CN101419794B - Infrasonic wave acoustic energy aggregation method by ellipsoid body - Google Patents
Infrasonic wave acoustic energy aggregation method by ellipsoid body Download PDFInfo
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- CN101419794B CN101419794B CN2008101531820A CN200810153182A CN101419794B CN 101419794 B CN101419794 B CN 101419794B CN 2008101531820 A CN2008101531820 A CN 2008101531820A CN 200810153182 A CN200810153182 A CN 200810153182A CN 101419794 B CN101419794 B CN 101419794B
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Abstract
The invention relates to a spheroid infrasonic wave sound energy binding method which comprises the steps: an acoustic resonatron, an assembly sound source and an acoustic resonatron are designed; a spheroid infrasonic wave sound energy binding chamber is designed; the position of a sound source focus and an infrasonic wave sound field reference point in the spheroid infrasonic wave sound energy binding chamber are determined; the sound source and the acoustic resonatron which are assembled into a whole as well as the measured object are fixed; when the sound source is connected, the infrasonic wave generated by the sound source is resonantly vibrated by the air in the acoustic resonatron, is radiated in the spheroid, and forms an energy binding infrasonic wave sound field in the right hemisphere space in the spheroid. The invention adopts the sound source with less sound output, and the strength of the infrasonic wave sound field which is set up by a plurality of times of the sound source is generated by the binding energy in the acoustic resonatron and the sound field in the spheroid. The sound pressure level in the energy binding sound field in the spheroid is 20-30dB higher than that of the sound source in a free sound field. The method can be used for testing the influence degree of high strength noise on the human body as well as animal and plant life or protecting the human body as well as animal and plant life from being affected by the high strength noise by the researchers, and provides reliable and effective acoustics environment for the experiment of the researchers.
Description
Technical field
The present invention relates to testing the required method that obtains strong sound field, particularly a kind of in order to study infrasonic wave to mankind, animal, plant and various raw-material influence, and need the infrasonic infrasonic wave acoustic energy aggregation method by ellipsoid body of establishment high strength.
Background technology
There is a large amount of infrasonic waves at occurring in nature, as earthquake, tsunami, blast etc.At large-scale weapon explosion time, can produce powerful shock wave, wherein infrasonic composition is also very big.The development of modern science and technology expands to every field, and subaudio weapon also becomes one of modern weapons.
Have bibliographical information to claim, high-intensity infrasonic wave is very big for the mankind's life and health harm, and the infrasonic wave of varying strength can make human mood uneasiness, mentally deranged, body injury, on the point of dying even dead.But the infrasonic wave that studies show that certain intensity is useful for human beings'health, even can be used for the medical treatment to certain disease.
High strength time sound field is created in research, understands the infrasonic wave of different frequency, varying strength to personnel, animal, plant or the various raw-material situation that influences for the research of relevant R﹠D institution.The more important thing is, in case when our personnel suffered from the infrasonic rugged surroundings of high strength, how research was on the defensive, and makes the infrasonic wave disaster reach minimum to the degree of injury of people and thing.So how creating the high strength infrasonic wave sound field that can test for R﹠D institution is the important topic that the scientific research personnel faces.
Summary of the invention
Fundamental purpose of the present invention provides infrasonic wave acoustic cumulative method in a kind of spheroid, and this method is used the air in tube resonance principle, strengthens low frequency and subaudible sound radiation ability of loudspeaker.When inner air tube resonance, the sound output of sound pipe opening part can reach a very high sound pressure level.A focus of the openend of sound pipe importing ellipsoid body acoustic energy aggregation chamber, can be in a high-intensity infrasonic wave cumulative sound field of the indoor establishment of sound cumulative space.
The technical scheme that the present invention is taked for achieving the above object is: infrasonic wave acoustic energy aggregation method by ellipsoid body follows these steps to carry out:
1., design acoustic resonance pipe
At first calculate the length that formula: L=C/4F obtains the acoustic resonance pipe according to the pipe resonance frequency, wherein F is a setpoint frequency; C is the velocity of sound; L is the acoustic resonance length of tube; Select sound source then, design the diameter of acoustic resonance pipe according to the bore of sound source; Make the acoustic resonance pipe according to the design size of acoustic resonance length of tube and diameter again;
2., assembling sound source harmony resonatron
Sound source harmony resonatron is assembled into one, and wherein an end of acoustic resonance pipe is an openend, and the other end is connected with sound source;
3., design spheroid infrasonic wave acoustic cumulative chamber
Determine that at first setpoint frequency and spheroid major axis have following relational expression: F=C/2a * 6, obtain the design size of spheroid major axis then according to relational expression; Wherein F is a setpoint frequency; C is the velocity of sound; 2a is the major axis dimension of spheroid; Again according to two minor axis dimension of the size design spheroid of the sound source harmony resonatron that is assembled into one and measured object; Make spheroid infrasonic wave acoustic cumulative chamber according to the design size of spheroid major axis and two minor axises then;
4., determine the position of indoor sound source focus of spheroid infrasonic wave acoustic cumulative and infrasonic wave sound field reference point
At first according to oval semicoke apart from formula:
Determine earlier the indoor sound source focus of spheroid infrasonic wave acoustic cumulative to infrasonic wave sound field reference point apart from 2c, determine the position of sound source focus and infrasonic wave sound field reference point then according to the distance between 2 o'clock;
5., the sound source harmony resonatron and the measured object that fixedly are assembled into one
Place spheroid infrasonic wave acoustic cumulative indoor the sound source harmony resonatron and the measured object that are assembled into one, wherein the openend of acoustic resonance pipe places on the sound source focus, and measured object places reference point or centers in the infrasonic wave sound field cumulative zone of reference point;
6., connect the signal source of sound source after, the infrasonic wave that sound source produces at the ellipsoid internal radiation, forms cumulative infrasonic wave sound field by the air resonance in the acoustic resonance pipe in the right hemisphere space of spheroid.
The present invention has the following advantages: 1, the present invention can use sound the output source with small sound, the cumulative by sound field in sound pipe resonance and the ellipsoid produces the intensity that is several times as much as the infrasonic wave sound field that sound source can set up.The sound pressure level of spheroid cohesive energy sound field can be than the sound pressure level that sound source obtains in free found field high 20-30dB.2, adopt this method to do high intensity noise to human body, to the vegeto-animal influence degree test or the test of how to protect etc., provide reliable and effective acoustic enviroment for the researchist does experiment for the researchist.
Description of drawings
Fig. 1 is indoor sound source focus of spheroid infrasonic wave acoustic cumulative and infrasonic wave sound field reference point synoptic diagram.
Fig. 2 is sound source and straight acoustic resonance pipe assembling mode synoptic diagram.
Fig. 3 is sound source and curved acoustic resonance pipe assembling mode synoptic diagram.
Fig. 4 is that loudspeaker and the loudspeaker measured with sinusoidal signal in the test 1 add sound pipe frequency response curve comparison diagram.
Fig. 5 is that loudspeaker and the loudspeaker measured with sinusoidal signal in the test 2 add sound pipe frequency response curve comparison diagram.
Fig. 6 is acoustic resonance pipe and the microphone measuring position synoptic diagram that is combined into one with sound source among the embodiment.
Fig. 7 is a frequency response curve comparison diagram in the anechoic room of measuring with sinusoidal signal among the embodiment and in the spheroid.
Fig. 8 is in the anechoic room of measuring with the octave band pink noise among the embodiment and the interior frequency response curve comparison diagram of spheroid.
Fig. 9 is a measurement point synoptic diagram of measuring each octave band distribution of sound field in spheroid.
Figure 10 typical case octave band is at each measurement point test result sign picture.
Curve 1 among above Fig. 7,8 records in anechoic room for microphone places (1M1W condition) on the axis of sound pipe the place ahead.Curve 2 records in anechoic room for microphone places sound pipe openend center.Curve 3 places on the interior left focus of spheroid for the sound pipe openend, and microphone places on the right focus and records.
Embodiment
With reference to accompanying drawing, infrasonic wave acoustic energy aggregation method by ellipsoid body follows these steps to carry out:
1., design acoustic resonance pipe
At first calculate the length that formula: L=C/4F obtains the acoustic resonance pipe according to the pipe resonance frequency, wherein F is a setpoint frequency; C is the velocity of sound (normal temperature is 343 meter per seconds); L is the acoustic resonance length of tube; Select sound source then, design the diameter of acoustic resonance pipe according to the bore of sound source; Make the acoustic resonance pipe according to the design size of acoustic resonance length of tube and diameter again.
The present invention utilizes sound pipe resonance to obtain characteristic frequency (low frequency or infra-acoustic frequency), promptly uses the sound radiation ability that air resonance principle in the sound pipe encourages sound source infrasonic sound frequency range.Send the odd-multiple of 1/4 wavelength of sound wave if pipe range is a sound source, the energy of the sound wave of the openend radiation of sound pipe will strengthen manyfold by the acoustic energy than the direct radiation of sound source own because of inner air tube resonance so.
Below by the test characteristic of sound pipe resonance is verified:
Test 1: select for use internal diameter to do experiment for the round hard plastic tube of the long 3450mm of Ф 240mm.
The test cone loudspeaker of Ф 250mm bore, diaphragm diameter is about ф 230mm.Selecting internal diameter for use is Ф 240mm, and the round hard plastic tube of wall thickness 5mm is made sound pipe, pipe range 3450mm.
Below measure and all adopt Denmark B﹠amp; The PULSE3560B dynamic signal acquisition analytic system that k company produces is carried out.
Before the test, earlier loudspeaker being installed on an internal diameter is Ф 240mm, and length is that the circle of 260mm is closed in the case, as sound source for a short time.During test, will have the Ф 250mm loudspeaker that closes case and place anechoic room,, frequency response curve be measured by microphone at 1m place, distance loudspeaker the place ahead.Then, again the plastics sound pipe of Ф 240*3450 is installed on the place ahead of closing case for a short time, makes the loudspeaker radiation direction aim at sound pipe, during test, the sound pipe openend is placed in the anechoic room, microphone places on the axis apart from sound pipe 1m, by microphone frequency response curve is measured, referring to Fig. 4.
Two curves measuring more than the analysis can be seen pipe resonance, and the good results are evident.At resonance frequency 25Hz place, first rank, band sound pipe ratio has not improved 39dB with the sound pressure level of sound pipe; At resonance frequency 75Hz place, second rank, band sound pipe ratio has not improved 11dB with the sound pressure level of sound pipe, and at resonance frequency 124Hz place, the 3rd rank, band sound pipe ratio has not improved about 6dB or the like with the sound pressure level of sound pipe.And 25Hz here and 75Hz and 124Hz are the frequencies that corresponds respectively to 1/4 wavelength, 3/4 wavelength and 5/4 wavelength of the long acoustic resonance pipe of 3.45m.
Utilize resonant frequency equation: L=iC/4F below, obtain each order frequency in the above acoustic resonance pipe, wherein F is a frequency; C is the velocity of sound (normal temperature is 343 meter per seconds); L is the acoustic resonance length of tube; I is a node odd number 1,3,5
F1＝343/(3.45×4)＝24.85HZ
F2＝343/(3.45×4/3)＝74.56HZ
F3＝343/(3.45×4/5)＝124.3HZ
Or the like.
Test 2: close case with Ф 130mm loudspeaker and add Ф 130*2600mm sound pipe and do experiment.
The Ф 130mm loudspeaker diameter Ф 130mm that packs into, long in the cylinder of 400mm, back face closure is made one and is closed case for a short time.Behind the anechoic room build-in test, in loudspeaker radiating surface the place ahead a diameter Ф 130mm is installed again, the sound pipe of long 2600mm is measured in anechoic room and is obtained two frequency response curves, referring to Fig. 5.
Utilize resonant frequency equation: L=iC/4F below, obtain each order frequency in the above acoustic resonance pipe.
F1＝343/(2.6×4)＝33.0Hz.
F2＝343/(2.6×4/3)＝99.0Hz.
F3＝343/(2.6×4/5)＝164.9Hz.
F4＝343/(2.6×4/7)＝230.9Hz.
Or the like.
Each the harmonic peak frequency values that adds in each the rank resonant frequency value that more than calculates and the experiment on the frequency response curve of sound pipe test is basic identical.
Draw by above verification experimental verification: 1, along with the rising of frequency, the amplitude that the sound pressure level of sound pipe resonance rises can reduce.This is because along with the rising of frequency, its wavelength shortens gradually, and when wavelength of sound was suitable with the sound pipe diameter, the sound wave of non-sound pipe axis direction propagation significantly increased, and the vertical air column resonance in the sound pipe weakens, until resonance again.As the sound more than the 1000Hz, its wavelength is less than 0.34m, and is suitable with the pipe diameter of Ф 0.24m, so just there has not been the air column resonance phenomena in the frequency range more than 1000Hz.2, want to improve the frequency of sound pipe higher order resonances, must dwindle the diameter (promptly selecting small-bore loudspeaker) of sound pipe.Below the wave length of sound frequency suitable with the sound pipe diameter, air column can resonance in the sound pipe.3, in ultralow frequency range, during as sound pipe resonance, at lowest resonant frequency F1 point, the sound pressure level of measuring when adding sound pipe does not add the sound pressure level raising 20-30dB that sound pipe is measured than loudspeaker.
Can also draw by above verification experimental verification: obtain the sound pipe air resonance of ultralow frequency or infrasonic sound frequency range, must make the length of sound pipe equal 1/4 of sound pipe single order resonance frequency wavelength at least, and frequency be low more, wavelength is long more, and it is long more that sound pipe will be done.As the infrasonic wave of 10Hz, its wavelength is 34.3M, λ/4=8.58M.Doing one sound source of such length, is to build, transport, install all inconveniences.So when manufacturing and designing the acoustic resonance pipe, consider whether the length of sound pipe is convenient to the transportation installation, if sound pipe is long, can take to connect with right-angle bend, can shorten the entire length of sound source like this.But the length that must guarantee crooked position adds the length that connects short tube and equates with the total length of required sound pipe, and the diameter of crooked position and required sound pipe equal diameters.
Below respectively sound source is added straight tube and sound source by test and adds swan-neck and test, measuring sound source adopts the 130mm loudspeaker to close case, crooked sound pipe by 6 right-angle bends be connected short tube and form, (its mounting means is referring to Fig. 2,3) total length is 2400mm.
For fear of of the harmful effect of non-free found field, during test microphone is placed the open end place-centric of sound pipe to test result.With sinusoidal signal and octave band pink noise signal, respectively straight sound pipe and crooked sound pipe are measured.
Table 1 be the actual measurement straight tube and the bend pipe frequency response curve on each rank harmonic peak frequency values and harmonic peak sound pressure level value.
The straight sound pipe of table 1-1: sinusoidal signal test.
| Harmonic peak frequency (Hz) | 33.5 | 106 | 180 | 250 | 325 | 387 | 462 |
| Peak sound pressure level (dB) | 116 | 123 | 127 | 130 | 125 | 124 | 127 |
| Harmonic peak frequency (Hz) | 530 | 600 | 670 | 750 |
| Peak sound pressure level (dB) | 127 | 126 | 123 | 123 |
The crooked sound pipe of table 1-2: sinusoidal signal test.
| Harmonic peak frequency (Hz) | 35.5 | 115 | 190 | 265 | 345 | 412 | 475 |
| Peak sound pressure level (dB) | 116 | 124 | 129 | 131 | 126 | 128 | 130 |
| Harmonic peak frequency (Hz) | 545 | 630 | 710 | 775 |
| Peak sound pressure level (dB) | 127 | 127 | 121 | 124 |
Table 2 is with the straight tube of octave band pink noise measurement and the sound pressure level frequency response data of bend pipe:
Carry out same test by straight tube and swan-neck to same internal diameter, same length, what then both result is compared goes out: in subaudible scope, the sound pressure level of each square elbow decays in 1.4/6=0.24dB.So, in carrying out engineering design and construction, when the transmission infrasonic wave, can use folding bend pipe to replace straight tube fully, can dwindle the length dimension of acoustic resonance pipe like this, infra-acoustic frequency sound source product can be taken up space less, be convenient to store and transportation.
2., assembling sound source harmony resonatron
Sound source harmony resonatron is assembled into one, and wherein an end of acoustic resonance pipe is an openend, and the other end is connected with sound source.
Sound source adopts loudspeaker, before assembling, in order to prevent the loudspeaker sound wave interference sound wave of surface radiation forward of radiation from behind, loudspeaker is packed into close in the case for a short time earlier.It is fixedly connected that the radiating surface that loudspeaker will be housed is then aimed at an end of sound pipe, by the openend sounding of sound pipe.
3., design spheroid infrasonic wave acoustic cumulative chamber
Determine that at first setpoint frequency and spheroid major axis have following relational expression: F=C/2a * 6, obtain the design size of spheroid major axis then according to relational expression; Wherein F is a setpoint frequency; C is the velocity of sound; 2a is the major axis dimension of spheroid; Again according to two minor axis dimension of the size design spheroid of the sound source harmony resonatron that is assembled into one and measured object; Make spheroid infrasonic wave acoustic cumulative chamber according to the design size of spheroid major axis and two minor axises then;
Spheroid infrasonic wave acoustic cumulative chamber is the initial point of three-dimensional coordinate with the geometric center O of spheroid, and the x axle on the surface level is the major axis of spheroid; Y axle on the surface level is a minor axis of spheroid, be another minor axis of spheroid perpendicular to the axle of surface level, if two minor axises are equal, this spheroid is exactly a rotational ellipsoid.The size of spheroid infrasonic wave acoustic cumulative chamber can depend on the needs.
According to analysis to test figure, found sound source generation infrasonic wave rule in spheroid, be that setpoint frequency and spheroid major axis have following relational expression: F=C/2a * 6, above relational expression has been arranged, when design spheroid infrasonic wave acoustic cumulative chamber, just be easy to obtain the major axis dimension of ellipsoid according to the required setpoint frequency of test.
4., determine the position of indoor sound source focus of spheroid infrasonic wave acoustic cumulative and infrasonic wave sound field reference point
At first according to oval semicoke apart from formula:
Determine earlier the distance of the indoor sound source focus of spheroid infrasonic wave acoustic cumulative, determine the position of sound source focus and infrasonic wave sound field reference point then according to the distance between 2 o'clock to infrasonic wave sound field reference point.
In plane right-angle coordinate, oval standard equation is:
A wherein〉0, b〉0.The greater is that oval major semi-axis is long among a, the b, and the shorter one is long for minor semi-axis.
As a〉during b, focus on the x axle, focal length=2c,
For rotational ellipsoid, can find out two focuses on the spheroid major axis according to above formula, two focuses are symmetrically located at the both sides of spheroid geometric center O, and these two focuses are respectively sound source focus DO and infrasonic wave sound field reference point MO, as Fig. 1 institute not.
Utilize the sound pipe resonance characteristic,, determine the position of sound source focus and the position of infrasonic wave sound field reference point, can in spheroid, create territory, a high strength infrasonic wave acoustic place by indoor at spheroid infrasonic wave acoustic cumulative.
5., the sound source harmony resonatron and the measured object that fixedly are assembled into one
Place spheroid infrasonic wave acoustic cumulative indoor the sound source harmony resonatron and the measured object that are assembled into one, wherein the openend of acoustic resonance pipe places on the sound source focus, and measured object places reference point or centers in the infrasonic wave sound field cumulative zone of reference point;
It can be microphone or animals and plants that can experimentize for the researchist and various starting material etc. that sound source adopts loudspeaker, measured object.
6., connect the signal source of sound source after, the infrasonic wave that sound source produces at the ellipsoid internal radiation, forms cumulative infrasonic wave sound field by the air resonance in the acoustic resonance pipe in the right hemisphere space of spheroid.
Further set forth the present invention below in conjunction with embodiment
Sound source is selected Ф 130mm loudspeaker; Sound pipe length is 8060mm; The sound pipe diameter is Ф 130mm.
For prevent when anechoic room is measured loudspeaker backward radiation sound wave with interfere mutually to the sound wave of previous irradiation, need mask the sound wave of radiation backward.Therefore, Ф 130mm loudspeaker is packed into a diameter is Ф 130mm; Long in the fully sheathed case of 400mm, go out in order to the acoustic irradiation that prevents radiation backward.Be 8060mm with length then; Diameter is that an end of 130mm sound pipe is installed loudspeaker, and the other end of sound pipe is an openend radiation sound.
The loudspeaker and the sound pipe that are assembled into one are placed anechoic room, place apart from sound pipe the place ahead axis on 1m place with microphone this moment, with microphone is placed sound pipe openend center, the frequency response curve that records respectively with sinusoidal signal is shown in curve among Fig. 71 and curve 2.
Then the loudspeaker that is assembled into one and the openend of crooked sound pipe are placed in the spheroid infrasonic wave cumulative chamber, as shown in Figure 6, this spheroid is that a major axis is 1500mm, and two minor axises are respectively the rotational ellipsoid model of 1200mm.
The openend of crooked sound pipe is placed spheroid sound source focus DO place, microphone is placed infrasonic wave reference point MO place, use the measured frequency response curve of sinusoidal signal equally shown in the curve among Fig. 73.Three curves in the analysis chart 7 are as can be known:
The frequency response curve that sound pipe openend center records in anechoic room (curve 2), than the frequency response curve (curve 1) that records at 1M place, sound pipe radiating surface the place ahead, sound pressure level on average exceeds about 25-30dB.And in spheroid, sound source places left focus, and microphone places on the frequency response curve (curve 3) that the right focus place records, and the frequency range below 40Hz, sound pressure level are higher than the sound pressure level that the sound pipe opening part records in anechoic room (curve 2).This shows, major axis 1500mm, the rotational ellipsoid model of minor axis 1200mm can promote the sound pressure level of infrasonic sound frequency range.We can say that also this spheroid is tangible for the sound cumulative effect of infrasonic sound frequency range.
The frequency response curve of measuring with the octave band pink noise 1,2,3 as shown in Figure 8.
The frequency response curve that analysis-by-synthesis Fig. 7, Fig. 8 record respectively with two kinds of test signals is as can be known: in the following frequency range of 40Hz, the sound pressure level that records in spheroid is higher than the sound pressure level that the sound pipe open centre records.
Distribution of sound field to hemisphere that sound source is not installed in the spheroid (referring to offer the sound field zone that experiment is used) interior space each point is described further below.
If sound source is placed on the left focus in the spheroid (DO), if when measuring in the band limits that can focus on, the acoustic energy that sound source is sent just should focus on the right focus (MO) of spheroid preferably.The sound pressure level that shows the right focus place is the highest, and all the other each point sound pressure levels all are lower than the sound pressure level at right focus place.The difference of sound pressure level is big more, and focusing effect is good more.Otherwise, focus on bad.If the sound pressure level of each point is all identical in the right hemisphere space, be exactly not focus on fully.
By test with studies show that, when using small-sized ellipsoid model (major axis 1500mm minor axis 1200mm) test, when the test frequency (frequency band) that uses not simultaneously, right hemisphere space distribution of sound field also has nothing in common with each other in the spheroid:
Frequency range more than 500Hz, acoustic energy is good at right focus MO place focusing performance.And frequency is high more, and focusing performance is good more.Shown in the 1KHz among Figure 10.
In 40Hz-500Hz frequency range, along with the reduction of frequency, focusing performance worse and worse.Shown in the 63Hz among Figure 10.
Frequency range below 40Hz, out-focus almost completely in spheroid, and also it is nearly all the same to form the sound pressure level of each point in the spheroid.Shown in the 16Hz among Figure 10.
The measurement point synoptic diagram during distribution of sound field is as shown in Figure 9 in spheroid to measure each frequency (frequency band).
Figure 10 is the sign picture of typical octave band in each measurement point test result of spheroid right-hand part space.It is three typical octave bands of centre frequency that measurement has been chosen with 16Hz, 63Hz and 1KHz, and these three octave bands are represented a kind of situation that whether focuses on respectively
Among Fig. 9, DO is the left focus of spheroid, is place, sound source place.MO is the right focus of spheroid, place, microphone place.A among the figure, B, C, F, Q, E, G, H, R and 30,20,10 ,-10, points such as-20 all are the positions of measurement point.Distance between each adjacent measurement points all is 10cm.
Each measurement point is all being represented, by this perpendicular on the circumference of a circle on the plane of major axis have a few.The center of circle of this circle is the intersection point of plane and major axis, and this radius of a circle is this vertical range of putting major axis.
Each measurement point in Figure 10 is as marking the low 6dB of sound pressure level that " (6) " represent that the sound pressure level of this point is ordered than MO; Represent that as mark " ◎ " sound pressure level of this point equates with the sound pressure level that MO is ordered; The rest may be inferred.
Here should be noted that for the spheroid of different size, frequency characteristic has nothing in common with each other.The rotational ellipsoid that test is used is meant major axis 1500mm, the spheroid of minor axis 1200mm, and various test datas are all relevant with the characteristic of this spheroid with test curve.The size of spheroid is determining its characteristic.But the rotational ellipsoid of different size also has its common rule to follow, the relational expression that frequency that Here it is and spheroid major axis have: F1=c/2a * 6.
Frequency less than the frequency range of F1=c/2a * 6 in the complete out-focus of sound field in the spheroid.In the spheroid sound pressure level size of each measurement point all with MO order identical, sound field is evenly distributed.In this frequency range, the sound pressure level that records at the MO point is higher than the sound pressure level that aforementioned sound pipe open centre records.
This shows, use spheroid in the infrasonic sound frequency range and obtain, just must use the frequency range of f＜F1 than the taller sound pressure level in sound pipe open centre place.And must satisfy F1〉condition of 20Hz=c/12a.Promptly must satisfy the condition of a＜343/ (20*12)=1.43M.That is to say that the major axis dimension of employed spheroid should be not more than 2a=2.86M.
Check, if the major axis dimension of design spheroid is 4m, F1=c/2a * 6=343/24=14.3Hz. that is to say so, when major axis is the ellipsoid in-vivo measurement of 4m, frequency range below F=14.3Hz could realize that the sound-pressure-level measurement value in the spheroid is higher than the sound-pressure-level measurement value at aforementioned sound pipe open centre place.And be higher than the frequency range of F=14.3Hz (14.3Hz＜f＜F2, F2=c/a=171.5Hz) in, the sound-pressure-level measurement value in the spheroid is lower than the sound-pressure-level measurement value at aforementioned sound pipe open centre place.
From relational expression as can be seen, too little spheroid though F1 can rise, because of volume is too little, is done animal experiment or can not be held any more during to anthropogenic influence's test, and sound field also can be affected.But the size that increases spheroid is subjected to the restriction that F reduces again, so make when being applied to the spheroid of infrasonic wave frequency range, its size should be taken all factors into consideration.Certainly, the above frequency of F1 is not to use, but the gain of its sound pressure level is not as F1 big with lower frequency.
The above various tests of doing all are to use medium and small cone loudspeaker, and the sound pressure level data on the various curves that obtain in the test all obtain when feeding loudspeaker 1W electric power.If create the infra-acoustic frequency sound field of high sound intensity, also need to improve the radiation acoustical power of sound source, just to improve the electric power of the sound source of feeding: or the piston area that produces infrasonic sound source is increased, or the amplitude that makes piston motion increases (can use piston pump), or the assembly that does the infrasonic wave sound source increases the sound output of sound source.
In Fig. 7,, just can in the ellipsoid model of test usefulness, produce the frequency of 10Hz and the sound pressure level of 103dB with the electric power of 1W, the little loudspeaker of ф 130mm.If imagination adds to the electric power of sound source and is increased to 100W, be exactly the input electric power 20dB that risen, the acoustical power of calculating sound source output by theory also should improve 20dB, the sound pressure level that all measurement points record in MO point and the whole right hemisphere space in spheroid also should all improve 20dB, can reach 123dB.So just created the frequency of a 10Hz, the volume that can reach 123dB is the infrasonic wave sound field of half spheroid.
Certainly, can use the bigger loudspeaker of bore, can input to the higher electric power of sound source, make the acoustical power of sound source output bigger.Or use combination loudspeaker sound source.The loudspeaker of four same bores is installed in twos relatively, and the same-phase feed in order to strengthen the resonance dynamics of air in the sound pipe, increases the output acoustic power of sound pipe.Also can utilize the to-and-fro movement of large-area piston pump to replace cone loudspeaker, can improve the infrasonic intensity of output widely as the infrasonic wave sound source.
The acoustical power that increases sound source by above various approach is exported, and cooperates the method for the characteristic of sound cumulative in the spheroid again, can create out the stronger infrasonic wave sound field of high sound pressure level.Design the key techniques that is also noted that at acoustic resonance pipe and spheroid infrasonic wave cumulative chamber in addition:
1, the selection of acoustic resonance pipe and spheroid must be the material that material is hard, mass area ratio is big, sound insulation property is good.Pipe and spheroid inside surface are smooth.
2, for sound source and microphone (animal and plant or various starting material etc.) are installed, can open a door in spheroid, come in and go out and the equipment carrying, must guarantee that inside surface is consistent with spheroid, and effective sound insulation measure is arranged for personnel at the short-axis direction of spheroid.
Must keep the cleaning of institute's body, clean (no greasy dirt) when 3, selecting modulation institute stream loudspeaker for use, can consider in the spheroid short-axis direction institute hole that begins to rehearse as sound source.
Claims (1)
1. infrasonic wave acoustic energy aggregation method by ellipsoid body is characterized by and follows these steps to carry out:
1., design acoustic resonance pipe
At first calculate the length that formula: L=C/4F obtains the acoustic resonance pipe according to the pipe resonance frequency, wherein F is a setpoint frequency; C is the velocity of sound; L is the acoustic resonance length of tube; Select sound source then, design the diameter of acoustic resonance pipe according to the bore of sound source; Make the acoustic resonance pipe according to the design size of acoustic resonance length of tube and diameter again;
2., assembling sound source harmony resonatron
Sound source harmony resonatron is assembled into one, and wherein an end of acoustic resonance pipe is an openend, and the other end is connected with sound source;
3., design spheroid infrasonic wave acoustic cumulative chamber
Determine that at first setpoint frequency and spheroid major axis have following relational expression: F=C/2a * 6, obtain the design size of spheroid major axis then according to relational expression; Wherein F is a setpoint frequency; C is the velocity of sound; 2a is the major axis dimension of spheroid; Again according to two minor axis dimension of the size design spheroid of the sound source harmony resonatron that is assembled into one and measured object; Spheroid infrasonic wave acoustic cumulative chamber is the initial point of three-dimensional coordinate with the geometric center O of spheroid, and the x axle on the surface level is the major axis of spheroid; Y axle on the surface level is a minor axis of spheroid, be another minor axis of spheroid perpendicular to the axle of surface level, then according to the design size of spheroid major axis and two minor axises manufacturing spheroid infrasonic wave acoustic cumulative chamber;
4., determine the position of indoor sound source focus of spheroid infrasonic wave acoustic cumulative and infrasonic wave sound field reference point
At first according to oval semicoke apart from formula:
Determine earlier the indoor sound source focus of spheroid infrasonic wave acoustic cumulative to infrasonic wave sound field reference point apart from 2c, determine the position of sound source focus and infrasonic wave sound field reference point then according to the distance between 2 o'clock;
5., the sound source harmony resonatron and the measured object that fixedly are assembled into one
Place spheroid infrasonic wave acoustic cumulative indoor the sound source harmony resonatron and the measured object that are assembled into one, wherein the openend of acoustic resonance pipe places on the sound source focus, and measured object places in the infrasonic wave sound field cumulative zone of reference point or reference point;
6., connect the signal source of sound source after, the infrasonic wave that sound source produces at the ellipsoid internal radiation, forms cumulative infrasonic wave sound field by the air resonance in the acoustic resonance pipe in the right hemisphere space of spheroid.
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| EP0155028A1 (en) * | 1984-02-16 | 1985-09-18 | Dornier Medizintechnik Gmbh | An apparatus for the non-contact disintegration of concrements present in a body |
| US6527080B2 (en) * | 2000-12-02 | 2003-03-04 | Ford Global Technologies, Inc. | Passive system for speech enhancement |
| CN2676353Y (en) * | 2003-12-05 | 2005-02-02 | 戴露雯 | Ultrasonic focusing processing unit |
| CN101103392A (en) * | 2005-01-14 | 2008-01-09 | 英国国防部 | An acoustic reflector |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0155028A1 (en) * | 1984-02-16 | 1985-09-18 | Dornier Medizintechnik Gmbh | An apparatus for the non-contact disintegration of concrements present in a body |
| US6527080B2 (en) * | 2000-12-02 | 2003-03-04 | Ford Global Technologies, Inc. | Passive system for speech enhancement |
| CN2676353Y (en) * | 2003-12-05 | 2005-02-02 | 戴露雯 | Ultrasonic focusing processing unit |
| CN101103392A (en) * | 2005-01-14 | 2008-01-09 | 英国国防部 | An acoustic reflector |
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