CA2000599A1 - System for modifying acoustic environment - Google Patents

System for modifying acoustic environment

Info

Publication number
CA2000599A1
CA2000599A1 CA002000599A CA2000599A CA2000599A1 CA 2000599 A1 CA2000599 A1 CA 2000599A1 CA 002000599 A CA002000599 A CA 002000599A CA 2000599 A CA2000599 A CA 2000599A CA 2000599 A1 CA2000599 A1 CA 2000599A1
Authority
CA
Canada
Prior art keywords
control means
module
acoustic
absorption
variable
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.)
Abandoned
Application number
CA002000599A
Other languages
French (fr)
Inventor
John F. Russell
Grant N. Pearce
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of CA2000599A1 publication Critical patent/CA2000599A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G10MUSICAL INSTRUMENTS; ACOUSTICS
    • G10KSOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/002Devices for damping, suppressing, obstructing or conducting sound in acoustic devices
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/99Room acoustics, i.e. forms of, or arrangements in, rooms for influencing or directing sound
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82Heat, 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
    • E04B1/84Sound-absorbing elements
    • E04B2001/8423Tray or frame type panels or blocks, with or without acoustical filling
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B1/00Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
    • E04B1/62Insulation or other protection; Elements or use of specified material therefor
    • E04B1/74Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
    • E04B1/82Heat, 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
    • E04B1/84Sound-absorbing elements
    • E04B2001/8423Tray or frame type panels or blocks, with or without acoustical filling
    • E04B2001/8428Tray or frame type panels or blocks, with or without acoustical filling containing specially shaped acoustical bodies, e.g. funnels, egg-crates, fanfolds

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Architecture (AREA)
  • Electromagnetism (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Multimedia (AREA)
  • Building Environments (AREA)

Abstract

ABSTRACT

A system for modifying an acoustic environment (10), which in an embodiment may be a recording studio, by the provision of modular absorption and/or diffusion elements (12) which can be located at the walls or ceiling of the space constituting the acoustic environment. Each modular element (12) may be one of three types; the first type providing variable absorption, the second type providing variable absorption in a mutually exclusive frequency range to the first type, and the third type providing variable absorption or alternatively diffusion over a broad frequency range.
Each modular element (12) contains a local control means (11) to effect the variation, and an external actuation sensor (21) for manual control over each modular element (12). There are also one or more transducers (14) and a noise source (15) located within the space which provide a determination of the actual acoustic environment. All of the modular elements (12), transducers (14) and noise source (15) are interconnected to a remote control means (16) by a data bus (18). The remote control means (16) comprises an I/O controller (17), a processor (24), a memory (25), an input device (20) and a display device (28). The remote control means (16) provides for control over the variable acoustical components within each modular element (12). In one embodiment, the remote control means (16) may be situated in the control room of a recording studio.

Description

~ `

~OQS99 SYSTEM FOR MODIFYING ACOUSTIC ENVIRONMENT
This invention relates to a system for modifying an acoustic environment.

It is well known that the acoustic environment 10 of an enclosed or semi-enclosed space can be modified so as to achieve a desired acoustic performance. In spaces such as recording studios, auditoria or sound shells in ~',',-'.' .

zooos99 open air theatres, it is often desirable to modify the acoustic properties therein in accordance with the type of performance or use.
Typically, regard will be had to the 5 reverberant, direct and near field performance with respect to frequency, and such characteristics may be modified by the use of appropriate acoustic treatments in the form of absorption, reflection or diffusion devices.
Acoustic absorption devices are normally 10 applied to walls, ceilings or floors, but could also be -~
free standing, consisting typically of porous absorbers, panel absorbers or volume resonators. Reflective - -treatments have the converse effect, providing very -~
little acoustic absorption and increasing the reverberant lS sound pressure level, while diffusing treatments tend to -compensate for the frequency dependent directionality of acoustic waves. --~
In the prior art, these treatments are usually ~-fixed in the acoustic space to suit one particular type ~-20 of performance, and in those multi-purpose performance spaces, particularly recording studios where adjustment is required, the expenditure of substantial time and effort in relocating or introducing such devices, which -can be very large, leads to delays and inconvenience in ~-25 adapting the space between uses. It is also not normally possible to modify the acoustic environment during a -~-performance or use.

An object of the invention is to overcome these 30 disadvantages.
Therefore, according to one aspect of the invention, there is provided a system for modifying an -acoustic environment, comprising:
a plurality of modular elements for providing -35 variable acoustic absorption and/or diffusion; and ~ ,-~ )QS99 ;
control means to effect the variation of the acoustic absorption and/or diffusion of said modular elements.
According to a further a~pect of the invention, 5 there is provided a system for controlling the acoustic environment of an enclosed space, comprising:
a combination of modules located on some or all of the walls and ceiling defining the enclosed space, the modules comprising in any combination:
a first type of module for providing a variable low frequency panel absorber having one or more chambers of variable depth therein with each chamber being covered with a damped membrane enclosing the entrance to said chamber, a second type of module for providing a retractable mid to high frequency porous absorber, and a third type of module for providing a :
retractable mid to low frequency porous absorber adapted to be located in front of one or more variable volume 20 cavity diffusers;
said system also comprising local control means within each of the modules, said local control means adapted to provide actuation of the variable or retractable element in each type of module and being 25 operable from a remote control means in communication therewith for providing for the variation of the acoustic environment.

A preferred embodiment of the invention will be 30 described by way of example with reference to the accompanying drawings wherein:
Figure 1 is a schematic representation of a system in accordance with the embodiment;
Figure 2 shows further detail of the local 35 control means of Figure l;

~. ;.~, ~ ... ,, -, .
a~

Figure 3 shows an example of a display presented to an operator of the system;
Figure 4 is an isometric view of a low frequency module in the embodiment7 5Figure 5 is a sectional view of the low frequency module of Figure 4;
Figure 6 is an isometric view of a mid to high frequency module in the embodiment;
Figure 7 is a sectional view of the mid to high 10 frequency module of Figure 6;
Figure 8 is an isometric view of a diffusion module in the embodiment; and Figure 9 is a sectional view of the diffusion module shown in Figure 8.

The embodiment will be discussed with reference to a recording studio representing the acoustic space to which the system may be applied. The system could be --equally applied in other embodiments to theatres, 20 auditoria, sound shells or the like.
Figure 1 shows a system for modifying the -acoustic environment of an enclosed or semi-enclosed ~ -space. In the studio (10) within which the acoustic environment is to be modified, it is typically desirable 25 to adjust the reverberation time and the diffusion characteristics of the volume therein in accordance with -the performance or use. Reverberation time is a function of volume and acoustic absorption, so while the volume of -a space cannot be easily changed, it is possible, in 30 accordance with the system, to increase or decrease the amount of acoustic absorption. Similarly, diffusion devices can be added to overcome the directionality of the various frequency components, thereby avoiding so-called bright or dead spots.
, 2~Q599 In the system shown, the acoustic environment of the studio (10) contains a plurality of modular elements (12) providing variously absorption and diffusion, which can be applied to the walls, floors or 5 ceiling of the studio, or indeed could be free standing.
Each of the modular elements (12) contain a local control means (11) to vary the amount of acoustic absorption or diffusion provided. The local control means (11) is connected to an I/0 controller (17) in a remote control 10 means (16) via a data bus (18). The remote control means (16) is typically located in a control room associated with the studio (10). In addition, the studio (10) may also comprise a plurality of measurement transducers (14) located within the space, which are also connected to the 15 remote control means (16) via bus (18), as is a noise source (15).
Each local control means (11) also has an external actuation sensor (21) which is typically a laser sensing device tuned to a particular wavelength of light, 20 which allows an operator of the system to control the various modular elements (12) from within the studio (10) through use of a hand-held laser pointer.
The remote control means (16) further includes a processor (24), memory (25), and input device (20) and 25 a display device (28). The remote control means (16) allows an operator of the system to have control over the acoustic environment within the studio (10). The display device (28) can alternatively display an indication of the acoustic environment, or a detailed plan relating to 30 the set-up of the various modular elements (12), as is shown in Figure 3. The operator is free to modify the set-up via the input device (20) which can be a keyboard/mouse combination. All functions are under the -control of the processor (24). In addition, the memory `, :,. - , (25) can store previous set-up configurations for the studio, thus enabling the operator to select that desired set-up quickly thereby saving further studio time.
The operator also has the facility of measuring 5 the actual acoustic environment within the studio (10) through the agency of the noise source (15). The noise source (15) could be a white, pink or band-limited random noise generator, and through determination of reverberation time taken from a decaying sound pressure 10 level measurement by the transducers (14), the total absorption within the space will be known, and hence also the reverberant performance of the studio (10).
Referring to Figure 2, further details of tile local control means (11) within each modular element (12) 15 are shown. The external actuation sensor (21) and data bus (18) are shown as common with Figure 1. The drive circuit (30) is in communication with the I/O controller (17) of the remote control means (16) via data bus (18), and with the sensor (21) and the position transducer 20 (29). The position transducer (29) determines the relative extension or travel of the acoustic treatment within each modular element (12) by any suitable encoding or sensing technique such as limit switches, shaft encoders, or optical beams. In some instances, there may 25 be more than one drive circuit (30) and position transducer (2g), as the relevant module (12) may contain two or more variable acoustic treatments. A duplicated configuration exemplifying this is shown in shadow in Figure 2.
i As discussed briefly above, Figure 3 shows an example of a display presented to an operator of the system by the display device (28) relating the actual set-up of the various modular elements (12) within the studio (10). The example presented indicates that the 35 studio (10) has modular elements (12) placed in each of ` ~`
its walls, and on the ceiling. The adjust,ment of each .

X~)QS99 _ 7 _ particular element can be made using a mouse as80ciated with the input device ~20), and a positioning/selecting interactive operation with the display.
Figuxe 4 shows an example of a first type of 5 modular element (12) as shown in Figure 1, that being a low frequency module (31). The module shown comprises dual absorbers constituted by the left hand membrane facing (34) and enclosured volume (32) (obscured), and secondly a membrane facing (35) (shown in an exploded 10 view) and enclosed volume (36). The low frequency module (31) is effectively two panel resonators. The resonant frequency and hence absorption characteristic with frequency of these panel resonators is a function of the enclosed volume and the mass density (damping) of the 15 membrane facing. The enclosed volume in each half is independently variable. Shown is movable panel (38) in conjunction with gear track (40) in one half.
The low frequency module (31) is adapted to be fixed onto an existing wall, or can be incorporated into 20 the wall either during or after construction of a studio.
Suitable mounted brackets (37) are also shown. The location of the external actuation sensor (21) is shown mounted at membrane facing (35).
Figure 5 shows a sectional view of the module 25 shown in Figure 4. The movable panel (38) moves along the gear track (40). The membrane facing (35) is shown, as is a transport mechanism (41) being equivalent to drive circuit (30) and position sensor (29) of the local control means (11). The transport mechanism (41) 30 includes a stepper motor (42) which is connected to toothed pulleys (43) which mesh with the gear track (40) to move the movable panel (38). ~-Figure 6 shows an example of a second type of module (12) as shown in Figure 1, that being a mid to 35 high frequency module (50). The module (50) forms an enclosure which comprises the absorbent facing (54) .~. ~.. .

,`' ,'~'. ~ .. . ~. . . ' :

r~

2~)0599 located at the incident face of the enclosure with respect to sound waves. The amount of absorption is controlled by this facing, which can be retracted or extended vertically to its full or some partial extent 5 via a transport mechanism (58) (not shown). The absorption frequency characteristic will be determined by the material used as the facing. In this fiqure, the facing (54) is shown partially extended. When the facing (54) is fully retracted, the module acts as a 10 diffuse reflector by means of the angled panels (56) in the respective halves of the enclosure. The angle of the panels (56) determines the diffusion characteristic of the module with frequenay. The external actuation sensor (21) is also shown.
Figure 7 shows a sectional view of the module (50) shown in Figure 6. The facing (54) is shown connected to a transport mechanism (58) being equivalent to drive circuit (30) and position transducer (29) of the local control means (11). The transport mechanism (58) ;~
20 comprises a stepper motor (57) and a continuous drive belt (59) connected to pulleys (55) which enable -~
extension or retraction of the facing (54).
The angle formed by-the angled panels with .
respect to the plane of the absorbent facing (54) may be 25 varied between different mid to high frequency modules (50) to provide a good spread of diffuse reflection capability with frequency. -Figure 8 shows an example of a third type of module (12) as shown in Figure 1, that being a diffuser 30 module (60). The module (60) includes a retractable absorbent facing (64) (shown partially extended). The absorption is controlled by this facing (64), which can be retracted or extended vertically to its full or partial extent via a transport mechanism (68) (not -35 shown). When the absorbent facing (64) is fully retracted, the module (60) acts as a variaple quadratic --;

:~'`''-r~

s99 diffusion device, with the volume of the independent chambers (66) providing differing diffusion characteristics with frequency. The volume of each of these chambers may be adjustable via any suitable drive 5 mechanism in the same way as for the low frequency absorber of Figures 4 and 5. That is, if the diffuser module (60) is to provide variable a volume for any chamber (66), the number of drive circuits (30) within the local control means (11) will be equal to the number 10 of chambers (66) plus one, to account for the facing (64). In the present example, the volume described by each of the chambers (66) is fixed, yet different for each separate chamber to achieve good frequency coverage.
Figure 9 is a sectional view of the diffuser 15 module (60) shown in Figure 8. The absorbent facing (64) is shown connected to a transport mechanism (68), being equivalent to drive circuit (30) and position transducer (29). The transport mechanism (68) comprises a stepper motor (70), and a continuous drive belt (69) connected to 20 pulleys (71~ which enable extension or retraction of the absorbent facing (64). The backplane (72) of the chamber (66) is shown, as are the mounting rackets (37).
Therefore, in operation of the system described in the embodiment, the acoustic performance 25 characteristics of the studio (10) can be easily adjusted either before or during a performance in the studio by the operator in the control room through simple interfacing with the remote control means (16), which could conveniently be a personal computer equipped with a 30 mouse. The operator can adjust the amount of absorption, diffusion or diffuse reflection provided by the configuration of modular elements in the studio.
Alternatively, each module could be operated individually from within the studio using a laser light pointer in 35 conjunction with a suitable actuation sensor (21) in each module (12).

. -" ~

.~ -, . . .

- 2~00599 A personal computer could be adapted to store previous set-ups, or to automatically compensate the acoustic performance of the studio during a performance by continual monitoring of reverberant levels through the S agency of sound level meters and other appropriate electronic signal processing equipment.
As a further possibility, the operation of the system could be performed with the remote control means (16) located well away from the studio control room by 10 use of any suitable known communication link.

, '~

.~, , - ,. ~

: -

Claims (22)

WE CLAIM:
1. A system for modifying an acoustic environment, comprising:
a plurality of modular elements for providing variable acoustic absorption and/or diffusion; and control means to effect the variation of the acoustic absorption and/or diffusion of said modular elements.
2. A system as claimed in Claim 1, wherein the control means comprises a local control means within each modular element, and a remote control means adapted to control each of said local control means.
3. A system as claimed in Claims 1 or 2 wherein the acoustic environment is a theatre, auditorium or studio.
4. A system as claimed in any one of the preceding claims, wherein the modular elements are located on the walls or ceiling of an enclosed or semi-enclosed space.
5. A system as claimed in any one of the preceding claims, wherein the modular elements in the system include any combination of:
a first module for providing acoustic absorption, a second module for providing acoustic absorption in a mutually exclusive frequency range to the first module, and a third module for providing absorption or alternatively diffusion.
6. A system as claimed in Claim 5, wherein the first module comprises a variable low frequency panel absorber having one or more chambers of variable depth each with an associated damped membrane enclosing the entrance to the said chamber, said second module comprises a retractable mid to high frequency porous absorber, and said third module comprises a retractable mid to low frequency porous absorber adapted to be located in front of one or more variable volume cavity diffusers.
7. A system as claimed in Claim 6, wherein the local control means provides the control of the depth of the one or more chambers in the first module, control of the extension of the porous absorber within the range of fully retracted to fully extended in the second module, and control of the extension of the porous absorber within the range of fully retracted to fully extended in the third module.
8. A system as claimed in Claim 7 wherein the local control means comprise stepper motors responsive to commands from the remote control means.
9. A system as claimed in any one of Claims 2 to 7, wherein the local control means are also responsive to a manual actuation signal.
10. A system as claimed in Claim 9, further comprising a detector mounted integral with each modular element, and wherein the manual actuation signal is provided by a laser signal detected by the detector.
11. A system as claimed in Claim 2, wherein the remote control means comprises an electromagnetic transmission device and the local control means comprises an electromagnetic reception device.
12. A system as claimed in Claim 11, wherein the electromagnetic transmission is a laser beam.
13. A system as claimed in any one of Claims 2 to 7, wherein the remote control means comprises an operator station so that an operator can selectively operate each local control means.
14. A system as claimed in Claim 13, wherein the operator station comprises an input means to provide for the operation of the said local control means in each modular element, a display means for display of the operational condition of each modular element or display of an indication of the actual acoustic environment, and a storage means to store actual control configurations of the modular elements in a desired set-up.
15. A system as claimed in either of Claims 13 or 14, wherein the operator station is adapted to provide automatic adjustment of the acoustic environment based on predetermined acoustic parameters and measurements of actual performance parameters in the acoustic environment.
16. A system as claimed in Claim 6, wherein the local control means in the third module is adapted to provide variable diffusion performance by varying the volume of the respective cavity diffusers.
17. A system for controlling the acoustic environment of an enclosed space, comprising:
a combination of modules located on some or all of the walls and ceiling defining the enclosed space, the modules comprising in any combination:
a first type of module for providing a variable low frequency panel absorber having one or more chambers of variable depth therein with each chamber being covered with a damped membrane enclosing the entrance to said chamber, a second type of module for providing a retractable mid to high frequency porous absorber, and a third type of module for providing a retractable mid to low frequency porous absorber adapted to be located in front of one or more variable volume cavity diffusers;
said system also comprising local control means within each of the modules, said local control means adapted to provide actuation of the variable or retractable element in each type of module and being operable from a remote control means in communication therewith for providing for the variation of the acoustic environment.
18. A system as claimed in Claim 17, wherein the local control means are independently operable by external means.
19. A system as claimed in Claim 18, wherein the external means is a laser pointer, and each local control means incorporates a light detector responsive to the frequency of the laser light.
20. A first acoustic module for providing variable low frequency absorption comprising, one or more chambers of variable depth each with an associated damped membrane enclosing the entrance to the said chamber, and a control means for achieving a change in the volume of any of said chambers.
21. A second acoustic module for providing variable mid to high frequency absorption comprising, a retractable porous absorber, and a control means for controlling the extent of extension thereby adjusting the amount of acoustic absorption provided by the said second module.
22. A third acoustic module for providing variable mid to low frequency absorption comprising, a retractable porous absorber located in front of one or more cavity diffusers of the same or different volume, and control means for controlling the extent of extension of the absorber thereby adjusting the amount of acoustic absorption in mutual exclusivity to the provision of broad band diffusion by the diffusers.
CA002000599A 1988-10-12 1989-10-12 System for modifying acoustic environment Abandoned CA2000599A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPJ0916 1988-10-12
AUPJ091688 1988-10-12

Publications (1)

Publication Number Publication Date
CA2000599A1 true CA2000599A1 (en) 1990-04-12

Family

ID=3773438

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002000599A Abandoned CA2000599A1 (en) 1988-10-12 1989-10-12 System for modifying acoustic environment

Country Status (2)

Country Link
CA (1) CA2000599A1 (en)
WO (1) WO1990004071A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5525765A (en) * 1993-09-08 1996-06-11 Wenger Corporation Acoustical virtual environment
WO2003002955A1 (en) * 2001-06-28 2003-01-09 Kkdk A/S Method and system for modification of an acoustic environment

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2277983A (en) * 1942-03-31 Acoustical apparatus
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
DE589790C (en) * 1931-12-20 1933-12-13 Tobis Tonbild Syndikat Akt Ges Device for regulating the reverberation in sound recording and playback rooms
US1903201A (en) * 1932-09-08 1933-03-28 Jacques B Steur Sound modifying device
US3447628A (en) * 1966-10-31 1969-06-03 Foey M Shiflet Control system for synchronously controlling the opposed rotation of acoustical elements about coincident or parallel axes
US4665549A (en) * 1985-12-18 1987-05-12 Nelson Industries Inc. Hybrid active silencer

Also Published As

Publication number Publication date
WO1990004071A1 (en) 1990-04-19

Similar Documents

Publication Publication Date Title
Honcharenko et al. Mechanisms governing UHF propagation on single floors in modern office buildings
EP0722526B1 (en) Acoustical virtual environment
US5512715A (en) Sound absorber
US4821839A (en) Sound absorbing diffusor
Barron et al. Energy relations in concert auditoriums. I
US20160024783A1 (en) Dynamically adjustable acoustic panel device, system and method
CA1154689A (en) Method and apparatus for masking sound
Guicking et al. Coherent active methods for applications in room acoustics
Bistafa et al. Predicting speech metrics in a simulated classroom with varied sound absorption
US4219101A (en) Acoustic space divider
Hodgson Measurements of the influence of fittings and roof pitch on the sound field in panel-roof factories
CA2000599A1 (en) System for modifying acoustic environment
Wolfle et al. Field strength prediction in indoor environments with neural networks
MY105369A (en) Arrangement for the waveguide-free bidirectional light or infrared transmission of electrical signal.
US6119808A (en) Transportable acoustic screening chamber for testing sound emitters
Davies et al. New attributes of seat dip attenuation
WO2003002955A1 (en) Method and system for modification of an acoustic environment
CA2328265A1 (en) Air-coupled surface wave structures for sound field modification
JP2924086B2 (en) Monitor system for immunity measurement
Viveiros et al. An image model for predicting the field performance of acoustic louvres from impulse measurements
Romeu et al. Reduction of noise transmission through an aperture using active feedforward noise control
Bloemhof Note on the relationship of sound pressure and sound intensity
US20050047607A1 (en) System and method for sharing acoustical signal control among acoustical virtual environments
CN217283384U (en) Reverberation time adjustable voice test room
Eargle Control Rooms and the Monitoring Environment

Legal Events

Date Code Title Description
FZDE Discontinued