主题：各位老师您们好！我想设计一间9平方的小消音室，请各位多多指教。

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看一下音箱的模拟,都没障板的.供参考!

附加说明一下:箱体容积20升,闭箱,单元为FOCAL 27KX 1W模拟

Half-space or pit measurements are made by recessing the loudspeaker in the
ground with the drivers facing toward the sky, and the microphone placed
above the enclosure. Again, the mic should be directly in line above the high
frequency driver. This is shown in the figure below.
Since this type of measurement places the baffle board of the enclosure in an
infinitely large plane, measurements made in half-space do not exhibit the
rising response that occurs with anechoic or ground plane measurements.
However like the ground-plane, the radiation field is half of a full sphere so the
level is 6dB higher than a free field or anechoic measurement.
As with ground plane measurements, there should be no obstructions for a 15-
30 foot radius around the area for low frequency work.
Pit measurements can be one of the very best for producing SPL response
curves of the transducer/enclosure free of any reflection defects caused by the
environment. Many loudspeaker researchers and manufacturers have employed
this method for years.
In some cases the size of the plane can be reduced. If mid and high frequency
response plots are required, a smaller plane is permissible. A plywood table 8
feet square with a hole cut in the center for the transducer would provide good
results down to about 200Hz. The table can be above the floor and will act as
an infinite plane at these frequencies.

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Anechoic measurements require either a specially constructed anechoic chamber,
or placement of the speaker in mid-air far from any surfaces. The only
surface is that of the baffle board of the enclosure. This method includes the
enclosure diffraction effects.
The purpose of an anechoic chamber is to absorb all sound striking the walls
so that none is reflected. This is typically handled by covering the walls of a
room with sound absorbing materials. A chamber is shown below.
However, even well designed chambers still do not approach the ideal anechoic
behavior at low frequencies. At low frequencies, total absorption is extremely
difficult to achieve. For this reason most chambers degenerate to the behavior
of a constant pressure enclosure as frequency is decreased.
At these frequencies the pressure field will cause a rise in level with decreasing
frequency typically 12dB/Octave. In the mid and high frequencies the
chamber will usually have good anechoic characteristics.
Given the difficulty of either building an anechoic chamber or dealing with
microphones and loudspeakers suspended high in mid-air, true anechoic
measurements are not convenient for most people.

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Ground plane measurements are very nearly identical to anechoic measurements.
Because the measurement includes both the direct sound from the enclosure, plus
the mirrored image from the ground plane, the SPL for the same microphone
placement distance will be 6dB higher than the anechoic SPL level.
The only requirement for a ground-plane measurement is a large reflective surface,
such as a parking lot or drive-way, with no obstructions for a radius of 20-30 feet
or more. The procedure is to place the loudspeaker on its side on the ground, and
then place the microphone on the ground in front of the speaker.
Ground plane measurements, like anechoic measurements, will have a rising
character in the response caused by diffraction off the loudspeaker baffle board.
This occurs in the mid range region. The increase in SPL is about 6dB, the frequency
being determined by the total area of the baffle.
If you are measuring a multi-way enclosure with low, mid, and high frequency
drivers, the enclosure should be positioned on its side with the high frequency driver
nearest the ground. The microphone should be aligned on axis with the high
frequency driver as well. The off-axis angle relative to the wavelengths of the mid
and low frequency drivers will typically not be significant.
Many times it is a good idea to slightly tilt the enclosure downward toward the
microphone. The important goal here is to try to keep the microphone on-axis with
the high frequency driver.
The ground plane method is a very good choice and does not require any expensive
or elaborate set up. All that is required is a flat surface with some open area around
it. See the figure below.

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