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2021-03-10

How to efficiently improve sound absorption in an audio recording room (Part 2)

Hello, this is Mr.I of Shizuka Co., Ltd..

Today’s article is a continuation of the previous article “How to efficiently improve sound absorption in an audio recording room (Part 1)”.

Notation of sound absorption performance data

Now, please be careful how you describe the sound absorption performance data.

For example, I have seen some data stating that even though the material is thin (1~10mm thick), it can absorb sound from low frequency (below 100Hz) to high frequency. If the material is really 10mm thick and absorbs all sound ranges, it would be easy to use, but there is a way to tell the truth.

In fact, in many cases, such data takes the “air layer at the back”. The air layer is often measured between 50mm and 100mm, so even if a 10mm thick sound-absorbing material is used, it will not be effective unless an air layer of 50-100mm is provided behind it.

If a space of 50 to 100 mm is provided, even the sound absorption coefficient of a fiber material like rock wool can absorb low frequencies. In the design of a concert hall, the reverberation time (sound resonance) of the room volume is checked, and the necessary materials and installation area are calculated based on the above sound absorption coefficient. Therefore, if you can understand the sound absorption coefficient data, it will help you to reduce the cost and installation area.

Combination of materials to absorb

With current research, it is possible to combine even already existing materials to achieve better performance than calculated. Therefore, if you install some sound-absorbing material on top of the purchased sound-absorbing material, it may absorb a wide range of sound frequencies.

The orthodox combination is to use 1-10mm felt-like fiber material on the surface, 10-50mm sound-absorbing material (glass wool, rock wool, etc.) inside, and a board (not necessary, 1-5mm thick) for fixing to the wall on the back. With this method, it is possible to absorb sound at 500Hz or higher.

For sound absorption in the middle and high frequency range, it is possible to achieve an effect by changing the thickness of the material, but there are not many effective products for low frequency sound absorption.

It is possible to improve the sound absorption performance in the low frequency range by increasing the thickness of the sound-absorbing material, but it is known that no matter how thick the urethane is, there is almost no sound absorption in the low frequency range.

For sound absorption in the low frequency range, it is said to be effective to attach a material that receives vibrations to the surface of the sound-absorbing material to catch and alleviate the low frequency sound, and then absorb it with the sound-absorbing layer inside. In fact, this method has been used as a noise countermeasure for industrial machinery (factories).

However, there are an infinite number of combinations of materials that can receive and absorb vibrations, so more research and development is still needed (there are panels that can absorb and block bass noise from construction work, but they are more than 200mm thick and weigh 50kg/m2, so many of them are not suitable for indoor use).

Sound absorption in audio rooms

For audio rooms, we recommend placing our “SHIZUKA Stillness Panel SDM” on the back of the panel. “SDM” has a wide range of sound absorption (500-4000 Hz and above), so it is recommended for those who want to hear the exact reproduction capability of audio.

If you want to enjoy the flavor of the audio sound, we recommend placing it in the corner of the room, near a window, or on your own back, not on the back of the audio system. This will remove unwanted echoes and allow you to hear the true flavor of the audio. Since the product can be folded, it can also be installed as a retrofit. Even if you already have an audio room, you can use this product according to the sound you want to reproduce.

Example of SDM installation. Two black SDMs are installed on the back of the audio system.
Example of audio installation. 1 SDM blue. Reduces echoes from windows.

In a recording room, you can place it around your speakers, monitors, or on your back to help you distinguish the sound accurately.

For large studios, “SDM” can be combined to create a simple recording booth. When installed around a microphone, it can remove unwanted flutter echoes and make recording possible. In addition, it is portable, which is useful when you need to record outside the studio.

“SDM” is currently sold by dealers in Japan, but it is also available for free rental, so if you would like to borrow it, please contact us from the “Contact Us” page.
*Currently only available in Japan.

We are also working on the development of sound-absorbing products, so please feel free to contact us if you have any questions or comments.

A simple booth was set up by combining “SDM”. Microphone sound can be recorded.
Can be carried in a bag.


神奈川県厚木市金田492-1