GB2188186A - Controlling sound reverberation characteristics of a room - Google Patents
Controlling sound reverberation characteristics of a room Download PDFInfo
- Publication number
- GB2188186A GB2188186A GB08705590A GB8705590A GB2188186A GB 2188186 A GB2188186 A GB 2188186A GB 08705590 A GB08705590 A GB 08705590A GB 8705590 A GB8705590 A GB 8705590A GB 2188186 A GB2188186 A GB 2188186A
- Authority
- GB
- United Kingdom
- Prior art keywords
- absorber
- room
- sound
- panel
- reverberation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000006098 acoustic absorber Substances 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 14
- 239000006096 absorbing agent Substances 0.000 claims description 56
- 239000011248 coating agent Substances 0.000 claims description 2
- 238000000576 coating method Methods 0.000 claims description 2
- 239000002657 fibrous material Substances 0.000 claims description 2
- 230000004044 response Effects 0.000 description 12
- 238000010521 absorption reaction Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 3
- 230000010355 oscillation Effects 0.000 description 3
- 239000000835 fiber Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- ZYXYTGQFPZEUFX-UHFFFAOYSA-N benzpyrimoxan Chemical compound O1C(OCCC1)C=1C(=NC=NC=1)OCC1=CC=C(C=C1)C(F)(F)F ZYXYTGQFPZEUFX-UHFFFAOYSA-N 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000011491 glass wool Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/99—Room acoustics, i.e. forms of, or arrangements in, rooms for influencing or directing sound
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
- E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
- E04B1/62—Insulation or other protection; Elements or use of specified material therefor
- E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
- E04B1/82—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to sound only
- E04B2001/8263—Mounting of acoustical elements on supporting structure, e.g. framework or wall surface
- E04B2001/829—Flat elements mounted at an angle, e.g. right angle, to the supporting surface
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Acoustics & Sound (AREA)
- Electromagnetism (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Building Environments (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Apparatus for controlling the sound reverberation characteristics of a room comprises an acoustic absorber which may be mounted between the ceiling and a wall of the room, or in a corner. The acoustic absorber may be a panel which may be curved so as to be located in areas where the likely sound intensity will be particularly high. The reverberation characteristics of the room may be altered by changing the angle of the panel or deforming it. This may be done automatically so as to maintain the characteristics of the room substantially constant. The invention also extends to a method. <IMAGE>
Description
SPECIFICATION
Device and method for controlling sound reverberation in a room
The invention relates to a device and method for controlling sound reverberation in a room. It is particularly, though not exclusively, concerned with sound reflecting/absorbing members which are located in the angle between the walls and ceiling, or in the corners of a room.
Swedish Patent Application No. 8103345 discloses the use of planar diagonal absorbers arranged to adjust the sound pattern (including the time of reverberation) in a room. The frequency response is, however, not completely satisfactory as it is not sufficiently uniform.
According to a first aspect of the invention there is provided adjustable sound-reverberation control apparatus comprising an acoustic absorber and actuating means arranged to move the absorber, thereby selectively controlling the reverberation characteristics of a room.
According to a second aspect of the invention there is provided adjustable sound-reverberation control apparatus comprising an acoustic absorber, means for mounting the absorber to a wall or ceiling of a room, and actuating means arranged to move the absorber with respect to the mounting means, thereby selectively controlling the reverberation characterisics of a room.
According to a third aspect of the invention a method of controlling the sound reverberation characteristics of a room comprises measuring or calculating the sound pattern in the angle between adjacent walls, or between a wall and the ceiling, and selectively positioning an acoustic absorber in areas of locally high sound intensity.
According to a fourth aspect of the invention there is provided a method of controlling the soundreverberation characteristics of a room comprising automatically moving an acoustic absorber so as to maintain the reverberation characteristics of a room substantially constant.
The invention may be carried into practice in a number of ways and some specific examples will now be described, with reference to the accompanying drawings, in which
Figure 1 illustrates a known diagonal acoustic absorber situated in a corner of a room,
Figure 2 illustrates how the kinetic energy of the air molecules near the corner of a room varies with position when sound waves are set up within the room,
Figure 3 shows isoenergy lines based upon horizontal cuts through Figure 2; it also shows the possible positions of a number of diagonal acoustic absorbers,
Figure 4 illustrates the way in which the absorption coefficient x (in arbitary units) varies with frequency, for two different lengths I of the absorber,
Figure 5 illustrates a number of possible absorber types and positions and shows how the absorption coefficient varies with frequency for the various arrangements, and
Figure 6 is a graph showing how, for acoustic absorbers of various types, the specific flow resistance through the absorber material varies with the asborber density.
In all cases, means for mounting the absorber to a support (e.g. a wall, a ceiling or both) are not shown, but are implied.
At frequencies exceeding about 100-300 Hz, sound absorption in a thin absorber such as is shown in Figure 1 occurs as the air molecules move within the body of the porous material.
The frequency f1 at which the asborption is a maximum can be determined from a theoretical analysis of the sound field in a corner, viz:
where d is the depth of the absorber in metres, I is the length of the absorber in meters, and 0 is as indicated in
Figure 1.
At lower frequencies (50-200 Hz) and with diagonal absorbers where I is less than about 2m, most of the sound absorption occurs by the sheet material being induced to oscillate at its reonant frequency. Energy is therefore lost as a consequence of losses in the material and losses along the edges where the material is secured to the wall or ceiling.
For such resonant oscillations to be produced, the relative positions of the absorber and the regions in space at which the sound intensity is greatest (that is, where the pressure oscillation and mean molecule kinetic energy is greatest) are of importance.
For connection with a planar diagonal absorber of low bending resistance compared with the resistance of the confined air, the resonant frequency is:
where m is the mass of the sheet material per unit area in kg/m2 and I is the length of the sheet in metres.
The first process, at high frequencies, involves specific requirements as to size, shape, and flow resistance.
The second process, at low frequencies, involves specific requirements as to the size and mass per unit area.
The highest possible sound absorption is required, for practical purposes, in the frequency range 100-4000
Hz, and the absorption should preferably be as uniform as possible in that range.
Experiments with planar diagonal absorbers have given promising results when 1=0.90 m and 0=30 , and still better results can be expected in connection with particular, non-planar embodiments. Conversely, poor uniformity over the frequency range is to be expected with particularly disadvantageous embodiments.
Problems arise at low frequencies if the absorber dimensions are too small. Furthermore, the obtainable absorption area depends on the surface area of the absorber.
As the resonant frequency f0 should, in practice, be about 100 Hz, if I is assumed to be in the region of 0.90 to 1.80 m, the following requirements to the mass per unit area appear:
m=1-2 kg/m2
The mass per unit area must be highest for small values of I. Experiments have shown that the flow resistance of the material, which, as mentioned above, will affect its absorption characteristic, should be somewhat higher than that of traditional suspended ceiling plates, preferably about: r=2000-2500 Ns/m3. These values depend on the thickness h of the plate as well as on the material parameters according to the formulae: m=phandr==-h where p is the density and S is the specific flow resistance.
Thus, one obtains = 1.250 s-'
p This can be recorded in a --p-diagram as a straight line, see Figure 6. Also indicated on this graph are the corresponding lines for various fibrous materials. The position of the line defined above indicates that a good practical absorber should have a fibre diameter somewhat smaller than the fibre diameter of the usual glass wool. As an alternative a coating (either of the individual fibres or of the surface of the material) suitably increasing the flow resistance can be used.
In order to avoid high-frequency signals from being reflected from a too strongly compressed surface the specific flow resistance should not be too high. The parameters should preferably be selected within the following ranges: h p 20 mm 100 kg/m3 125.103 Ns/m4 40 mm 50 mg/m3 63.103 Ns/m4
Figures 5a-5e show how the absorption characteristics (in arbitary units) varies with frequency (in units of absorber size per wavelength) for differing embodiments of the absorber. Figure 5a shows an oval absorber providing a very non-uniform frequency response. As will be seen from the graph the frequency response shows a notch at c/X=0.7 corresponding to the absorber being situated, for sound of that wavelength, in positions with weak molecular oscillations.The diagonal absorber of Figure 5b also provides a very poor response since only a small part of the absorber is situated at the spot of high sound intensity. This arrangement is the one disclosed in Swedish Patent Application 8103745, mentioned earlier. A minor improvement is obtained by situating the diagonal absorber asymmetrically with an angle differing from 45".
Figure 3 illustrates the effect of such an absorber at different frequencies. It appears that with a planar absorber the response must necessarily show a notch (here at about 500 Hz). Figure 5d illustrates an ideal embodiment of the absorber member, the absorber being situated in areas where the sound is particularly intense. The distance between the crests is preferably about one half wavelength. Figure 5e illustrates an absorber of an alternative asymmetric embodiment, (as asymmetric L-shaped embodiment).
The acoustic absorbers of the present invention are optionally of variable configuration, for example so that the configuration, and thus the absorption characteristic with frequency, can be varied according to the resonance properties of the room at the time. These resonance or other acoustic properties may depend, for example, upon the number of persons in the room, ànd/orthe position of articles within the room. It is further desirable that the configuration may be altered in such a way that the frequency response remains substantially constant, as the natural acoustic properties of the room vary. In this way, the room can artificially be provided with a relevatively constant reverberation characteristic, independent of the number of persons or articles within the room. As an example, acoustic absorbers of the present invention could be used in a concert hall, and adjusted in response to the particular requirements of an orchestra, with regard to the time of reverberation and so on, while a concert is actually in progress. Furthermore, allowances can be made for variable numbers of people in the audience.
In one specific example, the adjustable configuration could be the angle between the absorber and the wall or ceiling of a room. This could be achieved by providing suitable means for varying the angle of the absorber, for example an electrical stepping motor, positioned immediately behind the absorber.
As an alternative, the adjustable configuration could be provided by the use of a deformable absorber, and some means (for example a series of actuator pistons pressing against the absorber on its rear side) to produce the deformation.
Both of the above arrangements could be provided for the same absorber.
In one particularly convenient arrangement, the configuration of the absorbers in a room is under microprocessor control. This could operate in several ways. If, for example, the natural resonance frequency of the room at any particular time is already known, and it is desired to change the acoustic properties of the room to give a different previously defined frequency response, then the microprocessor could simply be instructed to change the configuration of the absorbers to produce the required response. Alternatively, the microprocessor could be instructed to change the configuration so that the room has a particular desired frequency response, independent of the people or objects who are in it at the time.This could be achieved by providing means for determining the actual frequency characteristic of the room, comparing this with the desired frequency characteristic, and using the difference to make an appropriate alteration in the configuration. Naturally, it is not essential for the entire frequency characteristic of the room to be measured; it is sufficient for the sound pattern (in particular the sound intensities) near the corners of the room in which the absorbers are situated to be measured.
As a further alternative, the frequency response, reverberation characteristic, or sound pattern could be calculated rather than measured.
In one particular arrangement, the absorber is arranged to be moved in response to the actions of a player of a musical instrument within the room. The player can thus control not only the musical tones being produced by the instrument, but also the resonance characteristics of the room within which he is playing, so being able to control not only the notes played but also the timbre of the notes.
The absorbers of the present invention could be situated either in one or more of the corners of a room, or
between the edges of two adjacent walls, or between one or more walls and the ceiling. In the latter case, the absorber can act as a cornice. With any of the embodiments, particularly that shown in Figure 5e, the absorber
may be optionally used in connection with a perforated sound permeable underceiling which is flush with the absorber. This provides a good architectural effect.
Claims (27)
1. Adjustable sound-reverberation control apparatus comprising an acoustic absorber and actuating means arranged to move the absorber, thereby selectively controlling the reverberation characteristics of a
room.
2. Adjustable sound-reverberation control apparatus comprising an acoustic absorber, means for mount
ing the absorberto a wall or ceiling of a room, and actuating means arranged to move the absorber with
respect to the mounting means, thereby selectively controlling the reverberation characteristics of a room.
3. Apparatus as claimed in claim 1 or claim 2 in which the absorber comprises a sound absorbing panel.
4. Apparatus as claimed in claim 3 in which the panel is of a fibrous material,
5. Apparatus as claimed in claim 4 in which the panel includes a coating to increase the flow resistance thereof.
6. Apparatus as claimed in any one of claims 3 to 5 in which the panel is substantially planar.
7. Apparatus as claimed in any one of claims 3 to 5 in which the panel is asymmetrically L-shaped in cross-section.
8. Apparatus as claimed in any one of claims 3 to 5 in which the panel is wavy in cross-section.
9. Apparatus as claimed in any one of claims 3 to 8 in which the panel is elongate and has substantially
parallel longer sides, the apparatus being constructed and arranged for positioning the panel diagonally
between the wall and ceiling of a room.
10. Apparatus as claimed in any one of claims 3 to 8 in which the panel is generally triangular, the
apparatus being constructed and arranged for positioning the panel diagonally between the ceiling of a room
and two adjoining walls.
11. Apparatus as claimed in claim 9 or claim 10 in which the panel is arranged to be positioned asymmetrically with respect to the wall or walls, and ceiling.
12. Apparatus as claimed in any one of the preceding claims in which the actuating means are arranged to vary the angle of the absorber.
13. Apparatus as claimed in any one of the preceding claims in which the actuating means are arranged to
deform the absorber.
14. Apparatus as claimed in any one of the preceding claims including measuring means, arranged to
determine the sound pattern in the vicinity of the absorber, the actuating means being arranged to operate in
dependence upon an output of the measuring means.
15. Apparatus as claimed in claim 14 in which the actuating means is arranged to move the absorber into
an area of locally high soured intensity.
16. Apparatus as claimed in any one of the preceding claims in which the actuating means is arranged to operate under microprocessor control to move the absorber into one of a predefined plurality of positions.
17. Apparatus as claimed in any one of the preceding claims in which the actuating means is arranged to operate under microprocessor control to move the absorber into such positions as to cause a room in which the apparatus is situated to take on one of a predetermined plurality of selected resonance characteristics.
18. Apparatus as claimed in claim 17 arranged to operate so as to maintain the resonance characteristics of the room substantially constant.
19. Apparatus as claimed in any one of the preceding claims in combination with a musical instrument, the musical tones produced and their resonance characteristics being under the control of a player of the instrument.
20. A method of controlling the sound-reverberation characteristics of a room comprising measuring or calculating the sound pattern in the angle between adjacent walls, or between a wall and the ceiling, and selectively positioning an acoustic absprber in areas of locally high sound intensity.
21. A method as claimed in claim 20 in which the acoustic absorber is automatically moved to maintain the reverberation characteristics of a room substantially constant.
22. A method as claimed in claim 20 or claim 21 in which the absorber is a panel which has or is arranged to take up a wavy cross-section, the distance between a crest and a trough thereof being substantially one quarter of the wavelength of the sound within the room.
23. A method of controlling the sound-reverberation characteristics of a room comprising automatically moving an acoustic absorber so as to maintain the reverberation characteristics of a room substantially constant.
24. A method as claimed in any one of claims 20 to 23 comprising changing the angle of the absorber with respect to the walls or ceiling of the room.
25. A method as claimed in any one of claims 20 to 24 comprising deforming the absorber.
26. Sound reverberation control apparatus as specifically herein described with reference to any one of
Figures 5a, Sc,Sdor 5e; and with or without reference to Figure 3 and to Figure 6.
27. A method of controlling the sound-reverberation characteristics of a room substantially as specifically herein described.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DK112186A DK157819C (en) | 1986-03-11 | 1986-03-11 | PROCEDURE FOR REGULATING THE SOUNDFIELD IN A LOCATION |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8705590D0 GB8705590D0 (en) | 1987-04-15 |
| GB2188186A true GB2188186A (en) | 1987-09-23 |
| GB2188186B GB2188186B (en) | 1990-02-14 |
Family
ID=8101249
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8705590A Expired - Fee Related GB2188186B (en) | 1986-03-11 | 1987-03-10 | Device and method for controlling sound reverberation in a room |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS63113322A (en) |
| BE (1) | BE1000032A7 (en) |
| CA (1) | CA1294893C (en) |
| CH (1) | CH674043A5 (en) |
| DE (1) | DE3705438A1 (en) |
| DK (1) | DK157819C (en) |
| ES (1) | ES2002991A6 (en) |
| FI (1) | FI83117C (en) |
| FR (1) | FR2595856A1 (en) |
| GB (1) | GB2188186B (en) |
| GR (1) | GR870367B (en) |
| IE (1) | IE59607B1 (en) |
| IT (1) | IT1202617B (en) |
| NL (1) | NL8700513A (en) |
| NO (1) | NO870806L (en) |
| PT (1) | PT84453B (en) |
| SE (1) | SE8700983L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU669813B2 (en) * | 1993-09-01 | 1996-06-20 | Torrington Company Limited, The | Adjustable steering column assembly for a vehicle |
| WO2003002955A1 (en) * | 2001-06-28 | 2003-01-09 | Kkdk A/S | Method and system for modification of an acoustic environment |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB375726A (en) * | 1931-01-28 | 1932-06-30 | Marconi Wireless Telegraph Co | Improvements in or relating to acoustic adjusting apparatus for use in sound studiosand the like |
| GB496384A (en) * | 1936-03-26 | 1938-11-25 | Waldemar Oelsner | Improved means for controlling the acoustic properties of rooms |
| EP0037610A1 (en) * | 1980-04-09 | 1981-10-14 | Byggnadsfysik A & K AB | An arrangement for damping and absorption of sound in rooms |
-
1986
- 1986-03-11 DK DK112186A patent/DK157819C/en not_active IP Right Cessation
-
1987
- 1987-02-20 DE DE19873705438 patent/DE3705438A1/en not_active Withdrawn
- 1987-02-26 NO NO870806A patent/NO870806L/en unknown
- 1987-03-03 NL NL8700513A patent/NL8700513A/en not_active Application Discontinuation
- 1987-03-03 IT IT19558/87A patent/IT1202617B/en active
- 1987-03-05 GR GR870367A patent/GR870367B/en unknown
- 1987-03-06 FR FR8703086A patent/FR2595856A1/en active Pending
- 1987-03-06 ES ES8700626A patent/ES2002991A6/en not_active Expired
- 1987-03-06 CH CH845/87A patent/CH674043A5/de not_active IP Right Cessation
- 1987-03-09 FI FI871014A patent/FI83117C/en not_active IP Right Cessation
- 1987-03-10 GB GB8705590A patent/GB2188186B/en not_active Expired - Fee Related
- 1987-03-10 CA CA000531600A patent/CA1294893C/en not_active Expired
- 1987-03-10 SE SE8700983A patent/SE8700983L/en not_active Application Discontinuation
- 1987-03-10 IE IE60387A patent/IE59607B1/en not_active IP Right Cessation
- 1987-03-10 JP JP62053195A patent/JPS63113322A/en active Pending
- 1987-03-11 BE BE8700239A patent/BE1000032A7/en not_active IP Right Cessation
- 1987-03-11 PT PT84453A patent/PT84453B/en not_active IP Right Cessation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB375726A (en) * | 1931-01-28 | 1932-06-30 | Marconi Wireless Telegraph Co | Improvements in or relating to acoustic adjusting apparatus for use in sound studiosand the like |
| GB496384A (en) * | 1936-03-26 | 1938-11-25 | Waldemar Oelsner | Improved means for controlling the acoustic properties of rooms |
| EP0037610A1 (en) * | 1980-04-09 | 1981-10-14 | Byggnadsfysik A & K AB | An arrangement for damping and absorption of sound in rooms |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU669813B2 (en) * | 1993-09-01 | 1996-06-20 | Torrington Company Limited, The | Adjustable steering column assembly for a vehicle |
| WO2003002955A1 (en) * | 2001-06-28 | 2003-01-09 | Kkdk A/S | Method and system for modification of an acoustic environment |
Also Published As
| Publication number | Publication date |
|---|---|
| PT84453A (en) | 1987-04-01 |
| IE870603L (en) | 1987-09-11 |
| FI871014A0 (en) | 1987-03-09 |
| DK157819C (en) | 1990-09-10 |
| CA1294893C (en) | 1992-01-28 |
| DK112186D0 (en) | 1986-03-11 |
| GB8705590D0 (en) | 1987-04-15 |
| JPS63113322A (en) | 1988-05-18 |
| IE59607B1 (en) | 1994-03-09 |
| BE1000032A7 (en) | 1987-11-24 |
| SE8700983D0 (en) | 1987-03-10 |
| GB2188186B (en) | 1990-02-14 |
| DK157819B (en) | 1990-02-19 |
| NO870806D0 (en) | 1987-02-26 |
| NO870806L (en) | 1987-09-14 |
| FI83117C (en) | 1991-05-27 |
| IT1202617B (en) | 1989-02-09 |
| FI871014A (en) | 1987-09-12 |
| PT84453B (en) | 1989-10-04 |
| GR870367B (en) | 1987-07-10 |
| ES2002991A6 (en) | 1988-10-01 |
| SE8700983L (en) | 1987-09-12 |
| IT8719558A0 (en) | 1987-03-03 |
| NL8700513A (en) | 1987-10-01 |
| CH674043A5 (en) | 1990-04-30 |
| DK112186A (en) | 1987-09-12 |
| FR2595856A1 (en) | 1987-09-18 |
| DE3705438A1 (en) | 1987-09-17 |
| FI83117B (en) | 1991-02-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |