close

Вход

Забыли?

вход по аккаунту

?

JPH06269078

код для вставкиСкачать
Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH06269078
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates mainly
to the interior of a room using a directional loudspeaker system.
[0002]
2. Description of the Related Art Conventionally, horn speakers, reflective speakers, parametric
speakers, and array speakers are known as directional speaker systems. Therefore, a
conventional directional speaker and its characteristics will be described by taking an array
speaker as an example.
[0003]
(FIG. 7) shows an example of the arrangement of the speaker unit of the conventional array
speaker. An array speaker 1 is configured by arranging 12 speaker units 2 in a cross shape with
a pitch of 25 cm.
[0004]
03-05-2019
1
(FIG. 8) shows the use of the array speaker 1. The array speaker 1 is attached to a ceiling surface
3 m high, and the listening position of the listener 3 moves on a horizontal surface 1.5 m away
from the speaker The case is shown. The measurement results of the sound pressure level
distribution in the horizontal plane 4 including the listening position are shown in FIG. However,
FIG. 9 shows the case where the sound absorption coefficient of the floor is 1 (anechoic chamber
characteristics), FIG. 9 (a) shows the case of 1 kHz, and FIG. 9 (b) shows the case of 500 Hz. The
interval between equal sound pressure lines is 3 dB. Also, FIG. 10 shows the case where the floor
is reflective (the sound absorption coefficient is about 0.1). As is clear from (Fig. 9) (Fig. 10),
while the anechoic chamber characteristic shows a sharp directivity as the theory almost, in the
case of a reflective floor, the directivity is significantly degraded . This is because the high level
sound waves reflected on the floor diffuse into the room.
[0005]
It has been known in the prior art that it is necessary to make the interior as sound absorbing as
possible in rooms using directional loudspeakers. As described in the conventional example, even
if the array speaker itself has a sharp directional characteristic, if the sound absorbing property
of the room using it is insufficient, the directivity is lost and it is not practical. However,
conventionally, there has been no report on the place to be made sound absorbing or the
required sound absorption coefficient etc. in detail.
[0006]
The present invention was made as a result of conducting detailed experiments on these in order
to solve the above-mentioned problems, and it is an object of the present invention to obtain
sharp directivity even when used in a sounding room.
[0007]
In order to achieve the above object, a directional speaker system according to the present
invention comprises a directional speaker and a sound absorbing surface provided on the
opposite surface of the directional speaker, and the sound absorption The sound absorption
surface is provided on the inner side of an equal sound pressure line which has an average sound
absorption coefficient of at least 0.7 or more and which is attenuated by at least 6 dB from the
highest sound pressure level on the opposite surface of the directional speaker. Do.
[0008]
03-05-2019
2
According to the above configuration, the direct wave emitted from the directional speaker is
incident on the sound absorbing surface provided on the opposite surface, and 70% or more of
the sound is absorbed here.
Therefore, by the time the primary reflected sound reaches the listener's ear again, it attenuates
by at least 5 dB or more with respect to the direct wave without considering diffusion, and in fact
it also attenuates by 10 dB or more because diffusion and distance attenuation are also added.
Also, the level of indirect sound after the secondary reflection sound naturally attenuates further.
[0009]
On the other hand, it is known from the result of the intelligibility test and the like that the sound
from at least the adjacent speaker needs to be attenuated by at least 10 dB so that the sound
from the adjacent directional speaker can be clearly heard without being bothered. ing.
According to the configuration of the present invention, it is possible to clearly hear the sound of
each speaker without impairing the performance of the directional speaker.
[0010]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present
invention will be described below based on FIG. In FIG. 1, reference numeral 1 denotes an array
speaker described in the prior art. 5 is a sound absorbing material provided on the floor, and is
provided in a range of 3 m square around the front of the speaker. The structure of the sound
absorbing material is shown in FIG. FIG. 2 (a) shows the structure of the sound absorbing
material according to the first embodiment. In the figure, reference numeral 6 denotes a
perforated plate, which constitutes a resonance type sound absorbing body 8 from an air layer 7
provided on the back surface. A carpet 9 of 12 mm in thickness is laid on the surface of the
resonance type sound absorber 8. The sound absorption coefficient frequency characteristics of
the sound absorbing material of this example are shown in a of FIG. 3, and it can be seen that an
average sound absorption coefficient of 70% or more is obtained in the band of 200 Hz to 5 kHz.
Also, the sound pressure level distribution in the horizontal plane is shown in FIG. The same
figure (a) shows the case of 500 Hz in the case of 1 kHz. The interval between equal sound
03-05-2019
3
pressure lines is 3 dB. By absorbing the primary reflected sound, even at 500Hz, it was
attenuated by 10 dB or more if 2m away from the front of the speaker, and it was possible to
clearly hear each other even when the two directional speakers were installed 2m apart.
[0011]
FIG. 2 (b) shows the structure of the sound absorbing material according to the second
embodiment. As shown in the figure, a 50 mm thick urethane foam 10 is provided on the surface
of the perforated plate 6 instead of the carpet, and a perforated iron plate 11 which does not
interfere with sound transmission for walking is laid on the surface. It has a structure. The sound
absorption coefficient frequency characteristics in this case are shown in b of FIG. 3 and the
sound pressure level distribution in the horizontal plane is shown in FIG. In FIG. 5, (a) shows the
case of 1 kHz, and (b) shows the case of 500 Hz, and the interval between contour lines is 3 dB.
As apparent from (a) in FIG. 3, an average sound absorption coefficient of 90% or more is
obtained in the band of 200 Hz to 5 kHz. Further, in this case, it can be seen that sharp
directivity is obtained with almost no loss in the performance of the array speaker shown in FIG.
[0012]
On the other hand, in the conventional sound absorption process for laying a carpet, the sound
absorption coefficient was only about 0.3 even at 1 kHz, and there was almost no difference from
the case of a reflective floor in the bass region such as the voice band.
[0013]
Next, as a result of investigating the relationship between the area of the sound absorbing
surface and the directivity, in the frequency band requiring directivity control, the point on the
front axis of the speaker, ie, the point with the highest average sound pressure level (FIG. As
shown in 12), it was found that the target performance can be achieved by placing a sound
absorbing material inside the isoacoustic line that attenuates by at least 6 dB on average.
However, this range changes with frequency and becomes wider as the directivity becomes
wider, so preferably at least 6 dB at the lower limit frequency (for example, 400 Hz for voice) of
the band requiring directivity control. A sound absorbing surface may be provided inside the
equal sound pressure line to be attenuated.
03-05-2019
4
[0014]
Of course, the type of directional speaker and the configuration of the sound absorbing surface
are not limited to those of this embodiment. Further, in the present embodiment, since the
directional speaker is installed on the ceiling, the sound absorbing surface is provided on the
floor which is the opposite surface, but in addition to this, for example, when the directional
speaker is installed on the wall surface Needless to say, it may be a sound absorbing surface.
Furthermore, as shown in (Fig. 6), the isoacoustic line range 12 that attenuates by 6 dB is only
the floor surface that is the opposite surface because the directional speaker is installed near the
wall surface, the directivity is wide, etc. In the case of extending to a wall surface, it is necessary
to provide a sound absorbing surface also on the corresponding portion of the wall surface.
[0015]
The directional speaker system according to the present invention comprises a directional
speaker and a sound absorbing surface provided on the opposite surface of the directional
speaker, and the average sound absorption coefficient of the sound absorbing surface is 0.7 or
more. Thus, it is possible to obtain sharp directivity without losing the performance of the
directional speaker even in the sounding room.
03-05-2019
5
Документ
Категория
Без категории
Просмотров
0
Размер файла
13 Кб
Теги
jph06269078
1/--страниц
Пожаловаться на содержимое документа