How Will I Know If My Room Needs Treatment?

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Doctor Varney

Cave dwelling Luddite
So, I'm finally in. Got the benches built and the gear arranged pro tem before taking it out to decorate and then putting everything back in place.

So to sound treatment. The question is, how will I know if it sounds good or bad? What am I listening for? How does an ideal mixing environment 'sound'?

As for purpose: I am narrating books and engineering audio plays. So it's mainly spoken word with sound effects and the odd ditty pressed out on the keyboard for incidental tunes and 'moodscapes'.

I'm not in a band. There will be no acoustic instruments (other than voices). Incidental music is all created and mixed digitally, inside the box, inputted through my Roland and Yamaha KB controllers. I intend to build a small floating booth to house one or two actors for when the time comes to expand my 'repertoire'. Any 'musical'-music I make will be for my own amusement.

This is the first time I've been able to take a room seriously and get a fresh start in a dedicated studio of my own. It is looking sweet!

I can insulate the booth easily as it's small. It will serve to cut out room/ computer/ road noise. I live on a quiet street with the occasional pedestrians and cars going past. The main part of the room has the mix position in the bay window, kB controllers to the left of me.

So the question is what am I listening for in the main part of the room, when it come to assess acoustic treatment?

Thanks for reading and I look forward to your replies.

Dr. V
 
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Our local national radio and tv station is using anechoic room for audio plays.
Since I don't think you want your room look like made of triangles :D (google for pics) I'd say that good room for audio books and plays has as little echo as possible and doesn't have bass buildups. If you can, you could rent measuring mic and get Room EQ Wizard. Measure your room and you will see the good and bad points of your room.
 
Well, as I said, I'm planning a booth... so perhaps I could make that a bit 'anechoic' with triangles and stuff...? I'm thinking mainly of the mixing/ control area for now, which occupies the larger part of the room.
 
For the first, assume that your room needs treatment. It does. It's that simple. Secondly, if you have the budget, hire an acoustician. In the long-run you'll see that it will be money well spent.
 
Real traps have/had a download file of pink noise across a range of freqs so you could play it back in your space & measure the SPL variation etc.
I used it - it was good value & pointed out some major things I needed to do to make the mixing spot sweet.
 
Its difficult to explain what type of treatments need your room, If you share some pictures of your room then its easy to share thoughts.
I think anechoic is best for you and i like this one because mostly use anechoic for radio plays.
 
I do not have the funds to invite acoustic scientists to my house. I just need to know what I am trying to eliminate. First, I recognize some short echoes when I raise my voice. There does not appear to be any 'bass build up' when playing music in the room. I do not recognise any problems when listening to recorded sound. Everything that is done will be DIY. I have some insulation left over from the loft, it is called 'Rockwool'. I have wood, I have lots of old carpet and I have tools. There are no funds for buying fancy materials.

What can I do with this? How to make best use of what I have?

I have arranged the mixing desk at the end of the longest part of the room, as suggested in most articles. I have a high-backed leather chair which came out of a recording studio, which probably absorbs sound behind my head.
 
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rayc said:
Real traps have/had a download file of pink noise across a range of freqs so you could play it back in your space & measure the SPL variation etc.
I used it - it was good value & pointed out some major things I needed to do to make the mixing spot sweet.
Click to expand...

That's cool. How does one measure SPL variations? With what? Then, how do I translate such measurements into room treatment?
 
Thanks for the responses! They are extremely helpful to me, as I now have a clearer idea of what I am looking/ listening for.

Rigid fibre glass I have not seen but 'fluffy' fibre glass I have plenty of and can purchase more at low prices. I can make the panels as shown here by making box frames covered with fabric. The question is, can I use the fluffy stuff inside these?
 
Doctor Varney said:
Thanks for the responses! They are extremely helpful to me, as I now have a clearer idea of what I am looking/ listening for.

Rigid fibre glass I have not seen but 'fluffy' fibre glass I have plenty of and can purchase more at low prices. I can make the panels as shown here by making box frames covered with fabric. The question is, can I use the fluffy stuff inside these?
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I did a big chunk of my treatments DIY' that allowed me the option to build some 6x4 foot panels that can double function as partions for example- 'Fluffy stuffed (and slightly compacted in this case
My take on it is exceot in the case for most efficient low-specfic traps, and mounting' ease (or not) the overall effect of the two densities are very similar.
 
mixsit said:
I did a big chunk of my treatments DIY' that allowed me the option to build some 6x4 foot panels that can double function as partions for example- 'Fluffy stuffed (and slightly compacted in this case
My take on it is exceot in the case for most efficient low-specfic traps, and mounting' ease (or not) the overall effect of the two densities are very similar.
Click to expand...

That's fantastic, mate. Thanks for sharing your experience. So, once I have the frames built, can I place some thin hardboard (compressed wood pulp board) across the back, to stop the fluff falling out? Or would you recommend string or nylon fishing line weaved across the back?

And when it comes to facing them, can I get away with using cotton fabric instead of expensive acoustically transparent material, like what is found over speaker grilles?

One more question - seems simple... but when we talk about these DIY panel frames, are talking about a bass trap or a sound-absorbtion panel? Is a bass trap different? I saw someone use a pile of wood block offcuts fixed into a semi-random pattern on his wall. It not only looked amazing but claimed to work as bass absorption.

Bloody hell! This is going to save on the heating bills over Christmas! :D
 
Since no one’s jumped in yet, I’ll give it another shot.. (Be advised this is homegrown’ seat of the pants stuff..
Doctor Varney said:
That's fantastic, mate. Thanks for sharing your experience. So, once I have the frames built, can I place some thin hardboard (compressed wood pulp board) across the back, to stop the fluff falling out? Or would you recommend string or nylon fishing line weaved across the back?
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First that would depend- if you want/need the benefit of both side’s absorption- A frame with some sort of wire/string to hold the stuff in, you can then pick up a bit more performance with a gap to the wall for example. A frame with a solid back side- doubt it would help offsetting off the wall(?), but- makes a better partition’ blocking sound. Two of my three large ones for example I did ‘solid one side, but that is I’m sure a practical traded-off- They absorb a lot, moveable, lean’ or stand where ever, but reflective on the back. Another one is solid down the center (deeper) and soft both sides- (The idea there was different- it lives as ‘bass amp-to-kit partition..

And when it comes to facing them, can I get away with using cotton fabric instead of expensive acoustically transparent material, like what is found over speaker grilles?
Click to expand...
Pretty sure anything that isn’t too tightly woven.

One more question - seems simple... but when we talk about these DIY panel frames, are talking about a bass trap or a sound-absorbtion panel? Is a bass trap different?
Click to expand...
‘Bass trap = deeper (for the most part). I expect you could just as easily call 2 or 3” of soft stuff a Mid/High trap-
I saw someone use a pile of wood block offcuts fixed into a semi-random pattern on his wall. It not only looked amazing but claimed to work as bass absorption.
Click to expand...
Sounds like diffusion. But you could probably have trapping built into it-? But I’m out on this one.
Bloody hell! This is going to save on the heating bills over Christmas! :D
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..make a little cubby', light up a few tubes amps :)
 
Well, that's just brilliant. Thanks, Mixit. I'm inpired to get going with this! You see, being on a tight home budget, the last thing I need is a guilt trip! :thumbs up:
 
Doctor Varney said:
So, once I have the frames built, can I place some thin hardboard (compressed wood pulp board) across the back, to stop the fluff falling out? Or would you recommend string or nylon fishing line weaved across the back?
Click to expand...

You might want to be careful using something as thin as hardboard as it can resonate, which would go against what you're building. I would go for stringing or netting.

Doctor Varney said:
And when it comes to facing them, can I get away with using cotton fabric instead of expensive acoustically transparent material, like what is found over speaker grilles?
Click to expand...

You can go with cotton material like broadcloth, or stuff like poplin or microsuede, whichever works best for you. However, it is hard to say which fabrics will and won't affect the absorptive qualities. Some may be too tight to let certain frequencies through, so it could be semi reflective. You can use speaker cloth as well, it isn't too expensive. I would suggest something like Guilford of Maine's FR-701 fabric though. They look amazing, they're fire treated, they're really wide, and they are almost 100% acoustically transparent. It is expensive, but very worth it IMO. The fire treated part is especially important too - most fabrics will light up in an instant if the unthinkable happens. Even if you go with a different material, I would suggest using flame retardant spray on the fabric to be on the safe side.

Doctor Varney said:
One more question - seems simple... but when we talk about these DIY panel frames, are talking about a bass trap or a sound-absorbtion panel? Is a bass trap different?
Click to expand...

There are quite a few different ways to build traps, and some work better than others at certain frequencies. For the most part, its broken down into two categories: velocity based absorbers, or pressure based absorbers. Velocity absorbers are the typical traps built with porous materials, like fiberglass and mineral wool. There are a number of different pressure based traps, like membrane absorbers, Helmholtz resonators, and tuned panel traps. Pressure based traps have to be a completely sealed enclosure, and are typically much harder to build. They work good for low frequencies at a small depth, so they are certainly another great tool.

A bass trap is any type of absorber, be it foam, rockwool, or resonator that traps bass frequencies. So, it can be the same as just a thicker sound absorption panel, but they can also be pressure based traps like stated above.

Doctor Varney said:
I saw someone use a pile of wood block offcuts fixed into a semi-random pattern on his wall. It not only looked amazing but claimed to work as bass absorption.
Click to expand...

What you were looking at was a diffuser. They are certainly not bass traps, and they usually don't effect frequencies under mid frequencies (around 800 Hz or so, depending on the size). There are many different types of diffusers as well. PRD, QRD, skyline, polycylindrical, etc. They look very cool and can be useful in studios and home theaters, but they are difficult to place correctly. I wouldn't recommend diffusion until after the low end is taken care of in rooms by absorption. You can check out our article we did explaining diffusion on our site here: http://www.gikacoustics.com/education_diffusion.html
 
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Thank you, GIK, for taking the time to type your informative reply.

I could get to work right now, without any kind of treatment and the results would no doubt be acceptable for the market I'm pitching into. At present I'm competing with people working in their kitchens and dining rooms with USB mics and laptops running Audacity. Slowly, but surely, we see the acoustical recommendations for upping the game coming in dribs and drabs on the volunteer sites. I aim to be ahead in the game with my DIY treatment and approach to recording, before more people get really good at this. I'm already several steps in front with my accent, timing, effects and theatrical training. The dream is to eventually find a room large enough to house a whole cast of actors with individual microphones.

The advice I have found here, combined with the provided links, is proving invaluable to the low budget I'm currently working to. So that's a +plus with regards to business start up costs; keeping them low to begin with. It's all too tempting to spend hours working on perfecting the environment before doing any work. I'm fussy like that but lessons have been learned.

A lot of sources suggest a floating booth/ whisper room to be superfluous and to concentrate on making the room good. I can see two advantages. One is psychological and actors arriving for solo performances will instantly feel you mean business and they are 'special' as soon as you usher them into a purpose made cabinet. The second is purely practical - it will be easier and cheaper to create an anechoic booth than to do that to the entire room, where there are many hard reflective surfaces posed by gear, shelving and so on... (It's also going to be great for storing bikes when not in use!). :)

So the treatment comes in two phases here... the first is the listening/ mixing area of the main room (what we've been talking about). The other is inside the whisper room. When I have the basic structure complete, I'll have a few questions about the insides.

Again - many thanks for the brilliant replies. If anyone has anything to add - I welcome it heartily!!!

Regards

Dr. V
 
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Cheers Dr. V,

Sounds like a good plan all in all. How large do you plan on making the whisper room? I would agree that it certainly sets the mood at bit more, and it can be nice to not have to be as careful about moving around while recording someone in the room - BUT! it can be dreadfully bad for the low end in someones voice with a tiny room. If you do go ahead and do it, I would advise a few suggestions:

Do not have any lengths that are multiples of each other. A 4x6x8' room would be just awful to record in. Also, if you can - angled walls will help tremendously, and will cut down on the amount of treatment necessary. In the case of a recording room, asymmetrical walls are preferred. And if you can, I would opt for fiberglass or mineral wool covered in fabric for the walls instead of foam, to help with the entire range of speech frequencies, instead of only attenuating the higher frequencies.

On the other hand, if you do end up recording in a room, move-able gobos can be very useful. Something like this: Screen Panel : GOBO : GIK Acoustics
 
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