EP0555787B1 - Combined active deresonator and ambience generator - Google Patents
Combined active deresonator and ambience generator Download PDFInfo
- Publication number
- EP0555787B1 EP0555787B1 EP93101873A EP93101873A EP0555787B1 EP 0555787 B1 EP0555787 B1 EP 0555787B1 EP 93101873 A EP93101873 A EP 93101873A EP 93101873 A EP93101873 A EP 93101873A EP 0555787 B1 EP0555787 B1 EP 0555787B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- room
- loudspeaker
- pressure
- electrical signal
- ambience generator
- 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
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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
- G10K15/00—Acoustics not otherwise provided for
- G10K15/08—Arrangements for producing a reverberation or echo sound
Definitions
- the present invention relates to a device to be used for changing the acoustic properties of a room, comprising a pressure transducer, a loudspeaker and an electronic control circuit adapted to generate, in response to pressure changes in the room, an electrical signal that serves to cancel the pressure change detected by the pressure transducer when it is reproduced through the loudspeaker.
- a loudspeaker means an entity constituted by one or more loudspeaker elements possibly operating over different frequency ranges.
- the listening space also has a great effect on the way how the music sounds. In most cases, the listening room is the greatest factor influencing sound reproduction.
- the acoustics of the listening room can be improved for instance by using different acoustic panels to line the walls and ceiling.
- Such passive methods are difficult to realize with frequencies below 200 Hz.
- the equipment described in the introduction has been presented, with which equipment room resonances can be attenuated or eliminated. This is based on the fact that the device can cancel low-frequency acoustic waves. Placed in a corner of a room, the device is able to attenuate standing waves present in said corner.
- Such a stand-alone active acoustic resonance suppressor has been described in the US patent 4,899,387. This apparatus is mounted in an upright, free-standing housing for eliminating unwanted reflected waves in a room.
- the housing is intended to be placed in a location where undesired wave patterns, such as standing waves, are formed in order to offset or cancel such conditions. These conditions are offset by generating an acoustic signal which is the inverse of pressure waves at a particular location.
- the pressure waves are sensed by a module, including a microphone which generates a corresponding electrical signal.
- This signal is sent to an electrical circuit where an inverse signal is created which is then transmitted to a loudspeaker.
- the loudspeaker output is directed toward the location where the standing waves would be formed.
- the loudspeaker output nulls local acoustic waves so that no standing waves are formed.
- the noise cancellation device described in this document is designed to attenuate noise present in the vehicle cabin which is generated by the vehicle engine.
- the car entertainment apparatus may contain a tuner, a compact disc player, a cassette player and the like.
- the device of the invention influences the properties of the room also with frequencies exceeding 200 Hz.
- the device of the invention further includes an ambience generator adapted to receive an electrical signal proportional to the sound present in the room and to generate, in response to said signal, a signal which produces an accoustic field containing early reflections and reverberation in the room when reproduced through the loudspeaker.
- the ambience generator receives the electrical signal proportional to the sound present in the room either directly from the sound reproduction equipment or through a microphone included in the equipment, said microphone most preferably being the same component that serves as a pressure transducer in connection with the control circuit.
- the pressure transducer is most preferably a pressure sensing microphone.
- FIG. 1 shows a circuit of the prior art for the active cancellation of low-frequency room resonances.
- This circuit comprises a pressure sensing microphone 1 adapted to feed a control circuit 3 the output of which has been connected to a loudspeaker 2.
- the pressure sensing microphone 1 senses the pressure present in the room at the location in which the device is placed.
- the control circuit 3 strives to maintain the pressure sensed by the pressure sensing microphone 1 at zero by generating a signal which, reproduced through the loudspeaker 2, cancels the pressure at the pressure sensing microphone 1. Thus a so called acoustic throat is created. If a positive pressure peak (acoustic wave) arrives at the pressure sensing microphone 1, the beam of the loudspeaker 2 will move backwards, whereupon the pressure at the microphone 1 decreases.
- a positive pressure peak acoustic wave
- the device "absorbs" the acoustic wave.
- the result is the elemination or attenuation of room resonances.
- the effective frequency range is about 20 - 200 Hz.
- Figure 2 shows a device of the invention for changing the acoustic properties of a room.
- This device comprises as a basis the device of Figure 1 in its entirety.
- the device comprises an ambience generator 4 which also feeds its output to the loudspeaker 2. Therefore, the outputs of the control circuit 3 and ambience generator 4 are summed at point 6.
- the loudspeaker 2 can be a loudspeaker capable of reproducing only low frequencies. In the device of the invention, however, the loudspeaker 2 must be able to reproduce the entire frequency band of the audio range, that is, about 20 to 20 000 Hz.
- the ambience generator 4 has been adapted to receive its control signal, which must be a signal proportional to the sound present in the space where the device is located, either directly from the sound reproduction equipment 5 or from the pressure sensing microphone 1.
- Figure 3 shows the acoustic waves present in a room when the listener 7 and the sound source 8 are stationed centrally in the room opposite one another.
- the listener 7 receives from the sound source 8 first a direct acoustic wave indicated with a large arrow and additionally early reflections indicated in solid line and reverberations indicated in broken line.
- the reverberation field must be dense enough and have sufficient duration.
- music reproduced in a room furnished with the equipment of the invention can sound the same as for instance in a concert hall.
- the ambience generator 4 is adapted to produce for instance signals of the kind shown in Figure 4.
- signals In this Figure, direct sound received by the ambience generator either directly in an electrical form from the sound reproduction equipment 5 or by "listening" in the room by means of a microphone, for instance a pressure sensing microphone 1, is illustrated furthest left on the time axis t.
- the ambience generator 4 In response to the signal received, the ambience generator 4 generates signals which have in Figure 4 been denoted as early reflections and reverberations. These are signals corresponding to direct sound, but they are appropriately delayed and attenuated.
- the reverberation produced by the ambience generator should preferably be adapted to the inherent reverberation of the room in order for the final result to be the optimum.
- the ambience generator is preferably able to generate several signal patterns of different types corresponding to Figure 4, and in these patterns the number and power level of the early reflections vary to some extent, as do the level and number of the reverberation signals.
- the device of the invention has been described mainly schematically by means of one exemplary embodiment, and it will be appreciated that the device described can be realized by means of electronic solutions of many different kinds without, however, departing from the essential idea of the invention as defined in the appended claims.
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Soundproofing, Sound Blocking, And Sound Damping (AREA)
- Circuit For Audible Band Transducer (AREA)
Description
- The present invention relates to a device to be used for changing the acoustic properties of a room, comprising a pressure transducer, a loudspeaker and an electronic control circuit adapted to generate, in response to pressure changes in the room, an electrical signal that serves to cancel the pressure change detected by the pressure transducer when it is reproduced through the loudspeaker. In the connection of this application, a loudspeaker means an entity constituted by one or more loudspeaker elements possibly operating over different frequency ranges.
- Often when good sound reproduction is the aim attention is paid solely to the properties of the sound reproduction equipment. The listening space also has a great effect on the way how the music sounds. In most cases, the listening room is the greatest factor influencing sound reproduction.
- The acoustics of the listening room can be improved for instance by using different acoustic panels to line the walls and ceiling. Such passive methods are difficult to realize with frequencies below 200 Hz. To solve problems presented by low frequencies, the equipment described in the introduction has been presented, with which equipment room resonances can be attenuated or eliminated. This is based on the fact that the device can cancel low-frequency acoustic waves. Placed in a corner of a room, the device is able to attenuate standing waves present in said corner. Such a stand-alone active acoustic resonance suppressor has been described in the US patent 4,899,387. This apparatus is mounted in an upright, free-standing housing for eliminating unwanted reflected waves in a room. The housing is intended to be placed in a location where undesired wave patterns, such as standing waves, are formed in order to offset or cancel such conditions. These conditions are offset by generating an acoustic signal which is the inverse of pressure waves at a particular location. The pressure waves are sensed by a module, including a microphone which generates a corresponding electrical signal. This signal is sent to an electrical circuit where an inverse signal is created which is then transmitted to a loudspeaker. The loudspeaker output is directed toward the location where the standing waves would be formed. The loudspeaker output nulls local acoustic waves so that no standing waves are formed.
- A combination of an adaptive noise cancellation device with a car entertainment apparatus is described in WO 90/09655.
- The noise cancellation device described in this document is designed to attenuate noise present in the vehicle cabin which is generated by the vehicle engine.
- The car entertainment apparatus may contain a tuner, a compact disc player, a cassette player and the like.
- In addition to room resonances described above early reflections and reverberation found at higher frequencies have a substantial effect on the character of the room as a listening space. A device of the kind described in the introduction has no effect on the properties of the space in this respect. Typically, a normal room has too little early reflection and the reverberation is too sparse and has too short duration.
- Solutions to add reverberation or to modify reverberation in acoustic space have been described e.g. in the US patent 5,025,472 or in an article by Geoffrey Berry and Gordon L. Crouse "Assisted Resonance" published in the Journal of the AES, April 1976.
- The importance of early reflections besides reverberation for a realistic acoustical room reproduction has been described in GB 22 55 884. This document discloses a signal processor creating the illusion of a sound source having an apparant distance from the listener.
- The device of the invention as it is defined in the appended claims influences the properties of the room also with frequencies exceeding 200 Hz. The device of the invention further includes an ambience generator adapted to receive an electrical signal proportional to the sound present in the room and to generate, in response to said signal, a signal which produces an accoustic field containing early reflections and reverberation in the room when reproduced through the loudspeaker. The ambience generator receives the electrical signal proportional to the sound present in the room either directly from the sound reproduction equipment or through a microphone included in the equipment, said microphone most preferably being the same component that serves as a pressure transducer in connection with the control circuit. Thus the pressure transducer is most preferably a pressure sensing microphone.
- In the following, the device of the invention will be described in more detail with reference to the accompanying drawing, wherein
- Figure 1 shows a device of the prior art for the attenuation of particularly low-frequency room resonances,
- Figure 2 shows a device according to the invention for changing the acoustic properties of a room,
- Figure 3 shows a room with acoustic waves present therein, and
- Figure 4 shows a signal generated by the ambience generator of the device of the invention on a time-power scale.
- Figure 1 shows a circuit of the prior art for the active cancellation of low-frequency room resonances. This circuit comprises a pressure sensing microphone 1 adapted to feed a
control circuit 3 the output of which has been connected to aloudspeaker 2. The pressure sensing microphone 1 senses the pressure present in the room at the location in which the device is placed. Thecontrol circuit 3 strives to maintain the pressure sensed by the pressure sensing microphone 1 at zero by generating a signal which, reproduced through theloudspeaker 2, cancels the pressure at the pressure sensing microphone 1. Thus a so called acoustic throat is created. If a positive pressure peak (acoustic wave) arrives at the pressure sensing microphone 1, the beam of theloudspeaker 2 will move backwards, whereupon the pressure at the microphone 1 decreases. Thus the device "absorbs" the acoustic wave. When the device is placed in a corner of a room, the result is the elemination or attenuation of room resonances. In practice, several such devices are needed in the room, and the effective frequency range is about 20 - 200 Hz. - Figure 2 shows a device of the invention for changing the acoustic properties of a room. This device according to Figure 2 comprises as a basis the device of Figure 1 in its entirety. In addition to this, the device comprises an ambience generator 4 which also feeds its output to the
loudspeaker 2. Therefore, the outputs of thecontrol circuit 3 and ambience generator 4 are summed atpoint 6. It may be stated that in the known solution of Figure 1, theloudspeaker 2 can be a loudspeaker capable of reproducing only low frequencies. In the device of the invention, however, theloudspeaker 2 must be able to reproduce the entire frequency band of the audio range, that is, about 20 to 20 000 Hz. In the device of the invention, the ambience generator 4 has been adapted to receive its control signal, which must be a signal proportional to the sound present in the space where the device is located, either directly from thesound reproduction equipment 5 or from the pressure sensing microphone 1. - Figure 3 shows the acoustic waves present in a room when the listener 7 and the sound source 8 are stationed centrally in the room opposite one another. In that situation, the listener 7 receives from the sound source 8 first a direct acoustic wave indicated with a large arrow and additionally early reflections indicated in solid line and reverberations indicated in broken line. There must be a sufficient quantity of early reflections, and also the reverberation field must be dense enough and have sufficient duration. Then music reproduced in a room furnished with the equipment of the invention can sound the same as for instance in a concert hall. Since there are too few early reflections and the reverberation is too sparse and short in a typical room, the ambience generator 4 is adapted to produce for instance signals of the kind shown in Figure 4. In this Figure, direct sound received by the ambience generator either directly in an electrical form from the
sound reproduction equipment 5 or by "listening" in the room by means of a microphone, for instance a pressure sensing microphone 1, is illustrated furthest left on the time axis t. In response to the signal received, the ambience generator 4 generates signals which have in Figure 4 been denoted as early reflections and reverberations. These are signals corresponding to direct sound, but they are appropriately delayed and attenuated. - The reverberation produced by the ambience generator should preferably be adapted to the inherent reverberation of the room in order for the final result to be the optimum. For this reason, the ambience generator is preferably able to generate several signal patterns of different types corresponding to Figure 4, and in these patterns the number and power level of the early reflections vary to some extent, as do the level and number of the reverberation signals. By adjusting the level and number of the early reflections and also the level and number of the reverberation signals, one can materially influence the way how the music sounds in the room in question.
- In the foregoing, the device of the invention has been described mainly schematically by means of one exemplary embodiment, and it will be appreciated that the device described can be realized by means of electronic solutions of many different kinds without, however, departing from the essential idea of the invention as defined in the appended claims.
Claims (5)
- A device to be used for changing the acoustic properties of a room, comprising a pressure transducer (1), a loudspeaker (2) and an electronic control circuit (3) adapted to generate, in response to pressure changes in the room, an electrical signal that serves to cancel the pressure change detected by the pressure transducer (1) when it is reproduced through the loudspeaker,
characterized in that the device further includes an ambience generator (4) adapted to receive an electrical signal proportional to the sound present in the room and to generate, in response to said signal, a second electrical signal which produces an acoustic field containing early reflections and reverberation in the room when reproduced through the loudspeaker (2). - A device as claimed in claim 1,
characterized in that the ambience generator (4) receives the electrical signal proportional to the sound present in the room directly from sound reproduction equipment (5). - A device as claimed in claim 1,
characterized in that the ambience generator (4) receives the electrical signal proportional to the sound present in the room from said pressure transducer (1). - A device as claimed in any one of claims 1 to 3,
characterized in that the pressure transducer is a pressure sensing microphone (1). - A device as claimed in any one of claims 1 to 4,
characterized in that the loudspeaker is a loudspeaker (2) for the entire audio range.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FI920608A FI94565C (en) | 1992-02-13 | 1992-02-13 | Device to be used for changing the acoustic properties of a room space |
FI920608 | 1992-02-13 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0555787A2 EP0555787A2 (en) | 1993-08-18 |
EP0555787A3 EP0555787A3 (en) | 1993-11-24 |
EP0555787B1 true EP0555787B1 (en) | 1997-05-14 |
Family
ID=8534580
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP93101873A Expired - Lifetime EP0555787B1 (en) | 1992-02-13 | 1993-02-06 | Combined active deresonator and ambience generator |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0555787B1 (en) |
JP (1) | JP3364260B2 (en) |
DE (1) | DE69310561T2 (en) |
FI (1) | FI94565C (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3920226B2 (en) | 2002-12-09 | 2007-05-30 | ティーオーエー株式会社 | Resonance frequency detection method, resonance frequency selection method, and resonance frequency detection apparatus |
JP4696142B2 (en) * | 2008-05-29 | 2011-06-08 | ティーオーエー株式会社 | Resonance frequency detection method and resonance frequency detection apparatus |
US8553898B2 (en) | 2009-11-30 | 2013-10-08 | Emmet Raftery | Method and system for reducing acoustical reverberations in an at least partially enclosed space |
CN112461437B (en) * | 2020-11-24 | 2022-07-05 | 深圳市锐尔觅移动通信有限公司 | Air pressure detection circuit, method, equipment and storage medium |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4899387A (en) * | 1988-12-02 | 1990-02-06 | Threshold Corporation | Active low frequency acoustic resonance suppressor |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2646210B2 (en) * | 1987-05-27 | 1997-08-27 | ヤマハ株式会社 | Electroacoustic reverberation support device |
GB8903201D0 (en) * | 1989-02-13 | 1989-03-30 | Lotus Group Plc | Noise suppression in vehicles |
-
1992
- 1992-02-13 FI FI920608A patent/FI94565C/en active
-
1993
- 1993-02-06 EP EP93101873A patent/EP0555787B1/en not_active Expired - Lifetime
- 1993-02-06 DE DE1993610561 patent/DE69310561T2/en not_active Expired - Fee Related
- 1993-02-12 JP JP02441593A patent/JP3364260B2/en not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4899387A (en) * | 1988-12-02 | 1990-02-06 | Threshold Corporation | Active low frequency acoustic resonance suppressor |
Also Published As
Publication number | Publication date |
---|---|
DE69310561T2 (en) | 1997-11-13 |
FI920608A0 (en) | 1992-02-13 |
DE69310561D1 (en) | 1997-06-19 |
JP3364260B2 (en) | 2003-01-08 |
FI920608A (en) | 1993-08-14 |
EP0555787A3 (en) | 1993-11-24 |
FI94565C (en) | 1995-09-25 |
FI94565B (en) | 1995-06-15 |
EP0555787A2 (en) | 1993-08-18 |
JPH05346792A (en) | 1993-12-27 |
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