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Spring-Loaded Screw Turns Drywall Into Sound-Absorbing Panels

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  • Spring-Loaded Screw Turns Drywall Into Sound-Absorbing Panels

    https://gizmodo.com/new-spring-loade...orb-1847280616

    0b12d870d336e8de4b48f8a4a4ce857d.jpg
    The smooth featureless walls around your home are easy to paint and great for hanging artwork, but they’re also very effective at transmitting soundwaves from room to room—a less desired feature. Adding soundproofing is one solution, but a cheaper and easier way is to install drywall using these clever spring-loaded, sound-damping screws instead.

    When attaching sheets of drywall to the wooden framed walls or ceiling of a room, special screws with a deeper thread are used to ensure the panels never come loose. But while the walls of your home might feel strong, drywall is actually quite flexible and can function like a drumhead, vibrating when sound waves hit it and then transmitting those sounds. If you’ve ever lived in an apartment and had no trouble hearing your neighbors’ arguments, you’ve experienced the downside of the material that mostly replaced plaster walls decades ago.

    There are many solutions to preventing sounds from escaping a room. Insulation blown into the walls will help absorb soundwaves, and garages typically use thicker sheets of drywall that are better at absorbing sounds. You can even cover the walls in sound-absorbing panels with angled features that dissipate a sound wave’s energy—a solution often used in recording studios—but that can be both expensive and unsightly. The Sound Screw, developed by Håkan Wernersson of the Department of Materials Science and Applied Mathematics at Sweden’s Malmö University, is a more streamlined solution that requires no custom installation tools.

    Whereas a traditional drywall screw holds a panel of drywall snug against the wooden studs that make up the structure of a room, the Sound Screw features a flexible spring just below the head. It still holds a piece of drywall securely against a wall, but with a very slight gap allowing the spring to expand and compress, damping the energy of soundwaves hitting the walls making them much quieter as they reverberate into another room. During testing in a sound lab, researchers say, the use of the Sound Screws was found to reduce sound transmission by up to nine decibels, making the sounds bouncing into a neighboring room about half as loud to human ears.

    The creator of the Sound Screw is still looking for manufacturers to put their creation into mass production. And while its design means it will be more complicated to make and, in turn, more expensive than standard drywall screws to purchase, in the long run, it should be a more economical alternative to other sound-proofing methods, particularly when it comes to how easy these are to install. If you can use a drill or a screwdriver, you already have all the expertise you need.

  • #2
    There is also "resilient" channel that also spaces drywall off of the studs.

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    • #3
      Well, Resilient channel is not actually very effective at stopping sound either and is not recommended for anything other than light residential use. Below is a link to an in depth article as to why... It's going to be pretty difficult to beat the high isolation that staggered stud walls offer. I had a customer in Wisconsin back in the 80's that tried double cinder block walls and that was also a failure. Cinder block is way to porous. Because they found out after the fact, they would have had to remove all the surrounds and sound-fold in order to seal the walls. Anyway, they never used that architect again. That theater was right next to the Wisconsin River and it flooded twice and was written off. As far as those screws go, I would want to see some hard data and wall designs first.

      https://www.soundproofingcompany.com...ilient-channel
      Last edited by Mark Gulbrandsen; 07-14-2021, 09:32 PM.

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      • #4
        Resilient channel's purpose is to keep the drywall from being a conveyance to the studs. It is not a cure all for all sound anymore than that spring screw will be. Sound travels through solids better than air...as any mechanic knows as they use a screwdriver as a stethoscope for hearing mechanical noise. Having the walls essentially float is a first line of defense. So is cutting the slab between rooms (the floor will carry the sound too, as will the ceiling and a common wall behind the screens). Building an STC-75 wall is an undertaking. It generally involves layers and asymmetry to achieve such ratings. I can't tell you how many theatres seem to avoid putting fiberglass above the ceiling tiles. If they did, it would help with sound transfer, really help with RT-60 and it would even help on HVAC to not heat/cool the space above the ceiling tiles.

        Dual wall staggered stud with fiberglass can do...okay but it is no ball of fire either. It won't get you into the STC 70s either so bass WILL be coming through, to some extent. Stopping the high frequencies isn't the tricky part, it is the bass frequencies because those long waves will cut through most wall systems like butter. Some time ago, we were asked to measure a wall system where a special wall system was installed to stop sound transfer over top of the existing system. It certainly improved things but it wasn't the end all. We measured FSTC-60 - FSTC-62 (we measured several theatres. :


        Screen Shot 2021-07-14 at 11.34.49 PM.png

        Being down 38dB at 125Hz is great but you can see that by the time you are in subwoofer territory (20-80Hz), it is going to be closer to just 25dB. STC doesn't go down below 125Hz. In fact, we did measure down to 31.5Hz:

        Screen Shot 2021-07-14 at 11.40.54 PM.png
        The red lines are where you'd like to be to avoid hearing the other theatre, the violet lines are where they were. This is pretty typical of what I see in most theatres.

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        • #5
          Originally posted by Steve Guttag View Post
          Resilient channel's purpose is to keep the drywall from being a conveyance to the studs. It is not a cure all for all sound anymore than that spring screw will be. Sound travels through solids better than air...as any mechanic knows as they use a screwdriver as a stethoscope for hearing mechanical noise. Having the walls essentially float is a first line of defense. So is cutting the slab between rooms (the floor will carry the sound too, as will the ceiling and a common wall behind the screens). Building an STC-75 wall is an undertaking. It generally involves layers and asymmetry to achieve such ratings. I can't tell you how many theatres seem to avoid putting fiberglass above the ceiling tiles. If they did, it would help with sound transfer, really help with RT-60 and it would even help on HVAC to not heat/cool the space above the ceiling tiles.

          Dual wall staggered stud with fiberglass can do...okay but it is no ball of fire either. It won't get you into the STC 70s either so bass WILL be coming through, to some extent. Stopping the high frequencies isn't the tricky part, it is the bass frequencies because those long waves will cut through most wall systems like butter. Some time ago, we were asked to measure a wall system where a special wall system was installed to stop sound transfer over top of the existing system. It certainly improved things but it wasn't the end all. We measured FSTC-60 - FSTC-62 (we measured several theatres. :
          .

          However, the resilient channels are still attached to both the studs and the dry wall, hopefully!! And there is simply no way around that no matter what. And.. if you want to waste more money. They also offer rubber pads to place where the channel attaches, but they only recommend using them on one side of the channel and how many years before those rubber pads disintegrate?. Then you have that darn screw in the way helping noise make it on through, but the Screw Frank is talking about above might just save all that..

          BTW, The STC ratings only go to 65, which in itself is almost impossible to attain without actually having separate rooms, each built independently of each other. That's what they did at Skywalker Sound for the Foley stages. if you are building STC 75 walls, then you should be rewriting the books on acoustics and not eating popcorn while you are on Film-Tech.. My customer's for the most part ended up doing staggered studs, two layers of 5/8 on one side and either one or three layers on the other side. You never want to use two and two because one side of the wall will tend to oscillate sympathetically with the other, and pass more sound. Even / Odd layers tend to cancel noise better. Once they mlearned the hard way, my customers also did separate roofs and either poured separate foundations or had the floor sawed for each room. We had one site in Johnson Creek, WI that was built this way. Sadly, the HVAC contractor screwed up and the THX rooms would not pass the NC Test. So he had to jack up all the roof units and install isolators under each unit. I did not shed a tear for that guy because we told him and the architect told him they had to be isolated. Once the isolators were in, it passed with flying colors and room to spare.

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          • #6
            Spoken like someone that...probably has never used resilient channel. Yeah, the channel is fastened to the drywall and the stud...just like a shock absorber is attached to the car chassis and the axel. The channel's job is to keep wall vibration from transferring into the studs and causing the studs to transmit the audio everywhere.

            You believe STC only goes to 65 because? When I've measured STC, I've followed ASTM's procedures and they never had an upper limit. THX (back in the day) called for STC 70-75 walls and the ones in the AFI/Silver (theatres 2 and 3) are definitely in that range. You NEVER hear sound transfer between the two theatres or even in the booth. And yes, it is true, that asymmetry is important to wall construction.
            Last edited by Steve Guttag; 07-15-2021, 10:36 AM.

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            • #7
              No, I never used resilient channel, but the Architect some times spec'd it, and the drywallers used it.

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