JP3364260B2 - A device that changes the acoustic characteristics of a room - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention comprises a pressure transducer, a loudspeaker and an electronic control circuit , the electrical signal acting to cancel the pressure change detected by the pressure transducer when reproduced by the loudspeaker. Relates to a device for changing acoustic characteristics of a room, which is configured to be generated in response to a pressure change in the room. In this specification, the term "loudspeaker" means a loudspeaker constituted by one or more loudspeaker elements capable of operating over a different frequency range.

[0002]

2. Description of the Prior Art When aiming at good sound reproduction, generally only attention is paid to the characteristics of the sound reproduction apparatus. The listening space has a great influence on how the music resonates, and in most cases, the listening room is the largest factor affecting the sound reproduction.

[0003]

The acoustic characteristics of the listening room are as follows:
For example improved by the use of different acoustic panels lining walls and ceilings. Such a passive method is
It is difficult to realize at frequencies below 0 Hz. To solve the problem presented by low frequencies, the device mentioned at the outset is provided, by means of which the resonance of the room is damped or eliminated. This is due to the fact that the device is capable of canceling low frequency acoustic waves. Devices located in the corners of the room can damp standing waves at said corners. Early reflections and reverberation observed at high frequencies, substantially affect the properties of the room is listening space. Devices of the type described above do not affect the properties of the space in this respect. A typical room typically has a very small early reverberation and reverberation is very sparse and has a very short duration.

[0004]

The apparatus of the present invention comprises 200
It also affects the characteristics of the room due to frequencies above Hz. The device of the present invention receives an electrical signal proportional to the sound in a room and produces a signal in response to said signal that produces an acoustic field containing early reverberation and reverberation in the room when reproduced by a loudspeaker. An environment generator configured as described above is further provided. The environment generator is the same component that receives an electrical signal proportional to the sound in the room either directly from the sound reproduction device or by a microphone contained in the device, said microphone acting as a pressure transducer in connection with the control circuit. Is highly preferred.
Therefore, it is highly preferred that the pressure transducer is a pressure sensing microphone.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a conventional circuit for active cancellation of low frequency room resonances. The circuit comprises a pressure-sensing microphone 1 arranged to provide an output to a control circuit 3, the output of the control circuit 3 being connected to a loudspeaker 2.
The pressure detection microphone 1 detects the pressure in the room at the position where the device is arranged. The control circuit 3 operates to maintain the pressure detected by the detection microphone 1 at zero pressure by generating a signal for canceling the pressure in the pressure detection microphone 1 reproduced by the loudspeaker 2. In this way a so-called acoustic throat is formed. When a positive pressure peak (acoustic wave) reaches the pressure detection microphone 1, the beam of the loudspeaker 2 moves backwards,
The pressure micro phon 1 is reduced. In this way, the device "absorbs" acoustic waves. If the device is located in a corner of the room, the elimination or damping of room resonances will occur. In fact, multiple devices like this are needed in the room,
The effective frequency range is approximately 20 to 200 Hz.

FIG. 2 shows an apparatus according to the invention for changing the acoustic properties of a room. This device according to FIG. 2 generally comprises the device of FIG. 1 as a base. In addition to this, the device comprises an environment generator 4 which provides an output to the loudspeaker 2. Therefore, the outputs of the control circuit 3 and the environment generator 4 are the points 6
Is totaled in. In the known solution of FIG. 1, a loudspeaker 2
Is a loudspeaker capable of reproducing only low frequencies. However, the loudspeaker 2 in the device according to the invention is in the audible range, i.
It must be able to reproduce the entire 0 Hz frequency band. In the device according to the invention, the environment generator 4 is arranged to receive a control signal which is proportional to the sound in the space in which the device is located and which is obtained directly from the sound reproduction device 5 or the pressure detection microphone 1.

FIG. 3 shows the acoustic waves in a room that exist when the listener 7 and the acoustic source 8 are facing each other and resting in the center of the room. In this situation, the listener 7 first receives from the acoustic source 8 the direct acoustic waves indicated by the large arrows, the early reverberations additionally indicated by the solid lines, and the reverberations indicated by the dashed lines. There must be a sufficient amount of early reverberation, and the reverberant field is sufficiently dense,
Must have sufficient duration. Music played in a room equipped with the device of the present invention sounds like the same sound as in a concert hall, for example. In a typical room there are very few early reverberations, reverberations are also very sparse and short, so that the environment generator 4 is configured to generate a signal of the kind shown for example in FIG. It
In this figure, the direct sound received by the environment generator in electrical form directly from the sound reproduction device 5 or by "listening" in the room by a microphone such as the pressure sensing microphone 1 is the time axis t. Is shown on the far left of. In response to the received signal, the environment generator 4 produces the signal in FIG. 4, shown as early reverberation and reverberation. These are the signals that correspond to the direct sound, but are appropriately delayed and attenuated.

The reverberation produced by the environment generator is preferably adapted to the room's natural reverberation so that the final result is optimal. For this reason, the environment generator is preferably able to generate a plurality of different types of signal patterns corresponding to FIG. 4, and the number of early reverberations and the power level in these patterns are the same so as to vary the level and number of reverberation signals. It changes to a degree. By adjusting the level and number of early reverberations and the level and number of reverberant signals, one significantly affects how the music resonates in the room in question.

In the foregoing description, the apparatus of the present invention has been mainly described in brief by way of one exemplary embodiment, and the described apparatus is a technical element of the invention as defined in the claims. It will be appreciated that many different types of electronic solutions can be implemented without departing from the scope.

[Brief description of drawings]

FIG. 1 is a conventional device for damping resonance of a particular low frequency room.

FIG. 2 shows a device according to the invention for changing the acoustic properties of a room.

FIG. 3 is a diagram showing a room having acoustic waves.

FIG. 4 shows the signal generated by the environment generator of the device of the invention on a time power scale.

[Explanation of symbols]

1 ... Pressure transducer, 2 ... Loudspeaker, 3 ... Electronic control circuit, 4 ...
Environmental generator.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Aki Mekibata S.F.-33720 Tampere, Nathalie Yungcatu 27 H 30 (56) References JP-A 4-2928 (JP, A) JP-A 2-150197 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G10K 15/00 G10K 11/178

Claims (3)

(57) [Claims] 1. A pressure transducer, an electronic control circuit, an environment generator,
A device for changing the acoustic characteristics of a room equipped with a loudspeaker
The pressure transducer generates an electric signal according to the pressure change in the room.
The electronic control circuit, in response to the electrical signal from the pressure transducer,
Emits an electrical signal that acts to offset the pressure change in the room
The environmental generator is a power source from a pressure transducer or sound generator.
An electrical signal containing early reverberation and reverberation depending on the air signal
The loudspeaker generates electrical signals for electronic control circuits and environmental generators.
A device that changes the acoustic characteristics of the room being played. 2. The pressure transducer is a pressure detection microphone.
An apparatus for changing the acoustic characteristics of a room according to claim 1. 3. The loudspeaker is capable of reproducing the entire audible frequency range.
The acoustic characteristic of the room according to any one of claims 1 and 2.
A device that changes.