CN103675104B - The measuring method of material random incidence acoustical absorption coefficient or absorption and measurement mechanism thereof - Google Patents

Abstract

The present invention relates to measuring method and the measurement mechanism thereof of a kind of material random incidence acoustical absorption coefficient or absorption, comprise the following steps: 1) signal emission module sends frequency sweep acoustical signal in reverberation chamber; 2) signal acquisition module gathers the empty room of reverberation chamber and the sound pressure signal after putting into test specimen respectively; 3) signal processing module calculates the empty room of reverberation chamber and the impulse response after putting into test specimen, the sound pressure level decay of each frequency band and fitting data and reverberation time respectively, utilizes Sabine formula to calculate the acoustical absorption coefficient of each frequency band of institute's test block or absorption and noise reduction index NRC; 4) result display module shows the sound pressure level decay of each frequency band and matched curve, reverberation time list and acoustical absorption coefficient or absorption list and curve; 5) to store and the impulse response of report generation module stores and result of calculation, and generate test report; 6) off-line analysis module can call the impulse response stored, and carries out deep signal analysis.The present invention has the advantages such as precision is high, speed is fast, data processing is integrated.

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 sound absorbing capabilities of material in actual sound field commonly uses random incidence acoustical absorption coefficient or absorption represents.Reverberation room method utilizes the relation of reverberation time and absorption to measure random incidence acoustical absorption coefficient or the absorption of material.It measures sound field relatively actual sound field, therefore the foundation that designs as iron carbonyl compound design and environmental noise abatement of the acoustical absorption coefficient that records of this method conventional or absorption.Measure exactly material random incidence acoustical absorption coefficient or absorption to the development of auditorium acoustical design and environmental noise abatement technology and engineering practice significant.Conventional measurement devices is generally utilize steady-state noise to interrupt method, and the reverberation time is measured on frequency band ground one by one, and artificial calculating acoustical absorption coefficient and editor's test report.The sound pressure level die-away curve utilizing steady-state noise method of interrupting to obtain is subject to the impact of loudspeaker initial phase, has randomness, has to pass through and substantially eliminate randomness to the average ability of repetitive measurement result.These problems result in traditional measurement method and have the shortcoming that testing efficiency is low, precision is poor.

Summary of the invention

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

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 sends frequency sweep acoustical signal by digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connected successively in reverberation chamber;

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

3) signal processing module calculates the empty room of reverberation chamber and the impulse response after putting into test specimen, the sound pressure level decay of each frequency band and fitting data and reverberation time respectively, wherein each frequency band comprises octave band and 1/3 octave band, Sabine formula is utilized to calculate acoustical absorption coefficient or the absorption of each frequency band of institute's test block, the noise reduction index NRC that can obtain test specimen is averaging to the acoustical absorption coefficient that centre frequency is 250Hz, 500Hz, 1000Hz, 2000Hz, 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 signal curve that reverberation chamber measures, pulse respond, the sound pressure level decay of each frequency band and matched curve, reverberation time list and acoustical absorption coefficient or absorption list and curve;

5) to store and sound pressure signal that report generation module stores collects 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 calls the sound pressure signal and impulse response that have stored, carries out deep signal analysis.

The computation process of described reverberation time is as follows:

11) sound pressure signal collected and Digital Sweep signal cross-correlation are obtained the impulse response of reverberation chamber;

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

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

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

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

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

The acoustical absorption coefficient α of each frequency band _sfollowing formulae discovery is pressed by the reverberation time of each frequency band: ${\mathrm{\α}}_s=\frac{55.3V}{C\·S}(\frac{1}{T_{60-2}}-\frac{1}{T_{60-1}}),$ Absorption A is by following formulae discovery: $A=\frac{55.3V}{C\·n}(\frac{1}{T_{60-2}}-\frac{1}{T_{60-1}}),$ Wherein V is reverberation chamber volume; C is THE VELOCITY OF SOUND IN AIR, and C=331.5+0.6t, t are environment temperatures; S is test specimen area; T _60-2it is the reverberation time after putting into test specimen; L _60-1it is the reverberation time before putting into 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 in reverberation chamber, send frequency sweep acoustical signal; Described signal processing module respectively with signal emission module, signal acquisition module, result display module, storage and report generation model calling, be responsible for the real-time process of signal, storage and test report and generate; Described off-line analysis module and signal processing module, result display module, storage and report generation model calling, be responsible for the processed offline of signal, storage and test report and generate.

Described signal emission module comprises the digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker that connect successively, has carried out to launch the task of frequency sweep acoustical signal in reverberation chamber.

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

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

When selecting off-line analysis pattern, utilize off-line analysis module, impulse response when importing the empty room that stored and have test specimen in reverberation chamber or reverberation time calculate result, and input sample frequency, impulse response block initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume.

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

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

Described storage and report generation module comprise sound pressure signal storage unit, impulse response storage unit, reverberation time calculating result storage 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 result cell stores reverberation time calculating 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, impulse response and Schroder is adopted to fall integral method, one-shot measurement can obtain be equivalent to traditional steady-state noise interrupt method repeatedly (in theory for many times) measurement result average after sound pressure level decline curve, drastically increase efficiency and the precision of parameter reverberation time in the middle of measuring, 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, classic method needs the time of about 120 minutes, and the present invention only needs the time of 6 minutes.

2, there is data acquisition, storage, Treatment Analysis integration, the function of test report is generated with scene, improve the automatization level of measuring process, avoid error and mistake that in traditional measurement method, artificial treatment data produce, significantly improve precision and the efficiency of measurement.Classic method can only obtain reverberation time data, acoustical absorption coefficient or absorption, and test report must manually calculate and editor, and about 4 hours consuming time, whole test process needed about 6 hours, and the present invention measures whole process only needs 10 minutes.

3, measuring process and result visualization, tester tentatively can judge the validity of test result by the form of observing impulse response and each sound control decline curve, find the problem of cutting ripple, sound field diffusion level difference leads to errors test result, timely adjustment testing scheme, obtains 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 ensure that test result is correct.

4, off-line analysis module can be analysed in depth the acoustic pressure stored and impulse response data.If tester finds that test result is abnormal, can reanalyse test data, give up abnormal data, obtain rational test result.Traditional measuring system generally can not store data, cannot check test result, once generation test result is abnormal, test material is transported out of the situation in 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 in reverberation chamber, send frequency sweep acoustical signal, described signal processing module 13 respectively with signal emission module 11, signal acquisition module 12, result display module 14, to store and report generation module 15 is connected, described off-line analysis module 16 is connected with signal processing module 13, signal processing module 13 and result display module 14, to store and report generation module 15 is connected.

Described signal emission module 11 comprises the digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker that connect successively, has carried out to launch the task of frequency sweep acoustical signal in reverberation chamber.

Described signal acquisition module 12 comprises the microphone, analog-to-digital conversion card, prime amplifier and the digital signal reception unit that connect successively, has carried out 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 the empty room of reverberation chamber and the impulse response after putting into test specimen, the sound pressure level decay of each frequency band and fitting data, reverberation time respectively, wherein each frequency band comprises octave band and 1/3 octave band, Sabine formula is utilized to calculate acoustical absorption coefficient or the absorption of each frequency band of institute's test block, the noise reduction index NRC that can obtain test specimen is averaging to the acoustical absorption coefficient that centre frequency is 250Hz, 500Hz, 1000Hz, 2000Hz, and result is sent to result display module 14 and store and report generation module 15.

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

When selecting off-line analysis pattern, utilize off-line analysis module 16, impulse response when importing the empty room that stored and have test specimen in reverberation chamber or reverberation time calculate result, and input sample frequency, impulse response block initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume information.

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

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

Described storage and report generation module 15 comprise sound pressure signal storage unit, impulse response storage unit, reverberation time calculating result storage 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 result cell stores reverberation time calculating 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) optimum configurations: the polyurethane sponge that citing 25.4mm is thick, selects real-time measurement pattern; Select signal transmission channel and acquisition channel; Measurement condition select progressively test specimen formerly, measure the item selects acoustical absorption coefficient, input test specimen area is 12.85m ², input transmits that duration is 10s, collection signal duration is 20s, sample frequency is 44100Hz (should be greater than most higher cutoff frequency at least 2 times), signal amplitude is 1, the initial frequency of swept-frequency signal be 20Hz and cutoff frequency is 20kHz, it be 9s and closing time is 20s that initial time is blocked in impulse response, pulse due in criterion is 10dB, environment temperature is 25 DEG C, reverberation chamber volume is 268m ³;

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

3) working procedure, by measuring empty room respectively and putting into reverberation time of 1/3 octave band after test specimen, utilizes formula calculate acoustical absorption coefficient or the absorption of each frequency band of institute's 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 after putting into test specimen; T _60-1it is the reverberation time before not putting into test specimen; Be averaging the noise reduction index (NRC) that can obtain test specimen to the acoustical absorption coefficient that centre frequency is 250Hz, 500Hz, 1000Hz, 2000Hz, 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, after obtaining above-mentioned numerical value, edits the detecting information inputted by tester, completes the task that test report generates, stores and print.

Claims (8)

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 sends frequency sweep acoustical signal by digital signal generation unit, digital-to-analog conversion card, power amplifier and the loudspeaker connected successively in reverberation chamber;

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

3) signal processing module calculates the empty room of reverberation chamber and the impulse response after putting into test specimen, the sound pressure level decay of each frequency band and fitting data and reverberation time respectively, wherein each frequency band comprises octave band and 1/3 octave band, Sabine formula is utilized to calculate acoustical absorption coefficient or the absorption of each frequency band of institute's test block, the noise reduction index NRC that can obtain test specimen is averaging to the acoustical absorption coefficient that centre frequency is 250Hz, 500Hz, 1000Hz, 2000Hz, 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 signal curve that reverberation chamber measures, pulse respond, the sound pressure level decay of each frequency band and matched curve, reverberation time list and acoustical absorption coefficient or absorption list and curve;

5) to store and sound pressure signal that report generation module stores collects 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 calls the sound pressure signal and impulse response that have stored, 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, it is characterized in that, the computation process of described reverberation time is as follows:

11) sound pressure signal collected and frequency sweep acoustical signal cross-correlation are obtained the impulse response of reverberation chamber;

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

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

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

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

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 as follows:

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

4. one kind implements the claims the measurement mechanism of 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 in reverberation chamber, send frequency sweep acoustical signal; Described signal processing module respectively with signal emission module, signal acquisition module, result display module, storage and report generation model calling, be responsible for the real-time process of signal, storage and test report and generate; Described off-line analysis module is connected with signal processing module, signal processing module and result display module, storage and report generation model calling, is responsible for the processed offline of signal, storage and test report and generates.

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

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, when selecting off-line analysis pattern, utilize off-line analysis module, impulse response when importing the empty room that stored and have test specimen in reverberation chamber or reverberation time calculate result, and input sample frequency, impulse response block initial sum closing time, pulse due in criterion, environment temperature, reverberation chamber volume.

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

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

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, described storage and report generation module comprise sound pressure signal storage unit, impulse response storage unit, reverberation time calculating result storage 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 result cell stores reverberation time calculating 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.