Posts Tagged ‘sound absorption’

Questions about your recording environment? Bryan Pape has answers!

February 12, 2010

I’m thrilled to introduce Bryan Pape, who has agreed to appear in a series of blog posts to help us better understand room acoustics, sound treatment and related topics that directly affect the quality of any audio you record or listen to.

Bryan is the lead acoustical designer for GIK Acoustics, a respected sound treatment manufacturer and dealer, as well as owner of Sensible Sound Solutions, through which Bryan sells sound treatment services and materials.  Bryan also lends his advice to thousands of audio enthusiasts and recording engineers in several online forums, including the popular Gearslutz’ studio construction and acoustics forum.

I’ve asked him a few questions to get started. Here we go:

Q: People who listen to, mix or record music spend thousands of dollars on equipment — stereos, speakers, microphones, preamplifiers, etc., all carefully selected. Yet most don’t spend much time considering the space in which they listen to or record music. Why, in layman’s terms, is the space as important as the equipment?

A: Yes. That’s a real problem. The the things that influence what you hear more than anything else are:

- The room

- The speakers

- How you and your speakers are positioned within the room.

Your room provides gain to your speakers, impacts what frequencies build up and which ones get canceled, etc. The way the room is constructed determines how it absorbs and reflects sounds of different frequencies. For instance, two identical rooms, one with a wood floor and one with a granite floor, will sound different, even though both are ‘hard’ surfaces. They just have different resonances, flex differently, absorb differently, etc. Everything in the room works this way – walls, floors, windows, furniture, people, etc.

Q: What is the difference between sound proofing and sound treatment?

A: Sound proofing is trying to stop sound from entering or leaving a room. Treating the inside of the room for best acoustics will do nothing in terms of stopping sound getting in or out. They’re just two completely different things with very different solutions.

Q: Picture a person listening to music in a typical living room or bedroom environment: the walls are parallel, the speakers are up against a wall. What are some of the problems with this approach?

A: The biggest problem is that it’s reality. People have square and rectangular rooms. Parallel surfaces allow standing waves to build in in a space. Non-parallel walls can help minimize that depending on how much they’re out of parallel in relation to the wavelengths of the frequencies in question.

Most people don’t really have the space to splay the walls enough to really minimize bass issues. Most of the time, you’re better off having the larger space and dealing with the standing waves (modes) via treatment and careful placement to avoid sitting in the problem areas.

Q: Given those realities, what are three or four basic things people can do to improve their listening or recording environment?

A:  – Experiment with your seating position to get into a good position to avoid big bass mode problems.

- Try to maintain good left to right symmetry in front of you

- Experiment with speaker positioning. You can drastically change the sound of a speaker by where it is in relation to the room boundaries and where it is in relation to you. Sometimes you can deliberately introduce a ‘problem’ in a certain frequency range which will counteract another ‘problem” based on where you’re sitting.

- Learn your room and what changes to positioning do. Download Room EQ Wizard and take some measurements and see what it’s doing, what changes in seating position do, what changes in speaker positions do.

- Don’t get completely hung up only on frequency response. Decay time is just as important.

- Be realistic with your situation. Don’t try to use speakers that are too big for the space you have to work with. In a small room, you’re going to want to sit nearfield (i.e., use smaller speakers and sit closer to them).

- Don’t put your speakers in a corner – ever.

- Don’t sit right against a wall. This is the worst place for accurate bass response. (Editor’s note: Check out GIK Acoustics very helpful guide to setting up a room here, and Ethan Winer’s setting up a room guide here.)

Thanks Bryan! In future weeks, Bryan will address sound absorption in more detail as well as room modes, room treatment options, the dead/live room quandary and much more. If you have a specific question about sound treatment and related subjects, post it here and I’ll ask Bryan to address it in a future blog post.

Studio construction update!

August 3, 2009

It’s been a while since I last posted about my studio build, so it’s past time for an update.

As you may or may not recall, I’m building a small recording studio in the basement of my St. Louis area house. As we live on a quiet street and I won’t have to record much when my children are up, “sound-proofing” – or isolation – isn’t a primary concern. But I really want a good-sounding room, which is a challenge given that it’s a smallish space at about 12 feet by 10.5 feet, with ceilings not quite eight feet tall.

Because the space was in a completely unfinished part of our basement, I hired someone to frame walls and run electrical wiring. (I know my limitations!). Here’s a look at the studio space after framing and wiring.

studio 004studio 005

I said that sound isolation wasn’t my primary concern. However, I’d like to dampen as much sound as I can, within reason. Insulating the space within the walls is an excellent way to cut down on sound transmission. So I put the pink stuff between the joists on the ceiling above and between the studs of the walls.

insulationThen it was time for drywalling, something I’ve never attempted. I chose standard 1/2-inch drywall. Note that I had to drywall around a support beam, too.

A couple things I learned during my many hours of measuring, cutting and hanging drywall:

1. Measure twice, then measure again. Especially if you haven’t done this sort of thing before.

2. The strength of this stuff isn’t the gypsum, it’s really the paper on the outside. So if you drive your screw all the way through the paper, you need another screw.

3. It’s really not smart to hang drywall on a ceiling yourself. I tried, and pretty much failed. Luckily my strapping 14-year-old son, Jackson, was able to help. Thanks Jack!

Here’s a couple drywall pics:


You can see I’m no pro! But I’m going to hire some to do the mudding and taping, activites that actually require skill.

Now remember I mentioned how I want the room to sound good first and foremost? A key to preparing a room for recording and mixing is cutting down on the nasty echoes that soundwaves make. This results in muddy sound, with some notes being too loud and, oddly, some notes disappearing almost completely!

There are a raft of products claiming they will make your room sound like Abbey Road. (I mentioned some of them here). Some of them are quite good. But for the biggest bang for your buck, I think it’s best to make your own sound treatments. The key here, I’ve learned, is using either rigid fiberglass or rock wool, both of which absorb a wide range of sound.

I chose a combination of Owens-Corning rigid fiberglass — OC 703 and 705, to be precise – and some fairly dense rock wool. Note that the fluffy fiberglass — so good for insulating your home — really doesn’t do the job here, unless you can pack in three or four feet of the stuff in each corner of your room. So you need the “rigid” kind of fiberglass, which isn’t carried by your local Home Depot or Lowes. Here in the St. Louis area an excellent source for this do-it-yourself material is Bryan Pape of Sensible Sound Solutions. You can also mail order the stuff from several sources, including AST Acoustics, which I’ve used in the past.

So how do you get this stuff in your recording space? The easiest way is to simply wrap a couple panels in fabric. They generally come in four-foot-by-two-foot sections of two or four inches in thickness. But many people prefer to frame them in wood, which is the approach I’m taking for some of my treatment, as you can see:


I chose to use one-inch-thick-by-four-inches-wide pieces of wood –making a rectangle of four feet by six feet — to make four-inch-thick panels of OC 703 fiberglass. I will use them to dampen my “first reflections” from my monitors — a concept we will explore in a future post on treating your recording and listening room.

A warning: This stuff, much like the fluffy fiberglass, is rather nasty to handle. Rubber gloves, long-sleeved shirts and perhaps even a dust mask are good precautions.

Here’s the final panel, which I will cover with fabric before installation:

backup july 2009

Tips on building a small studio

May 14, 2009

IMG_0556As I’ve previously written, I’ve starting building a small tracking/mixing room for my studio, Getting Better Recording. Even when it’s finished, it will be quite humble by pro studio standards – it’s just a room I’m finishing out in my basement, after all. But I thought it would be fun to share a few things I’ve learned about creating a recording and mixing space from some very smart people.

I’ll expound on my plan and my choices soon. For now, here are my tips to creating the recording space of your dreams.

1. Know exactly what you want to do there. This is crucial. Will you be recording full rock bands or just one or two acoustic tracks at a time? Will you track live drums? Doing a lot of mixing or mastering?

The answers to these questions will guide much of your plan in terms of space.

2. Know the difference between soundproofing and sound treatment. This also is a hugely important point.  Lots of people start out assuming they want to “soundproof” their recording space. But true sound-proofing can be extremely difficult and expensive. Why? Simply put, sound is hard to contain. It takes mass – thick, heavy walls. True sound-proofing also can require decoupling floors and even the ceiling from surrounding structures, a tricky proposition at best.

Now there are a host of products and construction techniques that can help get you there: resilient channel, Green Glue, floating floors, room-within-a-room construction. If you have the time and money, these are all worthy areas of exploration.

Regardless of what you choose in this area, every recording and mixing room needs sound treatment. Which brings us to…..

3. Know the basic principles of treating a room for sound. When it comes to recording or even just listening, walls, floors and ceilings can be your enemy. Why? Because soundwaves tend to bounce off those hard surfaces, creating all kinds of problems for you. In short, the sound bouncing off all those surfaces competes with the sound coming out of your speakers — or your instrument.

So, you need to absorb some of that sound. Now lots of folks swear by the eggshell foam method – just get a bunch of that stuff and attach it to your walls and you’re set.


As has been pointed out in numerous places, thin foam — even that stuff sold by reputable companies like Auralex -- only absorbs high and middle frequencies. It leaves those big bass notes bouncing around, muddying up your sound and wreaking havoc with your recording.

One solution: homemade bass traps and sound absorbers. There are plenty of places to look to see how these things are built; when I build some more I will post the details on how I do it.

4. Set a budget. Then prepare to break it.

Sure, money can’t buy you love. But it takes money to create a good-sounding room. And if your experience is anything like mine, money will be a huge part of the equation. So set reasonable expectations and build a budget around it.

Ok, enough for now. I’ll be back soon with an explanation of some of the choices I’m making.

How to set up your recording space

April 6, 2009

People who record audio LOVE talking gear – the latest recording equipment, the fastest computer, the best microphones, etc. What most of us fail to realize is that the SPACE in which you record is at least as important as these other factors. Here is a fantastic tutorial on creating the best possible space in which to record, courtesy audiotuts+ website. It’s chock full of good information.

Also, note my past posts on the topic here, here and especially here.


Basic principles of acoustics

March 3, 2009

I’ve written recently about creating a good-sounding space for your podcasts and other recording endeavors. In that post I gave a big shout-out to a small company that makes sound absorption materials, Real Traps. Its founder Ethan Winer has been one of the web’s leading writers on sound absorption, sharing his ideas and thoughts with thousands free of charge. But today I wanted to give props to a competitor, GIK Acoustics, which has this concise, well written primer on acoustics that offers a good read to anyone interested in good-sounding recordings. Enjoy.

Recording tips: Sound treatment

February 27, 2009

So you’re ready to record some audio for a project — a voiceover, perhaps, or an interview. You have your microphone and your digital recorder or computer interface. What next?

You need to think about how your studio sounds.

Don’t have your own recording studio? Don’t worry – most folks don’t. But with a little work and not too much money, you can create a space in which you can record the human voice effectively.

Here are four tips to creating your own recording space:

1. Find a time and a place where you can have some quiet. Kids, neighbors’ lawnmowers, colleagues’ telephones – all can ruin a good recording. So find a room, or even part of a room, where you can get some quiet time. And arrange to be there whenever it’s most quiet. If you have noisy central air or heating, try turning it off during recording.

2. Try to avoid a tiny room. This may seem counter-intuitive, but a super-small space is going to have worse problems than a bigger room. The trouble is caused by sound waves bouncing off walls, ceilings, floors and each other, creating areas where certain frequencies are enhanced and others are reduced. In layman’s terms, a small space with hard, parallel walls will sound… bad.

3. Absorb some sound. Most people think they need to “sound-proof.” While real studios certainly do this – and they should – you don’t really need sound-proofing, you need sound absorption.

Allow me to explain: True sound-proofing is really about adding mass to  your walls, floors and ceilings. It ain’t cheap. The good news is for most voice-over and podcast-type work, you don’t really need sound-proofing, assuming you can get the kids out of the house or that you can find a spare room in the office away from the water-cooler chatter.

But sound absorption is absolutely necessary for most audio recording. That’s because most of the crap that can seep into your recordings comes not from the direct sound – from source to mic – but from the sound that reflects off the walls, bounces around your corners and THEN back into the mic. Without getting technical on you, that can create all manner of problems, as I said above.  So you need to find some material to absorb at least some of those reflections.

You’ve no doubt heard of foam products like Auralex. I am going to advise that you stay away from them. They cost a lot for the performance they provide.

Instead, make your own sound absorbers using rigid fiberglass. There are plenty of tips around for how to do this, so I won’t go into that now. But call around to insulation supply companies and find a source for Owens Corning 703. Note: This is NOT the pick stuff you lay down on  your attic floor. That stuff will work to a degree. If it’s all you have, throwing a roll of the pink stuff in the corners of your recording room will absorb some sound. But it won’t work particularly well. Rigid fiberglass is much more dense than the fluffy stuff, and therefore it absorbs much more sound. You’ll need to cover it in some kind of thin cloth, because it’ll make your skin scratchy if you handle it.

If you don’t have time for all that, you can find several reputable dealers of pre-made sound absorbers that use OC 703 and similar materials, like Acoustimat, GIK Acoustics and especially  Real Traps. That last company’s website is a treasure trove of acoustics information, provided free regardless of whether you purchase their products. Read up.

4. Get out of the corner. Corners amplify bass frequencies, but they don’t do it in a linear or predictable way. You may find a random note RESONATING while the very next note disappears. So whether you’re recording or listening, get away from the corner and even, if possible, from a wall. Many audio experts say the best listening position is about 1/3 of the way into the long portion of the room.

Happy recording!


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