JPS59500116A - sound equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] sound equipment The invention is configured to acoustically vibrate across the geometric extension of the chamber. Relating to sound attenuating devices of the type comprising a sheet metal member forming at least a part of a partition wall Ru.

It is possible to absorb sound up to a certain range, thereby correcting the acoustic condition of the room, and to reduce noise. The basic characteristics of an acoustic attenuation device are that it can attenuate the sound and isolate the sound source from the surroundings. That is.

Sound is created by the wave-like motion of a medium, and this wave-like motion is a function of the nature of the medium through which the sound travels. Propagates at a rate that depends on quality.

This medium can be gaseous, liquid or solid. Air at normal atmospheric pressure and a temperature of about 20°C In air, the speed of sound is approximately 344 m/s. However, this speed of sound propagates through solid objects. If internal damping is low, it will be faster, and if internal damping is high, it will be slower. Acoustic Energy - occurs as a disturbance within the medium, causing a mass point within the medium to move around the equilibrium position. make it vibrate. When the mass vibrates in the same direction as the sound wave propagates, the acoustic Energy appears as longitudinal waves. This can occur in the case of aerodynamic media. This is the only propagation method available. That is, acoustic energy flows through the medium in the same direction as the waves. solid In the case of physical media, complex waveforms are also generated. That is, the acoustic energy changes direction. Well, it flows perpendicular to the direction in which sound propagates. This wavelength corresponds to the direction of motion and phase within the medium. Determined by the minimum distance between mutually adjacent mass points in the same direction. The frequency of the wave is obtained from the relationship between the propagation velocity in the medium, the vibration interval and the frequency of vibrations per unit time. Ru. Sound is affected by obstacles placed in the propagation path. The area where the sound is affected is Determined by the specific frequency of the sound. Low frequency (long wave), table provided by disturbances If the area is small relative to the wavelength, the area over which the acoustics are affected is virtually negligible.

When the frequency is high (short wave) and the size of the obstacle surface is comparable to the wavelength, wave propagation is actually The target stops and the sound has to change direction. Obstacle surface totally reflects this frequency In this case, the direction of the sound is reversed towards the source. If sound can pass through the faulty surface, then the fault absorbs a certain amount of incoming acoustic energy that is absorbed or transmitted through it. However, the remaining acoustic energy is reflected back to the sound source. There are no equivalent obstacles in the sound wave propagation path. If this is not the case, so-called free sound propagation takes place.

Therefore, how a given acoustic device is positioned relative to the sound source in a given room. Along with the method, the quality and sound attenuation determined by the device is partly due to the sound waves from the sound source. A range of proportions of disturbances to the sound source, some of which are frequency-dependent propagation limitations, absorption, transmission, and is the distribution of quantity between the reflections. Preventing sound from being audibly radiated from the source In other words, by shielding, a certain degree of acoustic attenuation is obtained in the surrounding area.

On the other hand, the sound generated by the sound source is only reduced to a small extent or When the screen reflects sound back to the sound source at a frequency that is only slightly transmitted to the sound screen surface. The presence of the screen will audibly amplify the sound.

According to the above, the acoustic part of the sound source force 1 that is not absorbed by the screen is It will travel through the air until it reaches the compartment wall. This wall has total reflection In this case, the sound is directed towards the sound source and the room partition wall opposite the first mentioned wall, and the sound wave is directed towards the Depending on the shooting angle, it is also returned to other room partition walls. The surface of the room partition wall absorbs the kinetic energy of the sound wave. If it is in a fixed state when receiving energy, the speed at which the mass moves within the sound wave is given by the surface. At the distance obtained, it approaches zero and becomes zero at the surface. Mass motion within a sound wave If is sinusoidal, the mass point velocity has a maximum at a distance from the partition plane equal to -4/4 of the wavelength. becomes. On the other hand, if the surface is not fixed, i.e. a function of the energy of the incoming sound wave When said surface vibrates as Therefore, the position of the zero point is physically indeterminate. This is related to frequency.

If the room partition walls are acoustically attenuated, some incident acoustic energy will be absorbed and transmitted. Reach 9 reflected. The absorption characteristics of the wall can be determined by coating the wall surface with a suitable acoustic absorbing material. can be significantly increased by This allows the acoustics to reach the sound source and other room areas. It becomes υ0 without returning towards the screen surface.

No sound is re-reflected in any direction from a given surface at a given frequency In this case, 100% absorption is achieved. That is, if the physical area of the surface is 1 m2 , the absorption is also 1 m2. Therefore the average absorption for a chamber with a given surface area The measurement of can be defined as the relationship between the total chamber absorption and the surface area. Give In order to achieve the 100% absorption obtained in the room at the given frequency, the entire constant surface is must be covered with an absorbing material, which reduces the total acoustic energy to @4 i o O% Absorbed on the surface of the droplet. Achieves 100% absorption for a given frequency In a room that is acoustically treated to each will be halved. If the sound source is abruptly cut off, the sound will stop immediately. become. In other words, the reverberation time of the room becomes zero, but this is because reflected sound pressure is created within it. That's because you don't get it. Similarly, for a room that does not absorb all heat, the time it takes for the sound to stop The interval is infinite, and the reverberation time is infinite. In reality, the thicker the chamber, the greater the reverberation time. In order to obtain an acoustically acceptable environment, the difference between the total absorption of the room and its volume must be There should be a certain relationship between the reverberation time of the O room before acoustic treatment and the absorption By measuring the difference between the reverberation time obtained after adding the step, you can determine the average amount of absorption in the room. It is possible to determine whether the acoustic environment of the room is good for the volume and usage of the room. can. Optimal sound attenuation by absorption is achieved by increasing the reverberation time of the room for all frequencies of the sound. O can be considered to be obtained at the same time. The basic room acoustic condition is determined by a number of factors. Regarding the geometry and shape of the room The relationship between the properties, mechanical stability, and specific absorption of the various chamber compartment surfaces is How the spectrum moves indoors is extremely important.

5 1 Tawara Sho 59-50011 (i (3) Mainly sound that arrives directly from the sound source The relationship between the sound arriving from the surface of the room and the surface of the room is that the position where the sound is perceived is It depends on where it is inside. This recognition position directly identifies the source of the sound all over the world. If placed close together, the acoustics of the room will be unaffected or only negligibly affected. Not heard. As a result, the noise from the source may be reduced only slightly or not at all. It becomes. As the distance from the sound source increases, the reflected sound field becomes more dominant across the direct world. from absorbent materials placed adjacent to or on top of the compartment walls. The acoustic reduction is greatest adjacent to the wall. As will be understood, The walls and ceiling of the room are acoustically attenuated to reduce noise at the sound source location to any detectable range. It is impossible to attenuate. The advantage of absorption on walls is that the distance law It is to be effective. At the same time, it absorbs sound at a certain distance from the sound source. , the sound level is progressively halved faster (i.e., the shorter the distance from the sound source, the faster the sound level is halved). , the absorption at the wall will be higher].

The chamber itself constitutes an acoustic vibration circuit. If a sudden pressure change occurs in the room, the pressure in the room will The power level must change proportionately. Since the acoustic vibration circuit has inertia, , a certain amount of time elapses before a change in pressure level is made, and the change is due to the acoustic creation. The frequency response of the chamber, i.e., when the applied pressure changes are balanced and when the pressure changes When the change is repeated, i.e. the applied pressure increase is maintained for a given length of time. The natural resonant frequency of the room that appears in the step function that develops when it is cut off and then cut off. ・This situation is such that the acoustic vibration circuit is constantly exposed to the main constant atmospheric pressure. This means that it cannot fully adapt to rapid pressure changes in a straight line. increase the acoustic absorption of the room This makes it possible to attenuate the impact distortion generated from the acoustic room circuit to a certain extent. Wear.

Regarding absorption capacity, known devices for dealing with acoustic conditions are significantly frequency dependent. There are very many cases. The result is actually a sufficiently good acoustic condition and the instantaneous acoustic Attenuation can only rarely or never be achieved. Said frequency The desired linearity with respect to the reverberation time of the acoustically treated room cannot be achieved due to I don't get it. The low frequency range below approximately 250 Hz is acoustically particularly poorly attenuated. It will remain empty. This means that as the room gets larger, the problem of adjusting the reverberation time becomes more difficult. As the low-frequency waves in the noise waves caused by noise increase, the more troublesome the older sister becomes. It means to become. This means that some of the unabsorbed noise quictor is reflected on the reflecting surface of the room. This is because the acoustics will be further amplified. When using a known absorption device , the absorption decreases very rapidly at frequencies below 250 T (z), so this deficiency The points indicate the frequency range in which the above-mentioned room resonance exhibits an extremely high resonance amplification due to reflection inside the room. Appears only in the surrounding area. The acoustic amplification of the noise spectrum becomes strong at the main resonant frequency of the room. , this frequency decreases as the chamber becomes larger. In that case, significant acoustic energy energy is generated in the room structure in the form of mechanical vibrations, which further contributes to increasing the noise level. do. As is understood, these resonance phenomena can also lead to material destruction in the worst case. It also affects the architectural structure. As a result, low frequency noise can be reduced. Minimizing as much as possible is important primarily for presses, punching machines, and five-sided This is important in industrial sites that incorporate large machines such as rice machines and lathes. large Pressing or drilling a processed product increases pressure and gas, and this pulse is extremely It has extremely high energy and causes room resonance. Milling and rounding of large workpieces The work enhances the powerful acoustics that exhibit the complex strings. some energy Although energy disappears from these acoustic waves as a result of absorption, the spectrum The unabsorbed components of the torque are lowered in frequency and can cause unfortunate mechanical failure in the chamber structure. When combined with pulse-acoustic amplification to cause static sound pressure, it is gradually amplified as static sound pressure. .

People's reactions to noise are highly individualized. Individuals are particularly sensitive to groups with noise frequencies. Sensitive to alignment. In that case, some frequencies can be operated without causing any particular discomfort to the worker. may come directly from the equipment, but may also come directly from the acoustics that vary along the floor of the area. The alignment and phasing make it completely intolerable to other exposed individuals in the same location.

Frequencies in the higher noise spectrum - approximately 1000 T (z to 5000 Hz) − is not particularly high in terms of energy, but it produces permanent noise that can damage hearing, for example. Recent research has shown that low-frequency noise can cause sound damage. These movements can be extremely dangerous to humans and, as mentioned above, to building structures.

If the noise frequency is below about 125 Hz, fiber minerals, which are mostly used in practice today, Taking into account the fact that it is not possible to achieve any appreciable absorption with wool absorbent materials. If so, we also consider this fact that there are actually high-energy and harmful to humans and building structures. Compare this with the fact that the noise of If the A technical investigation of possible absorbent components would prove highly desirable. Of course , experiments with this purpose in mind have already been carried out, but the costs have not been resolved well. and technical issues have caused acoustic engineers to ignore the low frequency range.

As an example of a complex structure that is often extremely expensive and physically bulky, Helmholtz absorbers with a design of It is intended for a special function. (further) with known vibrating members and also with individual circumferential The main functions of those intended for use within the wavenumber range are briefly described below.

In its original design, the Helmholtz resonator consisted of a chamber with an opening leading to the surroundings. It consists of an air volume enclosed within. The opening is aligned with the interior of the chamber and has a given circumference. Resonates at the wave number. This type of absorber is suitable for e.g. Used to absorb individual frequencies, in principle 1 at Helmholtz resonance 00 efficiency. For example, the frequency in question is 25T(z), and it is This is the frequency that humans want to absorb, so the absorbing material is extremely large. It may take up a large amount of space. Naturally, a large amount of air has a relatively large mass, Significant shock inertia will therefore occur within the resonator.

The drastic pressure change inside the room caused by a powerful mechanical machine operating inside the room, such as a press, is , when the resonator is activated and the absorbed kinetic energy is released, it emits a powerful tone. scatter. If the absorption chamber is not mechanically stable, the resonator will have some resonant frequency It will release its acoustic energy into the lower frequencies of the frequency spectrum. The pulse is generated by a resonator that is vibrated by a single pulse. therefore increased and that loud noises arise from the absorbing material, which of course does not have the intended result. It can be. The inside of the resonator is made of porous material with appropriate sound damping properties, and is open to the surroundings. It is possible to improve the transient performance of the Helmholtz resonator by providing acoustic resistance in the aperture. However, this is done at the expense of the acoustic efficiency of the absorber.

Absorption at mid-low frequencies, i.e. 125 Hz to 1000 Hz, is more Helmholt resonator absorbers with smaller physical dimensions can be used to improve . This absorbent material takes the form of a hollow structure with a perforated cover plate attached to the studs. ing. This device is mounted on a compartment wall and is capable of transmitting high-frequency sounds within a given limited frequency range. It has acoustic efficiency.

These devices are often designed for frequencies where the volume is not excessive, so The acoustic properties of transient excitation of the resonator structure can be considered good in theory. . However, the cover ξ channel is often too flexible and does not cover the intended frequency range. It will vibrate in tune with a lower frequency. This is a structure that actually sounds transient. Unable to remain neutral to acoustic effects, the disturbance noise is caused by large Helmholtz resonator designs. It means that it occurs in the same way as in the case. Also, this cavity resonator crosses the interior and the hole. The sound can be reduced in both parts. Transient performance and absorption for this frequency range The linearity of the yield can therefore be improved, but also for such roles. Also, acoustic efficiency is sacrificed.

Another type of Helmhorn resonator is a vibrating panel mounted on a stud. It will be. A thin flexible gunnel made of non-perforated plywood is combined with an air chamber located at the rear. The maximum vibration is applied to the panel at the resonant frequency of this acoustic system.

Good absorption at this resonant frequency and negligibly small absorption at other frequencies. are the characteristics of such a vibrating panel. Assembles a homogeneous vibration diaphragm that vibrates on an air spring. As a result of the structural principle of Low resonant frequencies with fairly small volume parameters can be obtained. However, shaking The resistance damping of dynamic motion is small and approaches zero when the panel vibrates at the resonant frequency. . Additionally, this structure for improved low frequency absorption provides less sound attenuation for transient excitations. The disadvantage is that it causes significant instability with respect to vibrations, and significant inherent noise is expected. It must be. The structure is made of fiber material, and it is not possible to make it internally sound attenuating. However, in that case the efficiency of the structure decreases rapidly as the sound attenuation increases. becomes. The fiber material arranged at the rear makes the gunnel sound attenuating purely mechanically. Only occasionally can acceptable transient stability be obtained, and the fiber material becomes permeable due to contact action. prevent the flannel from vibrating. Obviously, in that case Gunel would It has stopped functioning.

The fiber absorbent material has a thickness of 50 to 100 cm and a thickness of 40 to 2/m3 to 70 to 97 cm. Most have a density between m3. Therefore, such an absorbent is e.g. 1.200x If built with a size of 600m+n, it can stand on its own. Fiber minerals - substitute for wool absorbent material A typical characteristic is that the acoustic propagation velocity in the material is approximately halved, or approximately 172r+1//s. It is to be done. Absorption can reach up to 100 coefficients, but the material remains constant It is not so dense that the sound is reflected off the surface at frequencies like . Absorbing material receives acoustic energy It functions by shorting the energy. A mass point carried within the sound wave passes through the fiber material. and only when the mass velocity is high within the conveying path section of the fiber structure. Absorption takes place.

A fibrous absorbent material having a thickness of 100 mm, the absorbent material being attached closely to the compartment wall. As an example of the absorption characteristics obtained when the lower absorption limit is approximately 45QH It is possible that it is in z. The absorber is separated from the surface force of the wall by 1 m and then If placed far apart, the limit frequency will be approximately 45 Hz. This calculation is based on the fact that the absorber absorbs sound waves. in a material without mechanical vibration and with a constant propagation velocity equal to 1.72 m/s. This is done on the assumption that -4/4 of the wavelength travel causes absorption on the order of 100. However, the truth In some cases, the material distributed within the absorber vibrates in synchrony with the sound waves. This is the material itself constitutes a denser medium than air, and therefore certain material parts are themselves isotropic. This results in wave-like motion in both directions.

This physical fact is that an absorbing material gradually loses its absorption capacity as the frequency decreases. This means that when a constant sound pressure is maintained and the frequency decreases, the amplitude of the sound changes. This is because it increases. Entrained vibrations within the material also cause the surface and body of the absorber to stop resting. The acoustic energy is radiated in conjunction with the absorbing material contained in the material. The radiated sound waves are In this case, the sound comes from a mechanical surface that vibrates in an uncontrolled manner, so the sound is so-called unintentional sound. obtain the properties of

Therefore, these defective features should not be taken into account when considering acoustic devices containing fiber absorbing materials. There must be. These devices generate high frequencies with small vibration amplitudes, i.e. it works very well within the frequency range from about 1000 Hz, but falls, and therefore loses absorption capacity when the amplitude becomes higher. The hidden radiation of random sounds is already It is significant enough at mid-low frequencies. That's because this acoustic disturbance is not 125 Hz. between individuals because it typically affects intelligibility at the 650 Hz speech frequency. This is because normal conversation is inhibited in such an environment.

The transient reaction that occurs when the fiber absorbent material outlined above is subjected to strong and rapid changes in pressure is similar. If this is considered, the acoustic error will be even larger. In this case, each individual absorbent material is It is made to vibrate near its natural resonant frequency, but the frequency is very low, e.g. Since it is as low as 5Hz to 40Hz, it is noticeable along with the random noise generated. Disturbing low frequency situations may also occur within acoustically light environments.

The purpose of this invention is to provide a new, novel and improved acoustic device for sound attenuation, which can be achieved by using conventional sound absorbing materials. The object of the present invention is to provide a device which at least substantially eliminates the above-mentioned drawbacks. Ru.

For this purpose, the invention proposes an acoustic device of the kind mentioned in the introduction. but the device also includes the member being substantially swingable and the chamber being at least substantially acoustically closed, and the device is proportional to the change in displacement velocity of said member. means for damping displacement of said member across said geometrical extension. It is characterized by the combination of and. The characteristics proposed by this invention, the result of the combination of characteristics As a result, this acoustic device achieves high efficiency and is particularly extended toward low frequencies. Within a wide frequency range, the impedance to the received acoustic energy improves They will fit together. The device also improves dynamic capabilities with its transient excitation. However, this means that the acoustic emissions originating from the natural vibrations of the surface of this device are significantly reduced. This is because the transient reaction is therefore optimized.

The thin plate material may be an air permeable plate or an airtight plate, and may be rigid on either a flat or curved surface. In that case, said plate is elastically attached at its edges and is attached to the rear of said means. is made to vibrate in the aforementioned manner in conjunction with the volume of air filling the chamber in which it is placed. ing. According to a particularly preferred embodiment of the invention, the member is however relatively thin; consisting of a substantially planar porous fiber or perforated plate, the plate defining its edges; An air-filled cavity placed at the rear that is virtually fixed to avoid vibrations an air-filled space that co-moves during vibration with the air spring formed between the space and forms the air spring; Since the volume of is selected in relation to the density of said member, its mass and its flow resistance, The vibration of said member is maximum at the resonant frequency of this device, said maximum frequency being said It appears in the central region of the part and is damped by the flow resistance.

This method results in significant sound absorption within the component itself, and additional interference sound absorption (i.e. The sound absorption obtained through the surface impedance) connects the member to the vibration circuit of this device. It can be obtained by incorporating.

To obtain a desired constant effect, for example, the sound reduction of a member must be substantially symmetrical about its center. In order to ensure that the said member is substantially symmetrically arranged with one or more areas that allow more air to pass through than the rest of the member. can be done. In this respect, said areas are arranged, for example, in the direction of vibration of said member. Since it is surrounded by a tubular part, the area is sharply delimited and the length of the tube It has a volume/grammeter that allows the amount to be determined easily and precisely by changing the More flexibility regarding the resistive components of the area can be provided. This latter The device allows precise reproducibility and tubes with inherent or feed resistance are Vibration control means may be constructed, and when this means is inserted at the center point of the member , constitutes a dynamic valve that vents a specially effective chamber to the surroundings at the most sensitive point of the oscillating circuit. do. In order to control the vibration damping of the member, this device can alternatively or additionally at least one opening, said opening connecting a volume surrounded by the chamber and a volume surrounding said device; The amplitude of the vibratory motion of said member at the resonant frequency of this device is significantly reduced. It has a certain amount of internal flow resistance that weakens it.

According to another feature of the invention, the device includes at least one acoustic aperture. and the opening provides a connection between the volume enclosed by the chamber and the volume surrounding the device. substantially acoustically near the resonant frequency of the circuit formed by the aperture and the surrounding volume. , loading said member in a manner that substantially inductively increases the acoustic efficiency of the device. . Suitably, the aperture also resists and reduces acoustic coupling between the aperture and the member. It can show decreasing resistance.

This device in order to change the degree of damping in the room and form a flow-resistant screen in it may also exhibit significant flow resistance between the member and the opposing chamber compartment wall. At least one acoustic resistance element can be advantageously arranged.

In the device according to the present invention, the chamber partition wall disposed opposite to the member is a rigid plate. Or it can include the wall on which this device is mounted. However, if it is placed opposite the member, A special case is made when the compartment wall to be constructed consists of substantially the same material as the first described material. However, the efficiency of this device per unit area of installation is opposite to each other. can be more than doubled as a result of the joint action of the members that in the air volume enclosed between the members in the vibration circuit formed by the member and the air volume. more interconnected. This synergistic effect occurs at frequencies where the specific acoustic absorption of the materials used is high. Especially emphasized in the wavenumber range. The device according to the invention is characterized by the fact that the acoustic incidence angle and the sound source are has a certain characteristic sensitivity to distance. This sensitivity is The room compartment side has an opening of considerable size in relation to the area of the member. In case of Acoustic resistance in order to generate a sound pressure directed against the arriving sound pressure at the aperture exit. Contains.

The invention will now be described in detail with reference to a number of embodiments illustrated in the accompanying drawings. The features and advantages will then become clear.

FIG. 1 is a cross-sectional view of a first embodiment of the device according to the invention.

FIG. 2 shows a corner view of the device according to the invention.

FIG. 3 is a corner sectional view of FIG. 2, showing the upper half of the device according to the invention.

Figures 4 and 5 are a sectional view and a plan view, respectively, of a first variant of the device shown in Figure 1; be.

6 and 7 are respectively a sectional view and a plan view of a second variant of the device shown in FIG. There is an O FIG. 8 is a cross-sectional view of another embodiment of the device according to the invention.

9 and 10 are respectively an enlarged cross-sectional view of the upper opening of the device shown in FIG. FIG.

11 and 12 are enlarged cross-sectional views of the lower opening of the device shown in FIG. 8, respectively. and a side view.

13 and 14 show yet another embodiment of the device according to the invention, which A plan view and a cross-sectional view taken along line XIV-XIV are shown, respectively.

Figure 15 shows an acoustic frequency spectrum with a geometric mean frequency of 360 Hz. theoretically prevails at a constant sound pressure level between the acoustic amplitude level and the acceleration level FIG.

FIG. 16 1d Theoretical relationship of the device according to the invention with a device resonance frequency of 50 Hz It is a diagram showing a number/grammeter.

All identical or substantially identical components shown in the figures are designated by the same reference numerals. Ru.

FIG. 1 shows the main design of a device 10 according to the invention.

This device includes a judge consisting of walls 11, 12, 13, which is divided into three parts. separated and joined and hermetically sealed by mechanical sealing means. The judge tri Is it a plastic or aluminum part with a thickness of 1 to 3 mm? It has a suitable structure consisting of: a mechanically rigid structure; Ji Although the sides of the judge can absorb some acoustic energy, the It is members 14 and 15 that actually constitute the absorption area. These divisions are for this device. Various forms are provided depending on the intended use and principles of the invention. Therefore, the member 14 can take the form of a motive element, thereby transversely transversely extending the geometric extension of said member. The member 15 is vibrated acoustically in the cutting direction, while the member 15 has a rigidity that is greater than the force 1. density, in which case member 14 becomes the predominant absorbing surface, facing the sound source. The member 15 forms the rear wall of the vibrating member 14 and does not vibrate substantially. this The structure of the design can be called a single absorber and obtains absorption properties that allow angular absorption. However, the angular absorption is substantially hemispherical, and substantially affects the sound incident on the member 14. It's just a matter of being proactive. This type of invention allows the device to be attached directly to the partition wall. installed or in applications where the absorption effect should be directed to a fixed sound source. It can be used to advantage, but at the same time shields the sound of the sound source towards the surroundings. The purpose is to

Typical examples of such applications are the incorporation of discrete sound sources e.g. noisy machinery and acoustic isolation. It is. In that case, the device consists of a vibrating member 14 and a (passive) member (less active). vibrating member] 15, and the vibrating member 14 can be made of, for example, 20 A machine attached to a core of glass fiber with a thickness of 40mm and a density of about 209/m3 at least one of the peripherally facing surfaces of the member 1 is provided with a layer of physically stable steno fibers 5 is made substantially heavier and more rigid than the vibrating member 14, e.g. It has a density of IQOKg/m3.

The resonant frequency of this device 10 is determined by internal damping and by the inside of member 15 and the judge. Insert fiber absorbent material into both or one of the sides 11, 12, and 1.3. You can change it by entering. When this device is performing its function, the vibrating member 14I''i Displacement occurs due to sound pressure change, but as a result / palm and member 14, 1 ．． A pressure change occurs within the chamber 16 surrounded by 5. This pressure change causes the vibration member 14 to operate. The internal air is pressurized or depressurized depending on the direction of movement. Therefore, the mechanical circuit The balance condition is disturbed and therefore the differential part of the internal pressure change causes members 14, 15 to remain constant. amount can pass through. When this happens, the oscillatory motion constitutes additional flow resistance and friction. damped throughout the section, the movement is always determined by the dynamic impact of pressure changes. Give If the resulting pressure change occurs over a period of time, then the fraction of the resulting volume displacement passes through members 14 and 15 at a speed determined by the static flow resistance and its dynamic consequences. have to pass. The acoustic circuit formed by the device 10 is slow to balance during rest. If the velocity changes, the static flow resistance of the circuit as a whole will be approached.

The static flow resistance per unit area is much higher in the vibrating member 14 than in the (passive) member 15. If the vibrating member 14 is displaced very slowly, i.e. approximately 20:100, When displaced at a relative ratio, the flow resistance of member 15 is such that air cannot pass through vibrating member 14. It can be considered that it is short-circuited and does not substantially allow air to pass through. Table of both parts The surface is air impermeable, i.e. the flow resistance is reduced by e.g. a plastic coating on said surface. When short-circuited through the membrane, there is no significant difference in the displacement rate between members 14 and 15. Therefore, there is a significant pressure difference between the outer pick 7770 surface on the vibrating member J4 and the chamber. will not occur between the internal volumes of . Furthermore, very slow pressure changes (low frequency However, it is no longer possible to absorb sound, and it is possible to pick up changes in sound pressure and It cannot be converted into mechanical wasteful work.

The pressure change on the receiving surface of the vibrating member 4 approaches zero, and the arriving sound wave is equal to that of an ordinary fixed section surface. reflected in the same way. Period when flow resistance provides limited equalization of pressure The fastening member 15, which has a higher resistance to flow due to This residual pressure absorbs passively (in a less active sense) The change in retention pressure is applied through the displacement of the vibrating member]4, but the given resistance damping position A change in position can be caused on the surface of the vibrating member 14, where the amplitude of the arriving pressure wave is It is picked up by the moving member 14 and transmitted to the indoor air, distributing energy at a high density and large amount. The air transfers energy to a passive member 15 whose weight is substantially fixed; The latter element 15 converts the residual energy into heat. Therefore, the significant amount of absorption This is obtained by very slow acceleration of the moving member 14, which means that the acoustic energy is exactly zero H. This means that up to 2 are absorbed.

The acceleration of the vibrating member 14 increases and the static flow resistance increases as a function of the velocity of motion and the volumetric displacement. A value is reached that yields an exponentially increasing dynamic component, which component increases with the thickness of said member. If the flow exceeds the range of linear flow in the configured passage, the flow is gradual. , and virtually stops when the dynamic component approaches infinity. In member 15 Said limit value is at the same time exceeded much earlier, so that in this functional state the device Consider that the acoustic vibration circuit formed by 10 is completely closed to the flow through the surface. Can be done. Pinoquanoso and conversion of the applied acoustic energy is determined by each frequency and impulse. The case of time is carried out as a function of the acoustic impedance prevailing in the oscillating circuit, and therefore The resulting acoustic system is automatically balanced over the entire vibration range and has variable effectiveness. Includes resistive damping. This method is suitable for low frequencies and mainly for high frequencies within the expanded functional range. A fast-responsive absorption system is obtained that exhibits shock attenuation and high acoustic efficiency. Therefore, this system is the arrival sound Creates an acoustic absorption impedance that is balanced against acoustic waves and absorbs small amounts of disturbing acoustic energy. This is because its vibration function is well damped.

A wide vibration area can be selected in relation to the enclosed volume within the structure according to the invention, so that Resonant frequencies are already obtained with physically relatively small absorption devices. 0.5m2 A structure with a vibration area of Must have effective absorption close to 100% at the resonant frequency. Can be done. A device of the above design may, for example, have an external space of approximately 1150 x 550 x 200 Due to the dimensions, a pronounced insertion effect is obtained on the defined mounting surface, which is not possible with the known technology. It is something that cannot be obtained. The resulting acoustic absorption obtained in the device 10 is due to the vibrating member itself. the surface of member 14 within an absorption range that is greater than that available in the body and just above the resonant frequency. approximately twice as high as the upper limit frequency determined by the property, i.e. 400 It can go as high as 0 Hz.

This means that the device 10 has a substantially balanced acoustic impedance across its frequencies. Due to the fact that it acts as a non-realistic (reactive) The energy component in a sound wave that contains energy absorbs only actual acoustic energy. reflected from the surface of the vibrating member 14, as is the case with traditional fiber absorbent materials that can Instead, it is absorbed by the device 10.

” As an alternative to a dual device, the device member 15 shown in FIG. It can be a non-absorbing partition wall, such as an existing partition wall or wall of the space. this In this case, the members 15 are provided with suitable fiber absorbing material free from the vibrating member 14, Avoiding discrete reflections of wall forces and ensuring sufficient internal attenuation within the chamber 16, as described above. It is necessary to ensure that low-frequency sound is absorbed by partition walls as well. This device is When mounted on an abutting wall, a number of vibrating members 14 may have a common suction for several such members. They can be placed directly adjacent to each other in a direction across the containment room.

This device can also be designed in a so-called differential manner.

That is, it can be designed with two co-operative vibrating members of substantially the same structure. use vibrating members shall have substantially equal mechanical resonant frequencies and equal flow resistances. Therefore, they will cause a differential effect between them.

In doing so, they are subjected to an applied force that is related to their mutually defined vibration velocity, amplitude and direction of motion. The subtraction will dampen mutual vibrations. There, both members are substantially equivalent. A particularly effective dynamic damping is obtained in addition to the absorption properties. Therefore, parts 14.15 When used individually, the total absorption obtained is further increased; this increase is due to the individual components], 4. , 15 can be twice to four times as large.

When the ratio of the area of the vibrating member 14 to the volume surrounded by the chamber 16 is constant, the acoustics of the differential system The resonant frequency is approximately halved compared to an equivalent single system according to the invention. This differential system As a result of significantly improved efficiency, previously unknown insertion effects on specified mounting surfaces have been Obtained over an extremely wide frequency range. Room reduction for transient acoustic effects The attenuation values are particularly high when compared to using known techniques. It will be done.

The device according to FIG. 1 is also suspended at the edge of the compartment in the zoyana via elastic attachment means. It is possible to have two vibrating members 14, 15 or one of them. For example, about 2 approximately 10 to 5 mm of substantially planar selectively rigid fibrous material having a thickness of 0 mm. The cell-like comb is fixed in a frame with a width of 0 fields, and the frame is airtightly attached to the judge. When installing thin, virtually inflexible plastic or sheet metal members An advantageously used alternative attachment variant may consist of a thin neograin rubber frame. , the frame is stretched appropriately in the plane of the member, and the frame extends across the member up to the judge. When attached to an extension, a certain amount of tension is applied between the vibrating member and the 7-pole. . The tightening of said edge suspension means and an extension of said means in said plane then , can be tuned to determine the mechanical resonant frequency of the rigid members within the device 10. Ru. The rubber frame is about 10 to 50 songs wide and about 0.5 mm to 2 mm thick. You can choose.

the mechanical mass of the vibrating members 14 or 15 and when they are clamped to said frame; Lateral tension is the resonant frequency at which the member vibrates piston-like within the judge of the device 10. Determine the number. If a volume of air is coupled to said member, as a function of said member The acoustic resonant frequency at which the vibrational displacement of the surface of is maximized is obtained.

If none of the vibrating members include a flow resistance connecting the interior volume to the periphery, the device 10 is provided with one of the other defining means which provides a damping effect on the vibrations of the member. surrounded If you want to adjust the attenuation in the acoustic chamber 16 to give a given attenuation effect, or is the resonant frequency of this device, which changes the volume reduction in a given range, etc. , synthetic absorption characteristics or acoustic changes of the absorber in the case of serial production of equivalent devices. If you want to control vibration, insert an absorption plate member between the opposing surfaces of the main vibration member 14 and the can do.

When using vibrating members with low absorption and inherent damping, in order to obtain a wide absorption range, It may be necessary to apply this method. The suction of the vibrating member 14 with such a design is The absorbing capacity will decrease towards higher frequencies, therefore an absorbing partition wall in the chamber 16 is required. Inclusion means that the absorbed acoustic energy is transferred to the surface of the partition wall and that to be absorbed into. This partition wall can contain transparent openings or slots. The opening is made of aluminum or plastic, and the opening controls the air flow inside the device 10. A suitable design of the judge, including the tick part, is shown and follows the principles described with respect to Figure 1. Shows a corner of the device that is more functional.

FIG. 3 is a cross-sectional view of the corner of FIG. has an outer layer 18 of plastic membrane adhered thereto. Figure 3 shows two opposing vibration parts. differential structure with one vibration absorbing member and one substantially passive absorber It shows half of the structure with the members. Placed around edge 19 at the bottom of FIG. The part that is attached to the wall is designed to be easily attached to the wall soil, but in that case it must not be removed. When passive absorbers (less active absorbers) are used, the wall It can itself carry the absorbent material. The fibers shown at the top of Figure 3 are clearly visible. The absorbing member (vibration member) 14 is arranged on the aluminum or silastic part It is fixed to the fork-shaped absorbent member holder 20 and is appropriately fixed so that it does not move. Continuous rubber applied to the edges of the absorbent member 14 adjacent to the forked surface of the section It is sealed by a rope 21. This mounting method avoids edge vibration of the absorbing member 14 and This is an important method for achieving a tight seal, and furthermore, the absorbing member 14 is exposed to acoustic energy. Excited, responds to oscillatory motion in a linear manner, without unnecessarily altering the edge tension in the absorbing surface, It is also important to prevent the generation of mechanical secondary sound due to the absorption member and joint fluctuation. It is. Apply the fiber absorbent member 14 to the edge of the shampoo in the air-tight manner described above. By fixing, the vibration amplitude at the joint can be reduced to zero to the extent possible. Therefore, the vibration energy is concentrated on the actual absorbing material, and the jack It cannot be applied to the di-structure. The fiber absorbing member 14 also allows the judge to relax. It is installed in a flat state before being glued to the judge. Seen on the left side of Figure 3 As such, the part 22 placed on the wall 11 of the judge is made of fiber absorbent glued to said wall. a member, the absorbing member reducing internal reflections in chamber 16 and absorbing attenuation within said chamber. contributes to this and reduces undesirable vibrations within the judge. A device in which the absorbing member 14 faces the sound source. Vibrating members are used as absorbing surfaces in 14 then constitutes an excellent means of damping resonance phenomena and the formation of persistent waves within the chamber 16. Therefore, the judge may not be attenuated. The corner joints shown in Figure 2 are airtight. To secure the joint and avoid mechanical displacement of the otherwise stable shaft. It needs to be done in such a way that it

The center beam 23 of the judge section 24 in FIG. 3 mechanically stabilizes the section against vibrations. It is an attempt to do so. This device as a whole does not allow the judges to unreasonably vibrate. If the Very strong associated noise can be generated from the absorbing member at individual frequencies. same For this reason, this device cannot be installed against suspended structures made of aluminum parts, for example. and isolate the judge of this device somewhat from vibration effects and apply it to said part. , with a thin layer of plastic or rubber material on the supporting parts or mounting edges of this device. It is necessary to set it up and do it. From an acoustic standpoint, this device is designed so that the sound-absorbing surface is perpendicular to the sound source. It must be installed so that it faces the other side. The differential type device is correspondingly, but between the device 10 It is necessary to install with an air gap so that the sound acts on both parts 14 and 15. There is. In that case, the air gap can be, for example, 50 cavities wide. Spect The most evenly distributed sound absorption in the system is generally obtained with differential equipment; In that case, each alternative surface device is left free so that 5 of the mounting surfaces If only 0φ is used, reference numerals 25 and 26 are for binding and bonding glued into grooves within the part. Each hardened linkage element is shown.

Dynamically active valve means 27 are shown in FIGS. 4 and 5; vibratory member 14 according to the invention, or optionally incorporated into a substantially passive member. It is intended that the The valve means 27 has acoustic resistance and/or flow resistance. , a resistive component designated 28 is placed at the mouth of the tubular portion 29; In that case, the resistance is made to act within the surface of the vibrating member 14 in the direction toward the sound source. It is necessary to Furthermore, the valve means 27 is mounted at the geometric center point of the vibrating member J4. It is necessary, however, that damping of said member achieved through valve means is most effective. , and they act symmetrically. The dimensions of the valve means 270 are relative to the circumference of the acoustic circuit. whether any other connections have been made and whether the vibrating member or each vibrating member is fully or is determined by the density, thickness and area of said member. Determined by whether or not flow resistance is incorporated. The tubular part 29 is a vibrating member 14 vibration directions, so vibrations can be obtained within the viscous flow friction of this device. This friction increases with the length of the tubular part 29. Therefore, the valve means 27 is For example, it is possible to have a small space with a total opening area of about 5 m2 to 20 crn2, and for example , a quantitative parameter larger by about a power of 10 (50 m3 to 200 crn3) , thus effecting a substantially viscous damping of the vibrating member 14. This viscosity For damping, for example, a metal mesh with a size of 100 meshes to 400 meshes is used. or, for example, a stable fiber with a density of 50 g/m2 or a thickness of 0.3 van. A thin fine mesh network 30 of a layer of fibers is stretched over the open area facing the surroundings to create a pure Friction/grammeter components can be added that resist and increase damping. . It is important that this mesh 30 is not allowed to vibrate. For example, glass fiber is actually can be mounted within tube 29 so as to provide additional frictional damping. .

As can be seen, the flow resistance should not be so great as to render the valve means 27 ineffective. No.

6 and 7 show that porous or fibrous passive or vibrating members 14 are used. 2 shows a dynamically active valve means suitable for use in applications where For example, this member is 2 It can have a density as low as 0 to 97m3 and a thickness of 20cm, It therefore becomes desirable to vary the total flow resistance calculated across the vibrating surface. Sometimes. This means that one surface of said member, preferably the surface that bounds the chamber 16, Can it be covered with a thin elastic material that does not allow air to pass through, such as a plastic film 32? Alternatively, both sides of the member can be coated with the material. vibration 4 and 5 by opening the central region 31 of member 14 and allowing flow thereto. A similar function to the device shown in the figure is obtained, whereby the flow of the fiber vibrating member 14 used is A concentration of resistive properties is provided, causing a damping effect in the center of the member.

The openings 31 arranged in a layer or coating 32, for example in the form of a plastic membrane, are Somewhat larger than the area used in the apparatus shown in Figures 4 and 5, e.g. It can be made from m2 to 100 cm2.

The transverse cross-sectional view in FIG. These coatings may be, for example, homogeneous membranes of stable fiber structure or or a relatively dense fiber structure, with the fiber core 33 having a low density and If it has poor inherent stability in the plane, it is not effective to stiffen the fiber core 33. be. The surface layer 1.8, 32 is effective in damping the vibrations of the core 33, thereby This ensures that the surface of the vibrating member 14 breaks down into random vibrations. for example By selecting the surface layer 18 of the stable fibers that is bonded to the core 33, high frequency absorption can be achieved. will also improve. This becomes stable when the wavelength of the incident sound approaches the thickness of layer 18. This is because the fiber layer 18 is mechanically removed from the core 33. Core 33 has a thickness of 20 strips If the staple fiber layer 18 has a thickness of 0.3 ran, then this frequency As a number of wavelengths, the maximum possible vibrational absorption is obtained: Theoretically, there are 9 in the mind 33. kHz, layer 18 has a value of 575 kHz, and the zero mass on layer 18 and core 33 has that value. Both are valid, and the propagation speed in the material is calculated to be half the speed of sound in air.

The reaction times of this theoretical circuit are 0.12 m5 and 175 μS, respectively. The mass is already In the case of knowledge, it is possible to determine the reaction time actually obtained, and this reaction time is becomes longer as the value increases. Absorption is a function of the inertia of the mass within the surface attacked by the sound wave It is thought that this occurs as follows.

Let S be the surface on which sound pressure acts, and use the formula a = Pa-3/M to calculate the field of mass M on the surface. In this case, the acceleration caused by the sound pressure Pa (N/m2) prevents the surface incorporating the mass from following a linear If this amount of inertia is not large enough to cause absorption, absorption will occur. large mass Absorption decreases as the amount increases. The absorbing surface of the vibrating member 14 according to the invention covers the volume of the chamber 16. The machine is optimally loaded acoustically as a function of the air splash formed by the The mass inertia of a mechanical circuit is lower with acoustically excited vibrations than without an air spring. It will be small. The acoustic circuit also includes dynamic flow resistance and static flow resistance. In this case, the mass of the vibrating member 14 is effectively changed dynamically, so that the vibrational motion is significantly reduced. A linearization is obtained as a function of the dynamic damping of the member. The vibration member 14 reduces the flow resistance If so, it is applied mechanically directly to the vibrating member 14, or an acoustic circuit is placed around the This communication acts indirectly on the vibrating member due to the fact that this communication occurs between the surroundings and the air chamber 16. It is formed in such a way that a pressure difference causes a change in viscous resistance. Acoustic Gurus, i.e. short-term The rapid pressure change causes the vibrating member 14 to displace, thereby increasing the pressure inside the device. Make the level change. This displacement movement is damped with the device according to the invention and The start and stop times of a positioned vibrating mass are varied, and the mass is later The energizing force is started and braked more rapidly than when it ceases to act on the vibrating member. This issue The absorption capacity of the device due to brightness is then again dependent on both static and transient acoustic energy. have a positive impact on The dynamic damping provided by this device depends on the displacement change rate and displacement amplitude. therefore, the attenuation value is automatically adjusted within the acoustic circuit and always reaches the optimum value immediately. i.e. approaches a value approaching critical damping. The damping effect is maximum at the acoustic resonance frequency of this device. However, this resonant frequency is determined by the resonant frequency of the mechanical circuit, the area, and the volume used. as a function of the resistive damping factor and also the applied resistance damping. Mechanical part of the vibration circuit 14.15 is completely damped by the contact material that short-circuits the vibration of the vibrating member 14. , the acoustic circuit ceases to act as a resonant circuit and the acoustic absorption is therefore lower. The value decreases towards higher frequencies. Therefore, one mechanical vibration circuit is substantially free to oscillate. It has the form of a circuit and applies direct contact damping material to the vibrating parts of this device to achieve dynamic stability. If it is necessary to obtain a high quality is important. If a fiber vibrating member is selected that opens to the flow, the flow resistance must be sufficiently It is important to ensure that the temperature is high. In this way, the device has a pronounced acoustic resonance frequency. For a given wave number, the vibration amplitude is maximum at a constant applied excitation force. That is, this The acoustic impedance of the device is the minimum. If the flow resistance is insufficient, the circuit will be positive. The acoustic efficiency will decrease towards lower frequencies.

FIG. 8 shows a modification 10a of the principle diagram shown in FIG. 10th o and or 11th. The slots or gaps shown in Figure 12 are particularly suitable for Figures 4 and 5. or when the device shown in FIGS. 6 and 7 is not used, or when the vibrating member 14 or This device is used when the vibrating members 14 and 15 consist of means that are not in equal flow communication with the surroundings. Can be used to change the damping state and total flow resistance.

Figures 9 and 10 show the openings or Slots 34 are shown. In this case, the flow resistance 35 shown should be small and the area of the slot is the vibrating member 14. , 15 is substantially inductively loaded. However, this means that the large area of the groove acoustically transforms the interior chamber 16 into a small controlled area. , thereby providing substantially viscous vibration damping, and the device 10 so as to substantially stop acoustic 1 closing within the frequency range in which a is intended to operate. To a certain extent, the area of the slot 34 prevents the chamber pressure function from being shorted out. Ru. Significant viscous vibration damping expands the area of the opening 34 in the flow direction, thereby reducing the Forms an air tunnel and has a rectangular shape in the slot 34 with a ratio of the short side to the long side of 8 or more. It can be obtained by giving the shape of The substantially open slot 34 is Typical Helm Hole for Judges without adding mechanical flow resistance to the mouth or tunnel. A resonator opening is formed, and the operating frequency of the vaginal opening is the resonance of the vibrating member 14 in free air. It is necessary to adapt to the frequency, and the vaginal opening is calculated by the following formula.

In the drum, fP is the resonant frequency of the orifice in volume vb, volume Vb is the volume of chamber 16, The speed of sound in air is 344.8 rrv/s.

Vp is the volume of the opening (tunnel), and tP is the length of the tunnel of the opening. this The total amount is expressed in am, and the area of the opening is 0.2 x 1.6-”0.32 dm2. When the thickness of the judge is O, OidmC, the resonance frequency when the thickness is b-100dm3 fp will be about 42 Hz, and this value will be equal to the −”-absorption of this device 10a instead of 0 Hz. It approximately constitutes the limit frequency, which is the frequency when the structure is acoustically completely closed, i.e. If there is no equivalent aperture or slot 34, the theoretical limit frequency for absorption can be constructed. to be accomplished. If a tunnel with a length of ldm is connected to the opening, a frequency of about 25 Hz A resonant frequency is obtained. By incorporating apertures of the type described above, the dynamic characteristics of the acoustic system can be improved. properties and can change the damping of the system. A force 1 opening is incorporated. The stepwise function of the vibrating member is generally more rapid when the applied acoustic energy When the opening stops, uncontrolled vibrations occur as a result of the damaging damping of the vibratory motion, especially when the opening This may occur when the resonant frequency of the aperture is large and the resonant frequency of the aperture is also high. Therefore, A tunnel is connected to the opening, the resonant frequency fpk of the opening is kept low, and the vibration member is 14 natural resonant frequencies, or at least not far above them. That would be a suitable method. When it is desired to emphasize the increase in efficiency at the resonant frequency of the aperture 34, In this case, by incorporating a resonator aperture into the judge, it is possible to When applied to a range of wavenumbers, the area of the aperture 34 can be made even larger. , the resistance friction damping of the acoustic Q value in the case of the device 10a obtained at the resonant frequency of the aperture is Another slot-like or hole-like opening 36 according to FIGS. (schematically shown in the lower part of Figure 8). as you can clearly see The aperture 36 is provided with an acoustic flow resistance 37, which completely covers the aperture and with which The resonance effect is produced in the chamber volume Vb up to the range determined by the flow resistance 37 across the area of the opening 36. Short circuit.

This device therefore cooperates with an open acoustic aperture 34, according to FIGS. 9 and 10. The sharpness of the tuning of the aperture 34 is due to the presence of the resistive aperture 36 according to FIGS. 11 and 12. to reduce the amount of

The openings shown in FIGS. 11 and 12 are for the pressure chamber 16 in the device according to the invention. Although it can be effectively used as an equalization valve, the flow resistance is 14 and 15, and the acoustic chamber is not ventilated at all.

Figures 13 and 14 are a horizontal projection and a view, respectively, of the device 10b according to the invention. 2 and 3, the device is provided with an acoustic aperture 38, the aperture being directed towards the source of the sound. Resistively balanced against the chamber 16 and the vibrating member 14, the vibrating member 14 being substantially as shown in FIG. and a dynamic damping device 27 can be provided as shown in FIG. can.

The opening 38 is carried by the partition wall 15 facing the vibrating member 14 . vaginal wall 15 must be essentially passive to vibration, have a relatively high density, and must be able to absorb sound. can be done. The purpose of the openings 38 is to influence the sound absorption properties of the device 10b and to This occurs in the case of a sound whose characteristics mainly act only on the vibrating member 14, and the absorption is substantially The aim is to perform the process at an angle that approaches the organ shape. This causes this As a result of the device, the absorption in the case of a large angle of incidence with respect to the vibration direction of the vibrating member 14 is reduced. has been greatly improved, and the vibration part A'14 has good resistance damping characteristics, but it Acoustic resistance 3 through which the acoustic control aperture 38 passes through its acoustic arrangement and into said aperture facing the surroundings. This is because, as a result of the presence of 9, the sound from the vibrating member 14 is opposed. to this point The aperture 38 substantially reduces the acoustic resonance frequency when the device does not have the aperture 38. is given an area large enough to exceed the resonant frequency of the opening with the volume inside the chamber 16. It is necessary to

Applying the formula for Figures 9 and 10, the room volume is approximately 1,00 dm3. Using the product vb, the aperture area is about 2.5 dm2 and the aperture resonance frequency is about 70 Hz. The area of the opening 38 is approximately half of the total thickness area of the member 15. Hole mouth 3 an acoustic resistance in 8 acts at said aperture, and a device 10b with an aperture 38 exhibiting a resistance 39; The resonant frequency of is approximately restored to the resonant frequency of an equivalent device lacking devices 38 and 39. It needs to be adjusted so that This modification is shown in Figures 13 and 14. A dynamic flow valve 27 is attached to the vibrating member 14 in order to effectively and dynamically control the vibrating member 14. Ensure active vibration damping and selectively absorb and acoustically resist grooves as appropriate. It is particularly advantageous to arrange a wall 40 which is provided with holes 41 or holes and allows continuous air flow. Importantly, said walls are arranged symmetrically within the central part of the device 10b.

Figure 15 also shows a dynamic range of 50 dB and a lower limit frequency set at 20 H2. FIG. In the figure, the sound pressure level remains constant even if the frequency changes. It is said that In this way, the amplitude A (solid line) of the sound wave and its acceleration level The illustrated relationship between Δ (dashed lines) is obtained, in which case the slope of each function is 6 dB/octave. configure the server. The geometric mean frequency of the shear torque is 360Hz where the functions intersect. obtained in terms of. As you can clearly see, the acceleration level increases when the amplitude level approaches infinity. moves toward zero, and the amplitude increases as the frequency decreases from 360 Hz. The acceleration is greater than the wave acceleration, and the acceleration is within the frequency range where the frequency increases from 360 Hz. It's bigger than the swing width. A frequency spectrum with a limit frequency higher than 20 Hz is If taken into account, the average frequency points will be at evenly higher frequencies.

Within the frequency range where the amplitude is dominant, when the vibration amplitude of the absorbing surface also decreases in frequency, increase, i.e. double the frequency by half, and the absorption at the surface must remain constant. do not have.

As a result, the linear vibration amplitude at the absorbing surface is It must be possible to gradually increase the wave number (resonant frequency).Example: For example, if the lower limit frequency is set to 40 Hz, the vibration of the vibrating member in free air The mechanical resonance frequency is then at a somewhat lower frequency, for example 20 Hz, Expression of the volumetric parameters of the device with respect to the mechanical accommodation of the vibrating member and the spring stiffness of the air. The spring force allows the mechanical resonant frequency to increase and also increases the resultant acoustic resonant frequency. 40'Hz. Mathematically, this is approximately fa=fm ech. can be expressed as 100, in which case fa is the acoustic resonance frequency , fmech- is the mechanical resonance frequency, and Ō is the accommodation ratio related to the volume parameter ■b. It is. This adaptation ratio S can be calculated from the equation s = (8/fmech,)2-1 The resultant damping at the resonant frequency is η-Q and Q = fres /Cfu - fl), and in the case of (7), fu is the resonant frequency fre It has an amplitude 3 dB lower at frequencies higher than s, fl is lower than the resonant frequency, and 3 d B is a frequency with a low amplitude. When Q reaches 1.0, the acoustically closed circuit (resonant frequency essentially determined by the pressure function) is optimally damped and this value is difficult to achieve in practice.

FIG. 16 shows theoretically different functions of the acoustic absorption scheme according to the invention. top of figure shows the total acoustic absorption (solid line), and the dashed line on the left shows the vibration function αVib r, is indicated by the dashed line on the right, and is used for the device ] 0, for example, with the staple fiber surface layer. Mineral fiber absorption part with a core having a thickness of about 20 threads and a density of about 20 Kp/m3 The resistance absorption function αfric of the material 14 is shown.

The area of the absorbent material 14 is selected to be approximately 0.5 m2, and the volume of the chamber 16 is selected to be approximately 50 dm3. And, the resonance frequency fa of the absorber and the volume should be approximately 50 Hz as shown in the figure. Can be done. The absorption function of the member 14 is considered to be expressed in the range of 100 coefficient absorption. But it is about 1000H2Xffr to about 4000Hz.

flot: in which the absorber is measured in a reverberation chamber without conventional air gaps. determined. As you can clearly see, with this device, a vibration circuit and a resistance circuit can be obtained individually. Their effects are combined within a frequency range extending from 50Hz to 1kHz; Here both functions decrease. According to the theoretical model shown in Figure 16, the following applies. Ru. In the frequency range below the resonant frequency of 50 Hz, the absorption is approximately 12 dB/octave. Only the turb will decrease. Absorption in the first octave above the resonant frequency increases by about 3 dB, becomes constant in a complete system up to 4 kHz, and then decreases again. do. The induced absorption of this system can reach up to 100 coefficients, and the resonance frequency is 50 Hz. Resistance absorption 1d between 100Hz and 4000Hz It can never be more than 100%. The absorption device according to this invention, however, It constitutes a qualitatively balanced acoustic impedance and therefore a composite absorption of acoustic energy. The absorption must always exceed the absorption that is dominant in the resistance when only the vibrating member 14 is used. However, in the general case, 50H2 (resonant frequency of this system) and resistance cutting frequency 4k Hz, the absorption is larger than a factor of 100, and the absorption is shown at the top of Figure 16. is marked as the part of the level increased by 3 dB in the vibrating member 1. Approximately twice the absorption applied to 4 itself can be reached.

If a differential design of the acoustic device according to the invention is chosen, the vibrating surface is doubled and the synthetic absorption The acoustic absorption between mutually opposing members 14.15 is approximately 2 to 4 times the vibration surface used. can be increased as a result of binding. Furthermore, the acoustic resonance frequency is one of the masses ( Part 14) is passed through the other mass (part 15) of air placed in chamber 16. with the same volume and parameters as in the case of a single design. It will be roughly halved.

In order to make the best use of this invention when making a device according to the invention, the resonant frequency Good linearity is reliably obtained in the sensitive area at wavenumber fa and above. In that case, the comoving functions αVibr and αfric.

Both are in decreasing mode.

The invention provides a highly effective sound absorbing device with a very wide absorption range.

The described construction principle is extremely sensitive to the frequency range, absorption unidirectional, angularly incident acoustic energy and The correction of good amplitude linearity can be varied over a wide range, and the linearity described last may cause undesirable effects such as distortion components, random acoustics, and the occurrence of troublesome acoustic reflections. This is of great significance in order to avoid secondary effects. The device according to this invention It has an extremely fast gust response, and the propagation of sound waves adjacent to the vibrating member is very slow. Therefore, the direct reverberation is effectively suppressed, and the sound damping effect is In particular, it becomes extremely high for transient sounds. The so-called differential method mentioned above is based on the room acoustic condition. Extremely high noise levels containing large amounts of general regulation and even strong transient noise in the low frequency range Suitable for noise attenuation within a wide frequency range, it is because the differential method absorbs from both sides. This is because it exhibits a particularly high sound attenuation effect. Furthermore, a particularly advantageous feature of the invention is , due to its good reproducibility, possibility of use in one modality, and insertion effect. The insertion effect is essentially additive and greater than that obtained with conventional absorbent structures. allows much higher total attenuation within a given room and a much wider frequency range. Ru.

Claims (1)

[Claims] 1. Can be acoustically set to vibratory motion across a geometric plane extension, at least (16) A sound damping device comprising a thin plate material member (14) forming part of the partition wall of In the position, said member (14) is substantially free to swing and said chamber (16) is at least substantially acoustically occluded; and the device is at least substantially acoustically occluded; e.g., means for damping the displacement of said member [14] across said geometrical extension; The acoustic attenuation device is characterized in that it is combined with: 2 the member (14) is relatively thin, substantially planar and made of porous fibers or a perforated plate; and the plate is substantially fixed against vibrational movement in its edge section area. , when vibrating, the air-filled space (formed by 165) The volume of the air/filling space that cooperates with the member (14) to form the air spring is The oscillatory motion of said member (14) in relation to the density, mass and flow resistance of the device selected such that said maximum movement is maximum at the resonant frequency in said member (14). Claim No. The sound attenuation device according to item 1. 3 said member (14) is substantially symmetrical with respect to the rest of the member with respect to its geometric center; A claim characterized in that an area (27°31) of high air permeability is arranged. Range of the sound attenuating device according to item 1 or 2.4 The area (27) is characterized in that it is surrounded by a tubular part (29) arranged in the direction of vibration of the material (14). 4. The sound attenuating device according to claim 3, wherein the characteristics are: 5. The device comprises at least one opening (36), which opening is connected to the chamber [16]. A connection is made between the volume enclosed by the device and the volume surrounding said device, into which the resonant frequency of the device is placed. a flow resistance in an amount so as to substantially damp the amplitude of the vibratory motion of said member (14) in wave numbers; Any of claims 1 to 4 characterized in that a resistor (37) is arranged. 2. The sound attenuation device according to item 1. 6 the device comprises at least one acoustic aperture (34), said aperture opening into the chamber (16); connection between the volume enclosed by the device and the volume surrounding the device, and substantially connected to said member (14). by applying an acoustic load to the opening (34) and the resonance of the circuit formed by the aperture (34) and the surrounding volume. Claims 1 or 2 which substantially inductively increase the acoustic efficiency of this device with respect to frequency. The sound attenuation device according to any one of Items 5 to 6. 7. The aperture (34) also has a resistor (35) that weakens the acoustic coupling between the aperture and the member. ) The sound attenuating device according to claim 6, characterized in that the sound attenuating device exhibits: 8. The device comprises at least one acoustically resistive member (40), the member (40) comprising: the member (14) and a chamber compartment side part (15) placed opposite the member (14); and the acoustic resistance member (40) also has significant flow resistance. The sound damping device according to any one of claims 1 to 7, characterized in that: . 9 The chamber compartment side part (15) placed opposite the member (14) ) Claims 1 to 8 are characterized in that they are made of substantially the same member as The sound attenuating device according to any one of the above items. 10. At the chamber compartment side (1'5) placed opposite the member (14), the front The device also has an opening (38) of considerable size compared to the area of the member, and The opening (38) has an acoustic resistance (39) arranged therein, and the sound pressure reaching the surrounding area is Claim 1, characterized in that a sound pressure is generated at the opening of the opening in opposition to the 8. The sound attenuation device according to any one of Items 8 to 8.