Archive for category Theater
We often get asked about the functionality of the different diffusers, and one of the frequently asked questions is about the differences between the ArtDiffusor® Model C and ArtDiffusor® Model F. We will cover some of similarities and differences in the design, functionality and use of these two devices.
The Model C and Model F use identical math to come up with their basic structure, they even have angled faces – the main difference between the two is that the Model F elements are ½ of the Model C’s height, length and width – and then it is duplicated 4 times in the same footprint… The Model C is nominally 2’ x 2’ x 4” deep. The Model F is four quadrants that are nominally 1’ x 1’ x 2” deep – like little scaled down Model C’s… This makes them visually similar and aesthetically compatible. This low profile design makes the Model F more desirable for ceiling installs in spaces with very limited headroom – like basement studios that have low ceilings.
Due to the different size of the elements on the two devices, they have very different frequencies at which they are most effective. The Model C is a mid-frequency diffuser by design… having larger elements and deeper wells than the Model F. The Model F is primarily a high-frequency diffuser, due to the small elements and lower profile. Both diffusers are tuned to different frequencies as their “primary range,” and while they do affect lower and higher frequencies than they are designed for – it is to a lesser degree, or the product of absorption.
What does this mean?
The Model C has a primary design range of 1KHz to 4KHz. This is where it is primarily designed to work. It can and does diffuse below 1KHz and over 4KHz – just to a lesser degree than its primary design range.
The Model F has a primary design range of 2KHz to 8KHz, and again, it does diffuse outside of that range, but to a lesser degree.
The angled caps of both the Model C and Model F help to extend their high frequency range by reflecting sound in different directions at higher frequencies – causing the sound to scatter spatially. The different heights of the elements cause sound reflections to be offset “temporally,” or in time. The sound that hits the higher elements is reflected sooner than the sound that hits the lower elements – travelling further before it is reflected. This time offset, changes the “Phase Coherency” of the reflection; the larger the difference in the heights, the greater the offset in time.
The size of the elements matters as well. The shorter wavelengths of high frequencies can diffract and scatter off of the smaller elements of the Model F more readily than low frequencies, which see the Model F as a slightly angled & mostly flat surface. However, the lower frequencies are more affected by the larger and deeper elements of the Model C.
How do these differences help define their use?
The Model C is a great all around diffuser – it covers a wide range of frequencies, throws a very predictable 2D diffusion pattern, and it is tuned to a very musical range.
The Model F is a great high-frequency diffuser. It targets a few very specific, yet important issues. High frequencies are responsible for some nasty problems in rooms. Flutter echoes, ringing, comb filtering, and other artifacts are particularly noticeable in higher frequencies. If your room is otherwise performing well acoustically, the Model F can help tackle that last hurdle to make a good room into a great room.
For anyone new to the world of acoustics, there is a multitude of terms, coefficients and numbers that are thrown around. This flood of information can seem intimidating, especially to beginners. In this series, acoustician Cameron Girard of Acoustics First® hopes to help you distinguish between what’s useful and what’s not.
Part 2: How Mounting in Testing Affects Sound Absorption Data
As I discussed in my previous article, the best way to compare the performance of sound absorbing panels is by referencing the Sound Absorption Coefficient (SAC) and Noise Reduction Coefficient (NRC). However, these coefficients are often used as marketing tools. Be on the lookout for companies that list absorption coefficients and NRCs without mention of a particular testing standard or mounting method. It’s vital to check for this information, as direct comparisons to competitors and other materials can only be made if their testing procedures are the same.
The sound absorption of a material that covers a flat surface not only depends on the physical qualities of the material but also on how the material is mounted during installation. The mountings specified in laboratory tests are intended to simulate conditions that exist in normal use, such as direct wall mounting and installation into a ceiling grid.
Many materials for treatment of walls or ceiling are tested using what is called Type ”A” mounting. Type ”A” mounting means the test specimen was placed directly on the test surface of the reverberation chamber. Lay-in ceiling tiles, on the other hand, are often tested using ”E400” mounting. The ”E” designates a sealed air space behind the specimen (simulating the air gap between a dropped tile ceiling and the structural ceiling) and the number after the ”E” is the depth of the airspace in millimeters. The airspace behind the acoustic material affects the sound absorption by acting as a bass trap. The deeper the cavity behind the panels is, the lower the fundamental of the “trapped” frequencies will be.
To see what this look like in terms of actual numbers, let’s take a look at how different mounting methods effect the sound absorption coefficients of Acoustics First’s HiPer® Panel (a low-profile, composite absorber/diffuser panel).
Since the HiPer® Panel can be used effectively in multiple applications; we had it tested in accordance to the two most-common mounting procedures, Type E-400 and Type A. The results of the laboratory tests are as follows:
Sound Absorption Coefficients
|1″ HiPer® Panel||1″||E-400||0.43||0.28||0.51||0.76||0.99||1.10||0.65|
|1″ HiPer® Panel||1″||A||0.09||0.28||0.78||0.75||0.94||0.85||0.70|
As you can see from the chart, the sound absorption coefficient at 125 Hz varies greatly between E-400 mounting (SAC of .43) and Type-A mounting (SAC of .09). If mounting the HiPer® Panel in a ceiling grid, with a sizable airspace, you can expect significant low-frequency absorption, but mounting it on a wall (Type-A) will result in much less absorption at 125Hz.
Other mounting methods are available, but are not used as frequently. Here are some of the basic mounting designations (See ASTM E795 for more information.)
Type A mounting – Test specimen laid directly against the test surface (wall panel on drywall).
Type B mounting – Test specimen cemented directly against the test surface. Type B mounting is intended to simulate acoustical ceiling tiles or other sound-absorptive products adhered to a hard surface with an adhesive.
Type C Mounting—Test specimen comprising sound-absorptive material behind a perforated, expanded, open facing or other porous material.
Type D Mounting—Test specimen mounted on wood furring strips.
Type E Mounting—Test specimen mounted with an air space behind it (dropped tile ceiling).
As we’ve discussed, acoustical data can vary greatly depending on the mounting method used during testing. Acoustics First tries to include as much information about testing procedures as possible, because we feel an informed client makes the best client.
Contact Acoustics First for your all your sound control needs!
Posted by Acoustics First in Absorption, Articles, Broadcast Facilities, Customer Feedback, Diffusion, DIY, Home Entertainment, Home Theater, HOW TO, Media Room, Music Rehearsal Spaces, Music Tracking Room, Product Applications, Recording Facilities, Recording Studio, Studio Control Room, Teleconferencing, Theater, Vocal Booth, Voice Over on July 14, 2016
This month we thought we’d share a few Real-Life pictures of an idea we first introduced back in summer of 2013: The “Back Wall Diffuser Array/Bass Trap”.
This is the DIY project which incorporates our Art Diffusors®, Cutting Wedge® foam and a couple of isolation hangers into one large free-floating unit, which is acoustically decoupled from the wall.
This particular array was put together by a music producer/bass player for his home. As you can tell from the pics, the construction of this unit was executed beautifully and it’s very close to the original concept drawings.
It’s never too late to get started on your own DIY project.
Posted by Acoustics First in Absorption, Animal Shelters, Auditorium, Broadcast Facilities, Classrooms, DIY, Fitness, Government, Gymnasium, Home Entertainment, Home Theater, HOW TO, Media Room, Multipurpose Rooms, Music Rehearsal Spaces, Music Tracking Room, Product Applications, Recording Facilities, Recording Studio, School & Educational Facilities, Sound proofing, Studio Control Room, Teaching Rooms, Teleconferencing, Theater, Uncategorized, Vocal Booth, Voice Over on July 16, 2015
On many occasions, we get asked about common ways to treat a wall (or walls) either for broadcast, podcast, or other voice recording scenario – where they not only want to tame the reflections within the room, but also block a certain amount of sound coming into – or leaving the room.
Budget is frequently an issue, major construction is usually unwanted, but effective results are always required.
We’re going to show you how to handle a room upgrade – cut down on the sound transmission and cut the room reflections – all with the same skills required to hang high quality wall coverings! Let’s see how you can cover a wall with BlockAid® vinyl sound barrier to block unwanted sound, then go back and cover that with an absorptive layer of Sound Channels® wall covering to finish it off!
This treatment is not recommended for renters, as this is not an easy upgrade to undo. However, if you have an extra bedroom you are using as Podcast studio, this is a great way to treat it… Let’s get started!
Good job! Now, take a breather while that dries, and notice how much less sound is passing through the walls. This is when you will notice that the sounds are now coming from under the door, and through the leaky old window. These can be taken care of in different ways…. but the easiest way is the same way you deal with keeping the cold out! Get some weather strip, a door skirt, seal the gaps around the frame of the door, and windows, maybe go out and buy some heavy curtains for the windows… if you have some leftover BlockAid®, you can always get some Industrial Velcro and temporarily stick a piece over the window!
Installing Sound Channels®
This treatment is a common first step in treating many professional broadcast studios – it gives you extra isolation with the barrier and takes the edge of the sound reflections. Many professional environments then go back and add some additional treatments such as bass traps, diffusers, and broadband absorber panels – especially if these studios are planning on bringing in any musical guests.
This isn’t just for home studios. It works great for kids play rooms, bedrooms, home theaters, home gyms, and any place you want to block sound and tame the sound inside the room.
Customize your space as you will, but this treatment is a consistent winner for cost and performance, and is a great way to get started without breaking the bank!
Yocumtown Church of God had a bit of an issue with their multipurpose room – They couldn’t understand anything anyone was saying.
While the space was designed well with a full court, dampers on the HVAC, a stage, movie screen and a good speaker system – they couldn’t overcome the poor acoustics of the space. A great deal of work had gone into the design and they wanted an unobtrusive way to treat the acoustic problems… enter Acoustics First.
We started the work of gathering information about the space; dimensions, some pictures and a few balloon pops.
Here’s what we got.
Wow! This room is big, all the surfaces are parallel and hard, there’s very little to break up the sound… You can almost imagine what it sounds like.
You actually don’t need to imagine. Here’s a balloon pop. CLICK HERE!
What you’re hearing is about 3.5 seconds of reverberation after the balloon pop. (Not good.)
So, whatever shall we do? How will we tame this space?!?!?! Will they ever be able to have movies for youth groups!?
Sure they will! We have Joe. You remember Joe from the Sabot School Big Room Big Boom Post?
Well, I would say that Joe has a 6th sense for hearing, but since that’s one of the 5 standard ones anyway, we’ll just say Joe has great ears – and they should be. Joe’s been using his ears as his primary tools for the past 40+ years; from Studio Engineer to Acoustic Engineer. His ears are tuned instruments, and we rely on his expertise with them to get the job done right – time and time again. (He also makes a mean spreadsheet.)
So after listening to the room, looking at the data, and running some numbers – Joe magically answers the question of what do they need? (Ok it isn’t magic – Joe’s just really good at this… did I mention his spreadsheet skills?)
So Joe says, “You put 280 – 4’x1′ Cloudscape®baffles up on that ceiling and you’ll bring that room down from about 3.5 seconds to about 1.5 seconds.”
Not only does it look great…
… But now they say that they can watch movies and it sounds just like you’re in a movie theater.
That’s about the best compliment you can give us.
(And the best compliment I can give Joe is, his calculation for RT60 time was about 1.5 seconds. When I ran the measurement of the “treated balloon pop” – I got 1.501 seconds. This is why we have Joe – he can tell you what you will get, before you even start!)