How To Make An Acoustic Ceiling General Woodworking
Moving forward with the improvements to my office, the room acoustics are the next on the list. Along with the video editing, I’d also like to do any of the voice over recording that’s needed in here, rather than out in the shop. However, the largely empty room with flat parallel surfaces needs to be treated in some way to make it suitable for recording
One way is to build individual absorbers and diffusers, much like my skyline diffuser, but these take up space in the already too small room. As part of my overall idea for the interior design of the house, I thought a wood slat ceiling would not only look good, but also deal with the problems with the sound. This type of acoustic treatment is often seen in recording studios and will have slats and gaps of varying width that are specifically designed to work with the specific room. As usual, I’m being just a bit less “scientific” with mine, knowing that my requirements are not as strict.
Here’s the basic idea:
This is a section view from the end of the room. With bulkheads on either side that have a large opening for the LED light to come through, these also have some fiberglass insulation stuffed into the ends to absorb the sound that enters through the hole.
The slats are bowed down in the middle slightly, and this helps to prevent standing waves between the floor and the ceiling. The space above the slats act as a Helmholtz resonator, absorbing frequencies in the mid-low to midrange. The distance between the slats and the original ceiling largely determines the frequencies it will effectively absorb, but I couldn’t go too deep here. And since the room is used for the spoken voice, there’s typically not enough low end deal with. The hard surface of the slats also reflects higher frequencies making the room sound more “live”.
First step was to make and install the bulkheads on both sides:
These are made from 1/2″ plywood and have a single 48″ LED strip inside pointing at the wall. The large opening lets the light out, but also lets sound in, and with fiberglass in both ends, acts as a Helmholtz resonator as well.
Next, furring strips were fastened to the ceiling:
The slats will be attached to these and they are sized to bow the slats downward in the middle.
Thin layers of fiberglass were stapled in the spaces between the furring strips and then the whole thing was covered with a black cloth:
The cheapest way to get material this size was to order a big tablecloth online for $10.
I installed the slats starting from the middle, and working toward one end. I used a 23 gauge pin nailer to fasten the slats, removing the staples and pulling the cloth taut as I went:
The pins are tiny and difficult to see, so don’t require any filler.
I did half of the slats at a time, since there was a lot of work involved in getting those sanded and clear coated.
To finish it off, I made a 1/2″ square trim strip that I painted white to cover any gap at the ends of the slats. The cloth was also pretty ragged looking after trimming off the excess, and the trim helped to cover that.
And how well does it work? Splendidly. The treatment completely eliminated the reverb that was present before, making the room much more suitable for recording. In fact, the voice over in this video was recorded in the in the room: