Technology

[评论]Sound insulation technology for road audio. I try to use SHIZUKA Panel –AV Watch

Improving room acoustics has been a long-standing problem for audiophiles. In the housing situation in Japan, there are countless problems such as limited volume that can be exported, left-right asymmetry, softness of floors/walls/ceilings, etc.

Audio fans aren’t the only ones suffering from room acoustic problems. Today, live distribution over the Internet and videoconferencing has become familiar. It’s not uncommon for it to be difficult to convey, as the sound echoes and lacks clarity when delivered in a typical living room. Unwanted sounds are the enemy of accurate speech transmission.

In this case, can anyone remodel the room and create a dedicated listening room or studio? Soundproofing is expensive and the room will be small, so no big deal. In this case, a room adjustment program can help. Depending on the application, there are various items such as sound absorption, diffusion, sound insulation, etc., but in this article, we will focus on sound absorbing materials.

Meet the SHIZUKA panel

Have you heard of an acoustic panel called SHIZUKA Panel? The official name “SHIZUKA Stillness Panel” is a sound-absorbing panel manufactured and sold by Seika. Shizushina is a manufacturer and distributor of sound absorbing and thermal insulation materials, established in 2006, with a proven track record mainly in industrial noise control measures such as sound insulation for highways and noise reduction for transportation equipment such as Shinkansen …

In 2012, famous engineer Seigen Ono and others joined and started product development of SHIZUKA Stillness Panel, which adopts Seika’s patented structure of sound-absorbing and sound-insulating material. In a TV show produced in the same year, Mr. Ono visited a Seika factory.

A three-layer panel that allows sound to enter from a 0.01mm grid with virtually no reflections and converts sound into heat. While it can only handle a limited range of frequencies on its own, it features the ability to absorb a wide range of sound by providing a sound-absorbing layer of different materials behind it.

The mechanism that the sound enters from the 0.01 mm mesh part with almost no reflection and converts the sound into heat energy. While it can only handle a limited range of frequencies on its own, it features the ability to absorb a wide range of sound by providing a sound-absorbing layer of different materials behind it.

The sound-absorbing material inside has a fine air layer, which will not miss the sound that has entered inside. Since the back plate also acts as a reflection, measures can be taken to prevent sound absorption and reflections.

Originally, it was 1 x 1 m in size and had no mounting legs, so users were limited to mastering engineers. The surface is aluminum, and it’s heavy and some say “hard to use”, so there’s a limit to where it can be used.

Around 2015, the panel was released in a 50 x 50 cm size, and the case was increasingly adopted by composers and mixing engineers working on the desktop. The current “B-500” and “B-1000” series went on sale from this time. From 2018, “SHIZUKA Stillness Panel SDM” whose surface has been changed to non-woven fabric has also been released. It is portable, self-supporting, foldable, and more convenient to use, and is increasingly being used at home.

B-500 Black

B-500 Silver

Wada Takafumi of Beagle Kick, the composer’s music unit, introduced it to his private studio. It appears that the introduction on YouTube also had a big impact. Until now, there are not many suitable sound-absorbing materials produced in Japan, and even the large online shopping company Sound House sells many products imported from overseas. A domestic brand of sound-absorbing panels, and a company that has no contact with the music industry appeared there, so the initial impact should be quite good. Coupled with sickness, there are more and more opportunities to record instruments and vocals at home, and it is said that the usage scene of the SHIZUKA Stillness Panel has expanded not only to professional engineers, but also to amateurs.

I was concerned because a close person introduced it enthusiastically, but I didn’t want to hear about it for months until I actually tried it myself. I experienced the SHIZUKA Stillness Panel at Inter BEE 2021 at Makuhari Messe last year. Seika is showing a booth.

Inside the booth is a listening room where you can experience surround sound, with panels covering the walls and ceiling. What surprised me in particular was the use of the SDM-1800 in this exhibition, which can be called a “quiet experience”. I’m sorry for the out-of-focus photos I took with my smartphone, but as you can see, there’s enough room for one person in the middle of multiple SDM-1800s.

I took a deep breath as I put my body in. The hustle and bustle of Makuhari Messe immediately dissipated, as if in a simple soundproof booth. When I was surprised and tried to get out of the SDM-1800, the noise of the venue came back. I retyped it a few times to confirm it wasn’t an ear illusion, but no doubt about it. I think the hustle and bustle of the exhibition hall is quite noisy above the municipal level in the local city. Not completely inaudible, but suddenly so quiet that it felt like there was a room in the middle. It’s an experience of literally doubting your ears.

Even in the low frequency range where sound insulation is difficult, there is a loss of more than 20dB, and there is a loss of more than 30dB in the middle and high frequencies. Speaking of 30dB, it is already close to the performance of wooden soundproof doors (just look at the value).

I firmly believe that a simple recording studio, once introduced into an ordinary home, can be easily built. Live distribution such as live games will be able to achieve proper sound absorption and sound insulation at the same time. It will be possible to deliver a clear and professional sound to the other party.

Amazed writers greet the staff with irresistible arrows and shields. Later, I went to the factory of Ebina Headquarters to talk with him, and cooperated with him to trial-produce the demo machine. I’d like to experience it as an audio writer, but I’d like to confirm its true capabilities as a sound absorbing candidate in my home soundproofed studio and recording studio.

try using it at home

However, since things are things, they cannot be used on a large scale. This time, two pieces of “B-500-1” (with feet/tax excluded: black 29,000 yen, silver 26,000 yen) are made of aluminum fiber composite material for sound absorption and aluminum plate for sound insulation. I borrowed a “SDM-900” (tax excluded: 50,000 yen) whose sound-absorbing surface is polyester, the sound-absorbing surface is PVC, and the surface material is non-woven fabric.

The B-500-1 has a slim profile with an external dimension of 505 x 505 mm, a thickness of 36 mm and a weight of 2 kg. The SDM-900 consists of two panels, 900mm high and 450mm wide, 43mm thick when folded and 85mm thick when folded. It weighs 5.3 kg and is light enough to carry anywhere.

The above SDM-1800 is a large size with a height of 1,800 mm. As for the B-500, there is also a model “B-500-2”, which has no legs, only panels.

The audition took place in three places: asymmetrical living room-dining room kitchen with about 14 tatami mats, soundproof studio with less than 6 tatami mats, and recording studio with less than 2 tatami mats. What is the audio review, the measurement and other data are not been acquired.

The appropriate use and quantity (number of sheets) of room adjustment items vary greatly depending on the room used and the desired effect. There are as many optimal solutions as there are circumstances and purposes, and we would appreciate if you could use them as a reference.

Before proceeding with the audition, let me explain my living-dining-kitchen acoustics.

In short, the different volume of space left and right of an audio system can cause acoustic problems. Specifically, the silk curtain is about 60 cm away from the left speaker, while the right speaker is about 150 cm away from a wall, behind which is the kitchen space.

Originally, the speaker is best installed in the center of the installation surface (wall, etc.), symmetrical, including the structure of the room and the arrangement of furniture. However, in my living room, the volume in the left and right spaces is different from that of the speakers, and there is an imbalance in sound propagation and reflection. As a result, the sound image is diffused, the sound field is unclear, and the localization focus is loose.

I tried the sound absorbing panels of each product. First, try two B-500-1 cards. I decided to put it in an area with more space to the right of the speaker. He expects the left-right imbalance to be alleviated primarily by absorbing direct sound from the right speaker. I also changed the detailed installation location. As shown in the photo, the pattern placed in the direction of the sound propagation and the pattern placed straight in the sense of symmetry with the left wall. The latter also compares the speaker unit aimed directly and slightly tilted.

Patterns placed in the direction the sound travels

The pattern is placed straight, taking into account the symmetry with the left wall.Aim directly at the speaker unit

The pattern is placed straight, taking into account the symmetry with the left wall.slightly slanted version

The result of the comparison is that, compared to the “Awareness mode of sound propagation direction”, the “directly aimed at the speaker unit mode” has a more unified perception of the left and right sound field and sound image. Maybe the same distance from the left curtain (about 60 cm) can have a positive effect. In the author’s room, it is better to decide the installation position for “balanced left and right sound environment” rather than “sound absorption”.

good location

The audition source was Beagle Kick’s “Rememberance,” recorded in the lobby with a single DSD. A jazz quartet recorded in a small shoebox-style hall, mainly mixed with stage mics (2ch), supplemented by four on-mics. This song, which I also participated in the recording, was produced with attention to detail, including the mixing.

If two B-500-1s are placed, the extravagant flesh attached to the sound image of the electric guitar or drum heard from the right will fall off and the details will be clearly visible. I think the piano is also a bit sharper from the left side. Since it is a hall, the recorded sound is a bit lively, naturally, but before the panel is installed, there is a one-to-one unpleasant sound. In short, it’s not the entire tone recorded in the source, but the dramatization of the room sound is not needed.

The sound of the stage mic and the sound of the mic are distinctly separate, and I’m surprised they can be heard as an image. It’s also a good impression that you don’t feel the peaks and troughs that create discomfort in the sound-absorbing frequency band. The reverberation in the hall is clean and rich in layers, which is very close to the atmosphere of the scene. This change can be achieved by simply placing two thin sound-absorbing panels in the living room, i.e. 14 tatami mats including the kitchen area. The effect is better than expected.

As for how to set the angle of the speaker unit, aligning the unit with the unit has the effect of making the instrument sound clearer, but on the other hand, I felt discomfort in the soundstage on the right side. Maybe it works well with the speakers. The way sound travels from the unit has a lot to do with speaker design. It’s a good idea to find the best while doing fine-tuning.

Try the SDM-900

Next, I installed an SDM-900. Since there is only one speaker this time, I compared three modes: when close to the speaker, in the middle, and apart. Based on the previous results, the distance to the right of the speaker is set to 60 cm.

Install an SDM-900

Install close to the speaker

It’s obviously unnatural when you’re close to the speakers. Both the left and right sound fields became distorted, probably because the sound was being absorbed too much directly.

speaker installation

Conversely, if it is too far from the speakers, the balance and front-to-rear feel of the left and right sound fields will be disrupted, and the sound heard from the right side will become blocked, making it no longer a place to listen to music. Sound-absorbing panels that are too close to the listening point seem counterproductive.

installed in the middle

To reduce initial reflections on the kitchen side = absorb sound, stand in the middle to balance left and right.

Effects vary widely based on location, so it’s best to try various locations to find the best one. I don’t mind the B-500-1, but unfortunately the mids and highs are mixed for every taste. I felt harsh distortion and side effects like dirt. This seems to be affected because the surface of SDM-900 is non-woven (chemical fiber). It is said that synthetic fibers may produce unique peaks because the fiber orientation is uniform.

On the other hand, the texture of the natural material is hardly deteriorated. In my experience, wool has better acoustic properties than cotton, and silk has better acoustic properties than wool. In particular, the effect of silk as a tuning material is huge, not only does not produce unique peaks, but also organically enhances the texture. Even a thin cloth like tulle works great.

In addition to the SDM-900, try placing the B-500-1 behind the listening point. In the living room, I usually have a table and a cushion, so I put one of each at the diagonal back of the cushion.

The additional reverberation is reduced, the sound image is not spread, and the change is dramatic, as if the hearing is focused on the direct sound of the instrument played by the performer in the concert venue. The tone of the hall becomes more airy, and the size of the space and the height of the ceiling are conveyed authentically. I feel like I can recreate that impression I recorded in the living room hall.

As a bonus version, I’m trying to block the access to the kitchen and kitchen counter with the B-500-1. The SDM-900 has been removed. The conclusion is that there is no effect. No improvement. If you accidentally move the mounting point too far from the speakers, it seems like you’re far from solving the problem. If you’re looking to add more panels to your best install yet, that might be an ant. Of course, the panel cannot be placed in such a place in reality.

Try installing it in a soundproof studio

Next, try it in a soundproofed studio where you don’t have much to complain about room acoustics. The ceiling is low, and the area is slightly smaller than 6 tatami due to sound insulation work, but the structure of the room is symmetrical, making it a more ideal acoustic space than the living room.

The SDM-900 mounts directly behind the listening point.

I felt the positioning became clear, but the ceiling height became ambiguous. The sound image is of course sharp. However, I’m still concerned about the dirt on the mid to high end textures mentioned above.

I installed the B-500-1s one by one in the back.

Install the B-500-1 one by one directly behind

The positioning is clear and the sound image is sharp as well. However, I like the way the sound is absorbed naturally, or the feeling that it doesn’t destroy the mood of the original sound. While the energy and core of the instrument sound is solidly highlighted, additional reverberation in the room is reduced, and the musician’s hall performance can be easily focused. The B-500 series was developed to “create an accurate monitoring environment”, so it might be to my taste.

Not only did I listen to the jazz recorded in the hall, but also the anime songs of many voices. The separation is better and each part is easier to hear. Instruments such as vocals and bass centered on the center are taut, enhancing the dynamic. I think a song with a lot of notes and a fast tempo has a better sense of movement. It sounded like I fell asleep before putting the panel down. I’m surprised the transients are so blurry due to the echoes. When I designed this room, I was using it for a home studio, but I wanted to enjoy movies and music comfortably, so I asked him to design it so that it resonated in some way. I don’t regret it, but I’m acutely aware that the idea of ​​sound absorption may have room for reconsideration.

Finally, try using it in a recording studio that comes with a soundproof studio. It is less than 2 tatami in size, with woolen carpet on the floor and alternative sound absorbing material on most of the walls to eliminate unwanted reverberation. It’s a room dedicated to recording narration and dialogue, so it’s a bit lifeless, but nothing is glued to the soundproof door. Compared to the so-called professional narration studio, it still sounds good. The performers could relax a bit by not being too dead, but I wonder if I should absorb more of the sound.

Install the SDM-900 near the door.

Install the SDM-900 near the door

Due to sound absorption, the proportion of direct sound is higher than that of echoes, so it is easy to concentrate on the content of the sound. The details of the sound are also drawn more clearly. The influence of mid-high frequency odor is less than that of listening to music. It’s only understandable compared to pre-installation.

This time, I had a B-500-1 at the door, but it was almost the same as when there was nothing.

When I put the other one on the opposite side of the door, near the dryer, I can record the contours of the sound as clearly as the SDM-900.

I think there is a core to the sound and I like the sound absorbing properties.

By the way, are sound-absorbing panels effective against standing waves? In my apartment, there is a square bedroom, and when I clap my hands in that room, there is an unpleasant noise. I tried placing each panel here and there, but it backfired just by adding unpleasant reverb. A square room (determined precisely by the ratio of “front:depth:ceiling height”) is prone to standing wave deviations that can lead to unpleasant sounds, but it is the basis for acoustic panels and diffusers. Note that it will not be a countermeasure.

Experience great sound absorption despite being thin and compact

Although the SHIZUKA Stillness Panel is thin and portable, I was able to realize that it has excellent sound absorption properties. Absorption frequencies have no local peaks or troughs and are also suitable for listening to music and monitoring. If you want to build a simple recording (quiet) studio, don’t miss the SDM-1800 with a height of 1800mm.

Personally, I think the stylish design is also attractive. The current distribution channel is expanding to Rock oN Company, ikebe musical instrument stores, sound houses and sound unions, but it’s a project that those who know it still know. However, well-known studios such as Onkio Haus, OTTAVA and Sidera Mastering are listed as introductory results for commercial use.

For audio rooms, those who want to mitigate the effects of an asymmetrical room in some way. There are very few things in the room that absorb sound, and it is suitable for people who are uncomfortable because the sound reverberates too much.

The person recording or broadcasting wants to properly absorb the sound and provide a clear sound (recording). It is suitable for those who wish to create a quiet environment locally by isolating the faint living sounds and noises from next door and outside.

Creating a room is one of the important factors in determining audio quality. It’s fun to put your passion into improving the direct sound of your speakers, but consider upgrading your room’s acoustics as well.

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