient or absorption result of calculation, and generate test report;

6) off-line analysis module is called sound pressure signal and the impulse response of having stored, and carries out deep signal analysis.

The computation process of described reverberation time is as follows:

11) by the impulse response of the sound pressure signal collecting and Digital Sweep Signal cross correlation acquisition reverberation chamber;

12) impulse response is blocked in time domain according to the criterion of setting, obtained effective impulse response;

13) impulse response after blocking is carried out to the impulse response that filtering obtains each frequency band;

14) squared to the impulse response of each frequency band, obtain Energy impulse response function;

15) utilize Schroder to fall integral method Energy impulse response function is fallen to integration, be normalized again, and get common logarithm and be multiplied by again 10 and obtain sound pressure level die-away curve, according to the requirement of < < GB/T50076-2013 room reverberation time measurement standard > >, curve between sound pressure level decline curve-5～-35dB is carried out to linear fit by least square method, obtain the slope of sound pressure level die-away curve, further calculate the reverberation time of each frequency band.

Described acoustical absorption coefficient or the computation process of absorption are as follows:

The acoustical absorption coefficient α of each frequency band _sreverberation time by each frequency band calculates by following formula: ${\mathrm{\&alpha;}}_s=\frac{55.3V}{C\&CenterDot;S}(\frac{1}{T_{60-2}}-\frac{1}{T_{60-1}}),$ Absorption A calculates by following formula: $A=\frac{55.3V}{C\&CenterDot;n}(\frac{1}{T_{60-2}}-\frac{1}{T_{60-1}}),$ Wherein V is reverberation chamber volume; C is THE VELOCITY OF SOUND IN AIR, C=331.5+0.6t, and t is environment temperature; S is test specimen area; T _60-2it is the reverberation time of putting into after test specimen; L _60-1it is the reverberation time of putting into before test specimen; A is the absorption of single body; N is test specimen unit number.

A measurement mechanism for the measuring method of material random incidence acoustical absorption coefficient or absorption, is characterized in that, comprises signal emission module, signal acquisition module, signal processing module, result display module, storage and report generation module and off-line analysis module; Described signal emission module is responsible for sending frequency sweep acoustical signal in reverberation chamber; Described signal processing module is connected with signal emission module, signal acquisition module, result display module, storage and report generation module respectively, and real-time processing, storage and the test report of being responsible for signal generate; Described off-line analysis module is connected with signal processing module, result display module, storage and report generation module, and processed offline, storage and the test report of being responsible for signal generate.

Described signal emission module comprises successively digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connecting, and completes to the task of launching frequency sweep acoustical signal in reverberation chamber.

Described signal acquisition module comprises microphone, prime amplifier, analog-to-digital conversion card and the digital signal reception unit connecting successively, completes the task that in reverberation chamber, sound pressure signal gathers, and collection signal is sent to signal processing module.

While selecting real-time measurement pattern, select signal transmission channel and acquisition channel; Test operating mode select progressively put into test specimen formerly or empty chamber formerly; Measure the item is selected acoustical absorption coefficient or absorption; If select acoustical absorption coefficient need to input test specimen area, if select sound absorber need to input test specimen unit number; Initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume are blocked in the transmit initial frequency of duration, collection signal duration, sample frequency, signal amplitude, swept-frequency signal and cutoff frequency, impulse response of input.

While selecting off-line analysis pattern, utilize off-line analysis module, impulse response or reverberation time when importing the empty chamber stored and having test specimen in reverberation chamber are calculated result, and initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume are blocked in input sample frequency, impulse response.

Described result display module comprises collection acoustic pressure curve display unit, impulse response display unit, T ₆₀curve display unit, reverberation time and sound absorption data display unit;

Wherein, described collection acoustic pressure curve display unit shows collection acoustic pressure curve map, and described impulse response display unit shows acoustic pressure pulse response curve, described T ₆₀curve display unit shows OBSPL die-away curve and matched curve, 1/3 octave band sound pressure level die-away curve and matched curve thereof, and described reverberation time and sound absorption data display unit show reverberation time list, acoustical absorption coefficient or absorption list and the curve of octave band or 1/3 octave band.

Described storage and report generation module comprise sound pressure signal storage unit, impulse response storage unit, reverberation time calculating result store unit, acoustical absorption coefficient or absorption result of calculation storage unit, detecting information edit cell, test report generation unit, test report storage unit, test report print unit;

Wherein, the sound pressure signal that described sound pressure signal cell stores collects in reverberation chamber, described impulse response cell stores acoustic pressure pulse response, the described reverberation time calculates the result store unit storage reverberation time and calculates result, described acoustical absorption coefficient or absorption result of calculation cell stores acoustical absorption coefficient or absorption result of calculation, described detecting information edit cell editor detecting information, described test report generation unit generates test report, described test report cell stores test report, described test report print unit printing test report.

Compared with prior art, the present invention has the following advantages:

1, adopt impulse response and Schroder to fall integral method, sound pressure level decline curve after one-shot measurement can obtain and be equivalent to traditional steady-state noise and interrupt method repeatedly (in theory for many times), measurement result was average, efficiency and the precision of parameter reverberation time in the middle of measuring have greatly been improved, because impulse response is the build-in attribute in room, not the impact of tested person acoustical signal.Measure the reverberation time of material 1/3 octave band in 100Hz-5000Hz frequency range, the time that classic method need to approximately 120 minutes, and the present invention only needs the time of 6 minutes.

2, there is data acquisition, storage, Treatment Analysis integrated, function with scene generation test report, improve the automatization level of measuring process, avoided the error that in traditional measurement method, artificial treatment data produce and mistake, significantly improved precision and the efficiency measured.Classic method can only obtain reverberation time data, acoustical absorption coefficient or absorption, and test report must artificial calculate and editor, and approximately 4 hours consuming time, all test processs need to be approximately 6 hours, and the present invention measures and omnidistancely only needs 10 minutes.

3, measuring process and result visualization, tester can tentatively judge the validity of test result by observing the form of impulse response and each sound control decline curve, find to cut the problem of ripple, the poor test result that leads to errors of sound field diffusion level, adjust in time testing scheme, obtain correct test result.And conventional test methodologies only provides the reverberation time measurement data of each frequency band, tester cannot judge the validity of test result, cannot guarantee that test result is correct.

4, off-line analysis module can be analysed in depth acoustic pressure and the impulse response data of storage.If it is abnormal that tester finds test result, can reanalyse test data, give up abnormal data, obtain rational test result.Traditional measuring system generally can not be stored data, cannot check test result, once there is the situation that test result is abnormal, test material is transported out of laboratory, just may cause test accident.

5, measuring equipment all adopts modular design, and test interface is simple and clear, convenient operation.

Accompanying drawing explanation

Fig. 1 is the structural representation of measurement mechanism of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

Embodiment

As shown in Figure 1, the measurement mechanism of material random incidence acoustical absorption coefficient, comprises signal emission module 11, signal acquisition module 12, signal processing module 13, result display module 14, storage and report generation module 15 and off-line analysis module 16.Described signal emission module 11 is responsible for sending frequency sweep acoustical signal in reverberation chamber, described signal processing module 13 is connected with signal emission module 11, signal acquisition module 12, result display module 14, storage and report generation module 15 respectively, described off-line analysis module 16 is connected with signal processing module 13, and signal processing module 13 is connected with result display module 14, storage and report generation module 15.

Described signal emission module 11 comprises successively digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connecting, and completes to the task of launching frequency sweep acoustical signal in reverberation chamber.

Described signal acquisition module 12 comprises microphone, analog-to-digital conversion card, prime amplifier and the digital signal reception unit connecting successively, completes the task that in reverberation chamber, sound pressure signal gathers, and collection signal is sent to signal processing module.

Described signal processing module 13 calculates respectively the empty chamber of reverberation chamber and puts into the sound pressure level decay of impulse response after test specimen, each frequency band and fitting data, reverberation time, wherein each frequency band comprises octave band and 1/3 octave band, utilize Sabine formula to calculate acoustical absorption coefficient or the absorption of institute's each frequency band of test block, the acoustical absorption coefficient that is 250Hz, 500Hz, 1000Hz, 2000Hz to centre frequency is averaging the noise reduction index NRC that can obtain test specimen, and result is sent to result display module 14 and storage and report generation module 15.

While selecting real-time measurement pattern, select signal transmission channel and acquisition channel, the select progressively of test operating mode put into test specimen formerly or empty chamber formerly, measure the item is selected acoustical absorption coefficient or absorption, if select acoustical absorption coefficient need to input test specimen area, if select absorption need to input test specimen unit number; Initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume are blocked in the transmit initial frequency of duration, collection signal duration, sample frequency, signal amplitude, swept-frequency signal and cutoff frequency, impulse response of input.

While selecting off-line analysis pattern, utilize off-line analysis module 16, impulse response or reverberation time when importing the empty chamber stored and having test specimen in reverberation chamber are calculated result, and initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume information are blocked in input sample frequency, impulse response.

Described result display module 14 comprises collection acoustic pressure curve display unit, impulse response display unit, T ₆₀curve display unit, reverberation time and sound absorption data display unit;

Wherein, described collection acoustic pressure curve display unit shows collection acoustic pressure curve map, and described impulse response display unit shows acoustic pressure pulse response diagram, described T ₆₀curve display unit shows OBSPL die-away curve and matched curve, 1/3 octave band sound pressure level die-away curve and matched curve thereof, and described reverberation time and sound absorption data display unit show reverberation time list, acoustical absorption coefficient or absorption list and the curve of octave band or 1/3 octave band.

Described storage and report generation module 15 comprise sound pressure signal storage unit, impulse response storage unit, reverberation time calculating result store unit, acoustical absorption coefficient or absorption result of calculation storage unit, detecting information edit cell, test report generation unit, test report storage unit, test report print unit;

Wherein, the sound pressure signal that described sound pressure signal cell stores collects in reverberation chamber, described impulse response cell stores acoustic pressure pulse response, the described reverberation time calculates the result store unit storage reverberation time and calculates result, described acoustical absorption coefficient or absorption result of calculation cell stores acoustical absorption coefficient or absorption result of calculation, described detecting information edit cell editor detecting information, described test report generation unit generates test report, described test report cell stores test report, described test report print unit printing test report.

Measuring process of the present invention is:

1) parameter setting: the thick polyurethane sponge of 25.4mm of giving an example, select real-time measurement pattern; Select signal transmission channel and acquisition channel; Test operating mode select progressively test specimen formerly, to select acoustical absorption coefficient, input test specimen area be 12.85m to measure the item ², the input duration that transmits is that 10s, collection signal duration are that 20s, sample frequency are that 44100Hz (should be greater than higher cutoff frequency at least 2 times), signal amplitude are 1, the initial frequency of swept-frequency signal is that 20Hz and cutoff frequency are 20kHz, it is 9s and closing time to be that 20s, pulse due in criterion are that 10dB, environment temperature are that 25 ℃, reverberation chamber volume are 268m that initial time is blocked in impulse response ³;

2) sound absorption form editor: the contents such as input test report heading, client, project are responsible for, telephone number, mailing address, postcode, measuring unit, tester, test duration, project brief;

3) working procedure, by the reverberation time of 1/3 octave band after measuring respectively empty chamber and putting into test specimen, utilizes formula

the acoustical absorption coefficient or the absorption that calculate institute's each frequency band of test block, wherein V is reverberation chamber volume 268m ³; C is THE VELOCITY OF SOUND IN AIR C=331.5+0.6*25=346.5; S is test specimen area 12.85m ²; T _60-2it is the reverberation time of putting into after test specimen; T _60-1it is the reverberation time of not putting into before test specimen; The acoustical absorption coefficient that is 250Hz, 500Hz, 1000Hz, 2000Hz to centre frequency is averaging the noise reduction index (NRC) that can obtain test specimen, and acoustical absorption coefficient measurement result is as following table:

Frequency (Hz)	Random incidence acoustical absorption coefficient
		100	0.06
125	0.11
		160	0.15

200	0.17
		250	0.23
315	0.30
		400	0.39
500	0.45
		630	0.48
800	0.52
		1000	0.56
1250	0.62
		1600	0.67
2000	0.69
		2500	0.71
3150	0.75
		4000	0.79
5000	0.83

And calculate noise reduction index (NRC) result for (0.23+0.45+0.56+0.69)/4=0.48.

4) report generation module is after obtaining above-mentioned numerical value, and the detecting information that editor is inputted by tester, completes the task that test report generates, stores and print.

Claims (10)

1. a measuring method for material random incidence acoustical absorption coefficient or absorption, is characterized in that, comprises the following steps:

1) signal emission module is sent frequency sweep acoustical signal by digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connecting successively in reverberation chamber;

2) signal acquisition module, by the microphone, prime amplifier, analog-to-digital conversion card and the digital signal reception unit that connect successively, gathers respectively the empty chamber of reverberation chamber and puts into the sound pressure signal after test specimen, and sending it to signal processing module;

3) signal processing module calculates respectively the empty chamber of reverberation chamber and puts into the impulse response after test specimen, sound pressure level decay and fitting data and the reverberation time of each frequency band, wherein each frequency band comprises octave band and 1/3 octave band, utilize Sabine formula to calculate acoustical absorption coefficient or the absorption of institute's each frequency band of test block, the acoustical absorption coefficient that is 250Hz, 500Hz, 1000Hz, 2000Hz to centre frequency is averaging the noise reduction index NRC that can obtain test specimen, and data processed result is sent to result display module and storage and report generation module;

4) result display module is presented at sound pressure level decay and matched curve, reverberation time list and acoustical absorption coefficient or absorption list and the curve of sound pressure signal curve that reverberation chamber measures, pulse respond, each frequency band;

5) sound pressure signal that storage and report generation module stores collect in reverberation chamber, impulse response, reverberation time calculate result, acoustical absorption coefficient or absorption result of calculation, and generate test report;

6) off-line analysis module is called sound pressure signal and the impulse response of having stored, and carries out deep signal analysis.

2. the measuring method of a kind of material random incidence acoustical absorption coefficient according to claim 1 or absorption, is characterized in that, the computation process of described reverberation time is as follows:

11) by the impulse response of the sound pressure signal collecting and Digital Sweep Signal cross correlation acquisition reverberation chamber;

12) impulse response is blocked in time domain according to the criterion of setting, obtained effective impulse response;

13) impulse response after blocking is carried out to the impulse response that filtering obtains each frequency band;

14) squared to the impulse response of each frequency band, obtain Energy impulse response function;

15) utilize Schroder to fall integral method Energy impulse response function is fallen to integration, be normalized again, and get common logarithm and be multiplied by again 10 and obtain sound pressure level die-away curve, according to the requirement of < < GB/T50076-2013 room reverberation time measurement standard > >, curve between sound pressure level decline curve-5～-35dB is carried out to linear fit by least square method, obtain the slope of sound pressure level die-away curve, further calculate the reverberation time of each frequency band.

3. the measuring method of a kind of material random incidence acoustical absorption coefficient according to claim 1 or absorption, is characterized in that, described acoustical absorption coefficient or the computation process of absorption are as follows:

The acoustical absorption coefficient α of each frequency band _sreverberation time by each frequency band calculates by following formula: ${\mathrm{\&alpha;}}_s=\frac{55.3V}{C\&CenterDot;S}(\frac{1}{T_{60-2}}-\frac{1}{T_{60-1}}),$ Absorption A calculates by following formula: $A=\frac{55.3V}{C\&CenterDot;n}(\frac{1}{T_{60-2}}-\frac{1}{T_{60-1}}),$ Wherein V is reverberation chamber volume; C is THE VELOCITY OF SOUND IN AIR, C=331.5+0.6t, and t is environment temperature; S is test specimen area; T _60-2it is the reverberation time of putting into after test specimen; L _60-1it is the reverberation time of putting into before test specimen; A is the absorption of single body; N is test specimen unit number.

4. a measurement mechanism that implements the claims the measuring method of material random incidence acoustical absorption coefficient described in 1 or absorption, it is characterized in that, comprise signal emission module, signal acquisition module, signal processing module, result display module, storage and report generation module and off-line analysis module; Described signal emission module is responsible for sending frequency sweep acoustical signal in reverberation chamber; Described signal processing module is connected with signal emission module, signal acquisition module, result display module, storage and report generation module respectively, and real-time processing, storage and the test report of being responsible for signal generate; Described off-line analysis module is connected with signal processing module, and signal processing module is connected with result display module, storage and report generation module, and processed offline, storage and the test report of being responsible for signal generate.

5. the measurement mechanism of the measuring method of material random incidence acoustical absorption coefficient according to claim 4 or absorption, it is characterized in that, described signal emission module comprises successively digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connecting, and completes to the task of launching frequency sweep acoustical signal in reverberation chamber.

6. the measurement mechanism of the measuring method of material random incidence acoustical absorption coefficient according to claim 4 or absorption, it is characterized in that, described signal acquisition module comprises microphone, prime amplifier, analog-to-digital conversion card and the digital signal reception unit connecting successively, complete the task that in reverberation chamber, sound pressure signal gathers, and collection signal is sent to signal processing module.

7. the measurement mechanism of the measuring method of material random incidence acoustical absorption coefficient according to claim 4 or absorption, is characterized in that, while selecting real-time measurement pattern, selects signal transmission channel and acquisition channel; Test operating mode select progressively put into test specimen formerly or empty chamber formerly; Measure the item is selected acoustical absorption coefficient or absorption; If select acoustical absorption coefficient need to input test specimen area, if select sound absorber need to input test specimen unit number; Initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume are blocked in the transmit initial frequency of duration, collection signal duration, sample frequency, signal amplitude, swept-frequency signal and cutoff frequency, impulse response of input.

8. the measurement mechanism of the measuring method of material random incidence acoustical absorption coefficient according to claim 4 or absorption, it is characterized in that, while selecting off-line analysis pattern, utilize off-line analysis module, impulse response or reverberation time when importing the empty chamber stored and having test specimen in reverberation chamber are calculated result, and initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume are blocked in input sample frequency, impulse response.

9. the measurement mechanism of the measuring method of material random incidence acoustical absorption coefficient according to claim 4 or absorption, is characterized in that, described result display module comprises collection acoustic pressure curve display unit, impulse response display unit, T ₆₀curve display unit, reverberation time and sound absorption data display unit;

Wherein, described collection acoustic pressure curve display unit shows collection acoustic pressure curve map, and described impulse response display unit shows acoustic pressure pulse response curve, described T ₆₀curve display unit shows OBSPL die-away curve and matched curve, 1/3 octave band sound pressure level die-away curve and matched curve thereof, and described reverberation time and sound absorption data display unit show reverberation time list, acoustical absorption coefficient or absorption list and the curve of octave band or 1/3 octave band.

10. the measurement mechanism of the measuring method of material random incidence acoustical absorption coefficient according to claim 4 or absorption, it is characterized in that, described storage and report generation module comprise sound pressure signal storage unit, impulse response storage unit, reverberation time calculating result store unit, acoustical absorption coefficient or absorption result of calculation storage unit, detecting information edit cell, test report generation unit, test report storage unit, test report print unit;

Wherein, the sound pressure signal that described sound pressure signal cell stores collects in reverberation chamber, described impulse response cell stores acoustic pressure pulse response, the described reverberation time calculates the result store unit storage reverberation time and calculates result, described acoustical absorption coefficient or absorption result of calculation cell stores acoustical absorption coefficient or absorption result of calculation, described detecting information edit cell editor detecting information, described test report generation unit generates test report, described test report cell stores test report, described test report print unit printing test report.

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