EP0411671B1 - Acoustic apparatus - Google Patents
Acoustic apparatus Download PDFInfo
- Publication number
- EP0411671B1 EP0411671B1 EP19900115030 EP90115030A EP0411671B1 EP 0411671 B1 EP0411671 B1 EP 0411671B1 EP 19900115030 EP19900115030 EP 19900115030 EP 90115030 A EP90115030 A EP 90115030A EP 0411671 B1 EP0411671 B1 EP 0411671B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- reflectors
- sound
- reflector
- acoustic
- acoustic system
- 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.)
- Expired - Lifetime
Links
Classifications
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods 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
- G10K11/18—Methods or devices for transmitting, conducting or directing sound
- G10K11/26—Sound-focusing or directing, e.g. scanning
- G10K11/28—Sound-focusing or directing, e.g. scanning using reflection, e.g. parabolic reflectors
Definitions
- the present invention relates to an acoustic system suitable for use in providing isolated acoustic zones in larger rooms such as exhibition halls or train stations.
- the invention relates to means for directing sound to a specific person or persons located at a specific space within a larger room, without disturbing surrounding people.
- Earphones In conference or lecture halls, selective listening is commonly done by the use of earphones in a headset. Earphones have the disadvantage of discomfort and considerable inconvenience when used over longer periods of time. Conventional loudspeakers do not provide sufficient directionality to be able to direct and restrict sound to a specific space. On the other hand, the principle of an acoustic lens is known for use in directing sound waves from a specific sound source to converge the sound waves.
- the United States Patent US-A-4,421,200 discloses an elliptically shaped transducer enclosure for sound transmission.
- An acoustically reflective shell is shaped in the form of an ellipsoid of revolution having two focal points along the elliptical axis.
- Transducers for sound transmission are placed at one of the distinct foci such that sound produced is reflected on the elliptical shell and directed substantially to the other foci.
- Two or more such reflective shells with respective transducers can be provided, whereby the sound generated by the transducers is focused and concentrated at a common focus.
- the United States Patent US-A-2,643,727 also discloses a sound transmitting device based on the use of an ellipsoidal reflector acting as an acoustic lens.
- the disclosed sound transmitting device comprises a loudspeaker diaphragm and a concave sound reflector in the form of an ellipsoid, the diaphragm being located at one focal point of the ellipsoid.
- the ellipsoidal surface is dimensioned such that the second focus lies outside of the reflector.
- Fig. 1 The basic principle of an ellipsoidal reflector acting as an acoustic lens is shown in Fig. 1. Examples of the use of acoustic reflectors are illustrated in Figs. 2 to 6.
- Fig. 1 indicates a hollow ellipsoid of revolution 1 having two foci 2, 3. Sound waves emanating from one of the focal points 2 are reflected by the inner surface of the ellipsoid 1 and directed to the other focus 3. The same principle would apply to light reflection.
- Figs. 2 and 3 illustrate the type of transmitting devices discussed in the above-mentioned US-A-2,643,272.
- reference numeral 10 denotes the surface of an ellipsoid of revolution
- the numeral 11 denotes a reflector the surface of which follows part of the ellipsoid.
- the reflector 11 is affixed to a wall 12, while in Fig. 3, the reflector 11 is affixed to a desk top 16.
- the reflector 11 is arranged such that the other focus B is located at a position where a person will be sitting, for example in a chair 14.
- a user 15 seated in the chair 14 will receive the sound from the loudspeaker 13, which has been reflected and directed substantially to his head portion.
- Such arrangements can be made to converge sound to a specific region and can function as a hearing aid for persons having difficulty in hearing. They can also be used for listening to music, whereby sound is concentrated to the listener at focus B, but is less audible to persons located outside of the reflector 11.
- Figs. 4, 5 and 6 illustrate further arrangements of reflector systems for concentrating and/or directing sound waves.
- the acoustic (sound) signal is conducted along a pipe 26 from a loudspeaker 22.
- An opening 27 is provided at the end of the sound conducting pipe 26, the end being located at the foci S 1 .
- the reflector surface 35 has a central portion formed as a paraboloid of revolution 35A, while the peripheral portion is formed as an ellipsoid of revolution 35B.
- a sound source is located at the focus S 1 .
- Fig. 6 illustrates an arrangement of a reflector 45, the figure showing a cross section in a plane lying orthogonal to a ellipsoidal axis containing the two foci. If the reflector were shaped as an ellipsoid of revolution about the axis, this cross section would be circular.
- the cross section is of elliptical shape, whereby the second focus is not at one point, but is broadened to become several foci in an area about what would have been the single second focus.
- the arrangement provides less concentration but an increased number of users is accommodated in the more broadly focused area.
- an acoustic system as defined in the attached Claim 1.
- Embodiments of the system are defined in the Claims 2 to 4.
- reflectors formed of an ellipsoidal surface are integrated into a ceiling panel for use in building construction.
- a plurality of such reflectors can be arranged in the ceiling of an exhibition hall, whereby isolated acoustic zones are created therebelow.
- a user can move into or out of the isolated acoustic zones to receive various but different acoustic information. For example, information can be given in different languages. Also, different music or different presentations can be provided in the independent acoustic spaces or zones created below the respective reflectors.
- Figs. 2 and 3 direct sound emanating from a source 13 at a focus A to be received by a user at a focus B.
- these devices can also be provided with a light reflecting surface.
- the concentrated light can serve to facilitate reading by the user.
- the user could visually confirm the position of the second focus B into which sound is to be converged, thereby facilitating the use of the device.
- the loudspeaker 22 is disposed outside of the reflector, thereby greatly reducing the interference of the reflected sound waves if the loudspeaker itself were located at the first focus S 1 . This becomes a problem for larger loudspeakers with a higher output.
- the reflector comprises an inner surface formed by a paraboloid of revolution 35A and a peripheral surface being an ellipsoid of revolution 35B. Sound emitted from the focus S 1 is reflected in parallel from the paraboloid surface 35A at the central portion of the reflector as shown in Fig. 5.
- the ellipsoidal surface provides a concentration of the reflected sound to the second focus S 2 .
- the area into which sound is directed is expanded about the second focus S 2 .
- Fig. 7 illustrates an embodiment of the present acoustic system by which two reflectors 51A, 51B are disposed at a predetermined distance from one another.
- Each of the reflectors 51A, 51B has an ellipsoidal surface of revolution having two foci along the ellipsoidal axis.
- a loudspeaker 52 is disposed in each reflector separately at the first focus position. Different sound signals are supplied to the two loudspeakers 52.
- each loudspeaker 52 The sound signals emanating from each loudspeaker 52 are reflected by the ellipsoidal surfaces and the sound waves 53 converge with directivity towards the other focus.
- Fig. 7 also shows sound level distributions which arise under the respective reflectors 51A, 51B. In this manner, independent acoustic zones or spaces are formed for the users 54.
- the solid line A is the sound pressure distribution (sound level) in dB of reflector 51A, while curve B is the distribution 51B.
- the distance between the two reflectors is 60 cm and the diameter of each reflector is 90 cm.
- the sound signals issuing from the loudspeakers are reflected and converged having sharp directivity as described above.
- the level of the surrounding background noise is 60 dB.
- the sound emanating from the reflector attenuates to the outside to a value falling below the background noise level.
- the sound under the reflector 51A is masked by the background noise and cannot be heard when standing under the other reflector 51B.
- independent acoustic zones are formed by the reflectors 51A, 51B respectively.
- the acoustic system of the present invention has numerous advantages in application.
- the acoustic system can be employed to present information of different content or in different languages.
- the present acoustic system can be used for the purpose of public address or announcements at only specific locations within the train station for those having slight or moderate hearing deficiencies.
- the present system can be optimally provided in special places for those who are hard of hearing.
- the acoustic system can be used for directing music to be heard only by a specific group of people. In addition, it could be used in a restaurant for making announcements to specific people. A practical application would also be the transmission of speech at international conferences or at training facilities.
- Fig. 8 illustrates a further embodiment of the invention in which the reflectors 51A, 51B are constructed integrally with a ceiling panel 55.
- the reflectors are incorporated as a part of the ceiling element.
- the acoustic system can be readily utilized in various building structures such as restaurants and conference halls.
- the present invention allows the transmission of a plurality of different sound signals to specific independent zones within a larger space.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Obtaining Desirable Characteristics In Audible-Bandwidth Transducers (AREA)
Description
- Figure 1
- is a diagram schematically illustrating the basic principle of an acoustic lens;
- Figures 2 and 3
- are schematic diagrams illustrating applications of an acoustic reflector;
- Figure 4
- is a cross sectional view of an apparatus employing a sound conducting pipe;
- Figure 5
- is a cross sectional view of an apparatus with another reflector surface;
- Figure 6
- is a cross sectional view of a reflector surface taken perpendicular to the main ellipsoidal axis;
- Figure 7
- is a schematic illustration of an acoustic system in accordance with an embodiment of the present invention;
- Figure 8
- is a perspective view illustrating a preferred embodiment of the present invention.
Claims (4)
- An acoustic system comprising:a plurality of reflectors (51A, 51B) each formed with an ellipsoidal surface having two foci on an axis, each reflector (51A, 51B) having an upper closed portion enveloping the upper one of said two foci and a downward open portion, said plurality of reflectors being disposed at a predetermined distance from each other; anda plurality of sound sources (52) respectively disposed at positions of the upper foci of said reflectors (51A, 51B) and directed upwardly,characterized in that the axes of the respective reflectors extend in substantially vertical direction and lie parallel to one another, whereby independent acoustic zones are formed below the respective reflectors (51A, 51B).
- The acoustic system of claim 1, wherein a sound pressure level on the axis of at least one of said reflectors (51A, 51B) is set to be higher by a predetermined value than a background noise level outside said one of said reflectors.
- The acoustic system of claim 2, wherein said predetermined distance is determined by spacing the vertical axes of the reflectors (51A, 51B) such that the sound level on the axis of any one reflector from its sound source attenuates radially to be lower than the background noise level at the position of the axes of any other of said reflectors (51A, 51B).
- The acoustic system of claim 1, 2 or 3, wherein the reflectors (51A, 51B) of the acoustic system are integrated into a ceiling panel (55) for use in building construction.
Applications Claiming Priority (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1202601A JPH0832113B2 (en) | 1989-08-04 | 1989-08-04 | Hearing aid |
JP1202602A JP2542563B2 (en) | 1989-08-04 | 1989-08-04 | Audio equipment |
JP202602/89 | 1989-08-04 | ||
JP202601/89 | 1989-08-04 | ||
JP2107441A JPH046599A (en) | 1990-04-25 | 1990-04-25 | Acoustic device |
JP107441/90 | 1990-04-25 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0411671A2 EP0411671A2 (en) | 1991-02-06 |
EP0411671A3 EP0411671A3 (en) | 1991-10-09 |
EP0411671B1 true EP0411671B1 (en) | 1998-05-13 |
Family
ID=27310975
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19900115030 Expired - Lifetime EP0411671B1 (en) | 1989-08-04 | 1990-08-03 | Acoustic apparatus |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0411671B1 (en) |
CA (1) | CA2022002C (en) |
DE (1) | DE69032304T2 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9084047B2 (en) | 2013-03-15 | 2015-07-14 | Richard O'Polka | Portable sound system |
US10149058B2 (en) | 2013-03-15 | 2018-12-04 | Richard O'Polka | Portable sound system |
US11950049B2 (en) | 2019-05-13 | 2024-04-02 | Sony Group Corporation | Acoustic reflector, speaker unit, and chair |
CN114991327B (en) * | 2022-06-30 | 2023-04-14 | 中国矿业大学 | Sound insulation and noise reduction device |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US1782801A (en) * | 1929-02-16 | 1930-11-25 | Baehn Frederick | Radio loud-speaker |
US2643727A (en) * | 1950-01-31 | 1953-06-30 | Elipson S A | Sound transmitting device with an ellipsoidal reflector |
DE2508494A1 (en) * | 1975-02-27 | 1976-09-02 | Hansrichard Dipl Phys D Schulz | Focuser for electromagnetic or mechanical waves - for therapeutic local hyper therapy of human tissue with ultrasonic or microwaves |
US4151584A (en) * | 1977-03-14 | 1979-04-24 | Electro Controls Inc. | Light-collecting reflector |
US4421200A (en) * | 1981-12-16 | 1983-12-20 | Ferralli Michael W | Elliptically shaped transducer enclosure |
-
1990
- 1990-07-26 CA CA 2022002 patent/CA2022002C/en not_active Expired - Fee Related
- 1990-08-03 EP EP19900115030 patent/EP0411671B1/en not_active Expired - Lifetime
- 1990-08-03 DE DE1990632304 patent/DE69032304T2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
CA2022002C (en) | 1999-10-05 |
EP0411671A2 (en) | 1991-02-06 |
CA2022002A1 (en) | 1991-02-05 |
DE69032304D1 (en) | 1998-06-18 |
EP0411671A3 (en) | 1991-10-09 |
DE69032304T2 (en) | 1999-02-04 |
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