How to Build Your Own Acoustic Panels (DIY)
Last Updated on Wednesday, 4 June 2014 09:10 Written by AcousticsFREQ Thursday, 13 October 2011 08:41
Make Cheap, Easy, Attractive DIY Sound Absorption Wall Panels
Also Check out our Complete Guide to Home Theater Acoustics for more information, including where to place your acoustic panels.
Equipment List (per panel)
- (one) 2’x4’ fiberglass or rockwool absorption panel (~$6.60 per panel)
- (two) 1” x 2” x 8’ wood furring strips (~$1.44 per panel)
- wood glue
- (four) wood screws (#6 x 1-1/4″ flat head phillips)
- (two) 20-lb rated picture frame hangers
- (two) Heavy duty D-ring hangers w/ screws
- 62” length of fabric, minimum 36” width (~$10 per panel)
- spray adhesive
Total Cost is about $20 per panel, or $2.50 per square foot.
*Note that choral music, piano, orchestral instruments, group singing, and pipe organ benefit from reasonably reverberant acoustics, with many reflective surfaces. Installation of sound absorption material can harm musician performance and sound quality for these specific applications.
Suitable applications for sound absorption panels include:
- Improving surround-sound imaging and clarity for dvd/blu ray movies, sports, or video games in a home theater
- Reducing slap-back echo and reverberation in large halls, auditoriums, and contemporary churches
- Reducing chatter, din, and noise in crowded gathering spaces, restaurants, or bars
- Providing more accurate listening conditions in recording studios and control rooms
Note that sound absorption material is often called “soundproofing.” I believe that the term “soundproof” is usually misapplied, which will be discussed in another post. Sound absorption panels are NOT able to significantly reduce sound transmission through a wall between two adjacent spaces; they are intended to improve sound quality and reduce noise levels within the room that they are installed. Commercially-manufactured sound absorption panels are available in two common varieties:
2) Decorative fabric-wrapped fiberglass panels (e.g. Wall Technology, Fabricmate, etc.):
The acoustic properties of each of these are very similar, with all of them absorbing approximately 100% of incident sound energy at mid and upper frequency ranges. Feel free to compare Sabine absorption coefficients at your leisure. These material types are mostly differentiated by their visual appearance.
An important consideration for any sound absorption panel, though, is thickness. A thicker panel will more effectively absorb a longer wavelength (lower frequency) of sound. Therefore, when choosing an acoustical material, consider the frequency content (tonal spectrum) of sound that you seek to absorb. For placement on drywall surfaces, the following rules of thumb should be helpful:
- For human voices, crowds of people, and speech use 1” absorber thickness
- For amplified music with bass and drums or cinema surround-sound use 2” absorber thickness (or greater)
The necessary quantity and placement of sound absorption material for a given space is determined by the specific type of listening functions occurring there. Extreme ends of the spectrum range from traditional/classical worship spaces which are entirely hard-surfaced (great for pipe organ and choral music) to THX-certified cinemas and movie theaters which have sound-absorbing materials on all wall, floor, and ceiling surfaces.
Consider which wall and ceiling reflections need to be eliminated and cover those entire areas with sound absorption treatment.
Pricing for manufactured, two-inch thick, fabric-wrapped fiberglass sound absorption panels is usually $6 to $8 per square foot. I have seen sound absorption panels priced as high as $12.25 per square foot! Given the large square foot area that needs to be covered to achieve a suitable home theater acoustic, this falls well outside of the average consumer’s budget.
I may annoy a few people by telling you this, but you can make your own sound absorption panels for MUCH less. What follows are explanations, instructions, and specifications for very effective sound absorption panels.
The essential elements of a sound absorption panel include:
Step 1: Select a sound-absorbing core material
The sound absorbing core material must have the following characteristics:
- Dense fiberglass board insulation (not loose batt)
- 3lb to 8lb density
- 2” thickness
Three acceptable material options include:
Johns Manville 817 Spin-Glas 6lb pcf, 2″ thick: ~ $3.73 per square foot.
Owens Corning Fiberglas 705 6lb pcf, 2″ thick: ~ $3.06 per square foot.
Roxul Rockboard 80, 8lb pcf, 2″ thick: ~ $0.78 per square foot.
These can be purchased from your local insulation supply dealer.
My prototype panels were built with the Roxul RHT 80 insulation, which is the least expensive sound absorption material that I have found. The Roxul acoustical performance is similar to the Owens Corning and Johns Manville products, but it is softer and has a less regular shape. The manufacturer-supplied sound absorption coefficients are as follows:
2″ Roxul RHT 80 2” Owens Corning 705 2” Johns Manville 817
125 Hz = 0.39 125 Hz = 0.16 125 Hz = 0.38
250 Hz = 0.84 250 Hz = 0.71 250 Hz = 0.93
500 Hz = 1.08 500 Hz = 1.02 500 Hz = 1.10
1000 Hz = 1.01 1000 Hz = 1.01 1000 Hz = 1.07
2000 Hz = 1.02 2000 Hz = 0.99 2000 Hz = 1.07
4000 Hz = 1.01 4000 Hz = 0.99 4000 Hz = 1.07
Sabine absorption coefficients are roughly the ratio of reflected sound absorbed. So, at a given frequency range, a 1.00 coefficient equals a 100% absorption rate (0.71 equals 71%, etc). Note that these figures are provided by the individual manufacturers and tested in different labs. It is safe to assume that each of these materials is equivalent to the others.
Step 2: Build a wood frame around each panel
- For each panel frame, cut two segments of furring strip to 49-3/8” and two segments to 24” (check measurements with your sound insulation panel and furring dimensions).
- Arrange wood segments around the fiberglass panel.
- Position the insulation such that the bottom face of the panel is flat and level with the wood frame.
- For each corner:
- Pre-drill a pilot hole for one corner to ensure alignment and prevent the wood from splitting.
- Apply wood glue.
- Screw wood segments together.
- Remove panel core from frame, apply spray adhesive to entire perimeter, them firmly re-seat. (glue will hold the insulation in position within the frame).
- Allow 24 hours for wood glue and spray adhesive to dry.
Step 3: Select a sound-transparent fabric; wrap the panel
The most common fabric choice for commercial panel manufacturers is Guilford of Maine Panel Textiles. This is a high-quality material. That being said, there are a great variety of inexpensive fabrics that can work equally well. Colored burlap is a very common choice. My prototype panels use a Keepsake Calico paisley material purchased from a local fabric store. Considerations for your fabric cover:
- Must be “breathable” and sound-transparent
- Ensure that your fiberglass panel is not visible through the fabric
- Beware that fabric with visual patterns will be tricky to line up squarely when stretched over the wood frame
To stretch the fabric to your panel:
- Lay a 62” length of fabric (face down) on the floor.
- Place your framed panel on top of the fabric with the flat/level/even side facing up.
- Have a friend wrap the fabric around the backside of the panel and staple it to the wood frame every 3” along one of the edges.
- Stretch the fabric tightly along the opposite edge and staple, continuing along the panel edge at 3” intervals.
- Repeat steps 3 and 4 for the top and bottom edges, taking care to neatly fold each corner.
- Apply spray adhesive underneath the remaining loose fabric areas on the back side of the panel.
Step 4: Mount the panel to your wall or ceiling
Detailed steps for finding the best placement locations for sound absorption panels in a home theater can be found in our detailed article: Where to Place Sound Absorption Panels in a Home Theater.
These panels can be mounted similarly to a heavy piece of artwork. Use your discretion and judgement to make sure that your panel is safe, secure, and stable. I screwed two heavy-duty D-Ring hangers on each side of the wood frame, measured to exact spacing. These were hung on two 20-lb rated picture hangers. See the Equipment List below for hardware recommendations.
Step 5: Listen
Now you are ready to enjoy your music or home theater the way that it was intended. Most people are surprised to hear what music and movies sound like in a properly-treated acoustic environment. The audible difference cannot be overstated; it is like night and day.
June 4, 2014 update:
Here are some photos from a recent build by our reader Mike:
Join the discussion on our new AcousticsFREQ.com online forum! Check it out at www.acousticsfreq.com