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Help with Room Accoustics

01 Nov 13 - 05:05 PM (#3572063)
Subject: Help with Room Accoustics
From: Janie

Not a room for music, but a small office for my psychotherapy practice. I recently rented a cheap space in an old office building when I expanded my private practice to include one day a week in a town 30 miles away. I need some ideas for inexpensive fixes regarding the accoustics of the room, as well as some soundproofing.

I need to spend as little as possible to make it a workable space for it's purpose.

The office is 15 ft. square. 10 ft. ceiling. Marble floor. Plaster walls. One large 6.5 ft. x 5.5 ft. window. Wooden door to the corridor with open, non-closable wooden baffles at the bottom, probably for air circulation to the hall. The building was built in the late 50's, pre AC. (Has central AC now.) I need to deaden the accoustics, at least somewhat. Right now the echo and ring from our voices make it hard to hear, and makes it feel like a public rather than a private, safe space. I have several clients who are somewhat hard of of hearing, and I also have some hearing impairment. Voices get raised in an effort to compensate.

I can afford to buy a couple of area rugs for the floor but that won't be enough. I'm thinking that hanging fabric from the walls will help, but can't afford rugs or heavy tapestries or the heavy-duty hardware it would take to hang them. Anyone know how much effect hanging lighter-weight fabrics might have on dampening the sound in such an environment? I would like to not have to hang heavy curtains over the window and keep them closed. Natural light is good and it is a 4th floor office so privacy is not an issue. Would sheers have any sound dampening effect over the window?

I am going to put foam insulation over the door vent and bring in a white noise machine to set in the corridor. If I can deaden the accoustics of the room sufficiently, those two additional measures should insure that people in the corridor can not hear what is being said in the office. The only office next to mine is another psychotherapist, and we aren't there on the same days, so I'm not concerned about that.

Will appreciate any sharing of knowledge or experience.

Janie


01 Nov 13 - 05:15 PM (#3572066)
Subject: RE: Help with Room Accoustics
From: Janie

Should add that furnishings are sparse and while I will gradually add some more furniture there will never be a plethora of upholstered furniture to absorb sound.


01 Nov 13 - 06:01 PM (#3572072)
Subject: RE: Help with Room Accoustics
From: JohnInKansas

The steps you've indicated should all be of some help, although it's difficult to say which ones will help most or how much help any of them will provide.

One additional thing that could reduce "echo," a problem in many mostly empty spaces, would be addition of "furniture" in the room, even to the point of a bit of "clutter." You might be able to find a cheap sofa and stuffed chair or two at one of the charity shops (vets, salvation army, etc.) and if they're not too nice you could locate them so nobody would be inclined to sit on them while you're working. Of course you won't want your office to look like you filled it with a fork lift, but not everything has to have an obvious function for what you're doing when the clients are there(?). You can pretend you do "other stuff" there too, even if you don't.

Even hard surfaced furniture, if spaced so that it doesn't just make a new wall, can help break up the acoustic space. If you need more than one filing cabinet, set them so there's at least a few inches between them so they aren't a single surface to reflect sound. The "cavity" between them should help break up the sound.

For musical acoustics, heavier wall hangings would probably be better, but for conversational noise the weight of any fabric coverings shouldn't make a lot of difference, as long as they're fairly "limp." A curtain that hangs an inch or two away from the wall will usually work better than if it's flat up against a hard backing surface. Even "Venitian blinds" (slatted) left a little open can provide some damping of echo effects, and might be better for sound control than solid sheet blinds or even heavy curtains, and could still let some light - and air - through the window.

First thoughts only. We'll see what others have to suggest.

John


01 Nov 13 - 06:27 PM (#3572079)
Subject: RE: Help with Room Accoustics
From: maeve

Cork boards, cork blocks, etc can be found for little money and will provide both information and artwork display space. Woven sisal rugs can be used similarly. A quilt hung as John suggests will act similarly, and could also be backed with lightweight, preferably fire resistant blankets or denim insulation batts (class 1 fire rating) - just pin/baste them together before hanging.

A few pillows in appealing colors will help as well as enhance comfort and appeal (large used polarfleece-type pullovers can be altered to make fine covers that are also soft and friendly... and washable.) Cork also very fire resistant) panels may be helpful to mount on the inside of your door.

There are those of us who would be delighted to lend a hand once you decide what you need.


01 Nov 13 - 07:31 PM (#3572096)
Subject: RE: Help with Room Accoustics
From: JohnInKansas

There is quite a lot of information on how to control sound in auditoriums and other large spaces, and some of it is even helpful.

There are some differences between best methods for controlling sound in office spaces and what works best in an auditorium (or recording room). Large empty spaces are generally a more difficult problem than smaller ones, and the 15 ft square area with 10 ft ceilings and marble floors is sort of at a borderline.

One possible approach would be something like is done in some large offices, where "cubicles" are set up to provide some separation and "privacy"** for individual work areas. Setting up an "interview cubicle" with semi-partitions, where you could do the counselling/therapy with some attenuation of how much sound gets out into the larger room, and hence how much gets outside your space might be fairly simply done. A separate "conversation area" in the rest of the large room would give at least the appearance of a reason for having enough furniture to help attenuate how much sound gets from the whole area out into the rest of the world.

Folding screens, a. la. Oriental room dividers, could work about as well as the "office furniture" partitions that usually are bolted to the floor. Some "partition effect" might also be devised using the furniture layout. Depending on who your clients are, visual screening so that the therapy is exposed to fewer distractions might also be helpful. (Some kinds of people have more tendency to admire the furniture than to listen to the counsellor.)

For therapy or counselling, a more limited space, even if more space is available, may provide more "intimacy" in your relationship with the clients during a session. Whether that's useful would depend on the specifics of your working style(?).

If the sound can be "broken up" close to the source, the amount of attenuation needed to prevent it getting out of the larger space should be greatly reduced.

** privacy: (thread drift) Different people react differently to office layouts; but credible studies have shown that in a "bullpen" environment where everybody is out in the open, the workers may have more privacy than in cubicles or even private offices, and many employees feel "more free" out in the open. When the boss sees a "sea of heads" it's difficult to tell who is missing so it doesn't matter much if it sometimes happens to be YOU. If you have a cubicle, or office, an empty cube immediately identifies YOU and ONLY YOU, and "accountability" for absences is more likely to be perceived as being needed.

John


01 Nov 13 - 08:41 PM (#3572105)
Subject: RE: Help with Room Accoustics
From: Jack Campin

The classic low-budget way to make an anechoic space is to line the walls with soft cardboard egg boxes.


01 Nov 13 - 10:10 PM (#3572109)
Subject: RE: Help with Room Accoustics
From: JohnInKansas

Jack -

Cardboard egg boxes can sometimes help make a decent recording studio, but they don't work very well for a space where the sound is mostly conversation/communication.

For a recording studio, practice room, or auditorium, the goal is to prevent the loud noises you intend to make there from getting out at sufficient levels to annoy the neighbors.

For an office space, the first goal is to not have noises loud enough inside to leak out.

There are, of course subsequent steps in getting the final result wanted in either case.

For a studio, you likely would also want to absorb the sound at the wall so it doesn't echo back and drive your mics crazy. For an office a small reflecting surface close to the person speaking can sometimes reflect back enough to improve the clarity of what both the speaker and a nearby listener hear, with the possibility of reducing the tendency of the hearing impaired to "speak louder." In the latter case, the "echo" must come back before there's enough lag to make it sound like it's not part of the original speaking.

Some home architects, and "decorators" actually have paid at least nominal attention to acoustics at ordinary sound levels, although it's hard to find enough info all in one place to put together many basic principles, or to know when to use which ones.

John


02 Nov 13 - 03:08 AM (#3572125)
Subject: RE: Help with Room Accoustics
From: Abdul The Bul Bul

One point about covering the 'door vent'.....It's probably there to let air in. The office will be complying with local codes that require a certain number of air changes to the room. Very likely there will be a grille in the ceiling extracting stale air and that air needs to be replaced. You'll have to let it in somehow.
Al


02 Nov 13 - 04:09 AM (#3572129)
Subject: RE: Help with Room Accoustics
From: JohnInKansas

Since the building was apparently built without central AC, the door vents may have been required then to allow combustion air in or to prevent fuel fumes from accumulating if separate heaters were used in the individual rooms.

It's also possible that when central heating was later added, especially if a forced air system is used, that the air vents were added to let the stale air out when conditioned air is pumped in.

In either case, it would be advisable to ask the building management before blocking them, just to be sure that it doesn't prevent something from complying with codes or that you don't prevent something from working as intended.

It is possible to block reasonable noise levels while still allowing air flow, or perhaps an alternate venting could be provided where the noise that passes through wouldn't compromise privacy, if those vent areas are still needed.

Deadening the room so that minimal noise is produced inside it is generally better for an office space than producing a lot of noise that you have to prevent from getting out (unless one of the clients really needs to play a tuba as part of the therapy?).

Functionality, and practical limits on what can be done at reasonable cost, do need to be considered, regardless of how the problem is approached.

John


02 Nov 13 - 08:13 AM (#3572183)
Subject: RE: Help with Room Accoustics
From: Janie

Thanks for some very useful information!

Janie


02 Nov 13 - 06:50 PM (#3572291)
Subject: RE: Help with Room Accoustics
From: GUEST,Tony

Janie: we architects usually have to consider two aspects of acoustics: transmission of sound between rooms, and reverberation time (RT) within a room. It sounds like you have problems in both areas, but perhaps solving the RT problem will decrease the need to speak loudly, and then maybe the transmission problem won't be so bad.

Transmission is decreased by using heavy material in the wall and by having no openings in it. Sound can only move through a wall by creating waves in the material the wall is made of, i.e. by moving the material slightly. Moving heavier material uses up more energy, so less gets through. But if there are openings, even small ones, the sound will go through those freely. So a louver is a big problem, of course, and foam over it won't reduce sound transmission much because it's light and doesn't use up much energy. Gypsum board over it would reduce it much more, as long as it's sealed tightly to the door, but you'll be losing your ventilation; also, if that louver is your return-air grille, you'll be losing your heating and cooling. Air has to be allowed to leave, to make room for heated or cooled air to be blown in.

Reverberation means sound bouncing around in the room as it's repeatedly reflected off the surfaces, before it's eventually absorbed into the walls, either to pass through to other rooms or to be dissipated by the mass of the wall. The more times it bounces, the longer the RT. Very long RT is called echo. RT is decreased by using sound-absorbing materials on surfaces in the room, and it's decreased more as the area of sound-absorbing material increases, and also as the absorption rate of those materials increases.

Thin cloth has a very low sound-absorption rating. My guess is that it won't have much effect, even if you drape it over all the walls. Covering as much of the extremely reflective marble as you can will help a lot. What about the ceiling? If it's plaster, which is very reflective, can you glue acoustic tiles to it? Those have a very high absorption rating, and they're cheap and easy to install. That should have a big effect. And maybe glue them to wall surfaces, at least to the upper part of the wall.

By the way, the highest absorption rating any material can have is 1.0, which is defined as the absorption of an open window. So leaving the window open would decrease reverberation time more than anything you could put over the window, and it might solve the problems you might create by covering the louver.


02 Nov 13 - 07:53 PM (#3572308)
Subject: RE: Help with Room Accoustics
From: Janie

Thanks Tony. I do think cutting down on the RT is the first problem to tackle. Also realizing from your and John's posts that this will be an experimental and incremental process - which is good because I really need to spend no more than is necessary. This new location and addition to my part-time private practice is essentially a charity care practice. I won't make much money, but in order to afford to provide the service I need to keep costs down and insure it is at least "break even."

It seems I will need to ask some questions to find out if the door vent still serves any purpose. There is a forced air vent up near the ceiling but I don't otherwise see anything like a cold air return in the room. Thanks for the information re: gypsum board vs. foam insulation. I wonder if it would be feasible to have a piece of gypsum board framed that I could put up when I am in the office and remove otherwise? If the considerable reverb in the room can be sufficiently dampened I think it will be less of a problem for intelligible sound traveling outside of the room.

Sounds like (no pun intended) the first step is to carpet the marble floor. Eh?


02 Nov 13 - 09:21 PM (#3572335)
Subject: RE: Help with Room Accoustics
From: Ebbie

I too was thinking of folding screens. If you used 'throws' - perhaps doubled, or even small rugs, rather than commercially made sides on the screens - - it would add color and warmth to the area.

A small space enclosed with screens should 'trap' sound enough that clarity without echo is possible.

I have a small living room - perhaps 10 x 11 feet - but the other night when I hosted five musicians in it we all heard each other very clearly. Two of the more hearing-impaired said that for the first time they could hear all the words the others sang.


02 Nov 13 - 09:23 PM (#3572338)
Subject: RE: Help with Room Accoustics
From: GUEST,Tony

Yes, if you can carpet it all, even with a thin carpet, that should help a lot. But acoustic tile is cheaper than carpet. You can glue it to the plaster with construction adhesive, in tubes that you load in a caulking gun. Of course you'd need a tall stepladder.

If there's no return air grille in the room, then the return is through the door louver and along the corridor to another louver at the furnace room. They used to do that a lot. You could screw hooks into the door just above the louver and make a panel that hangs on them. It can be anything heavy. Try to get it to seal around the louver frame when it's in place, maybe with foam weatherstripping.


03 Nov 13 - 05:00 PM (#3572547)
Subject: RE: Help with Room Accoustics
From: Amos

Carpet stores often offer very low prices on offcut segments, which could be scattered around. The marble floor is a big culprit in bouncing soundwaves, I suspect. Craigslist might also be a source for really inexpensive throw rugs or area rugs.

A


03 Nov 13 - 07:35 PM (#3572573)
Subject: RE: Help with Room Accoustics
From: Janie

The building owners are not going to grant permission to glue acoustic tile anywhere, Tony, so carpet will definitely be the first step.

Good idea, Amos. Could possibly find a remnant and have it bound that would cover most of the floor. The alternative would be two 7x9 area rugs plus a couple of runners. Will start shopping around and doing some price comparisons.


03 Nov 13 - 08:49 PM (#3572595)
Subject: RE: Help with Room Accoustics
From: GUEST,leeneia

Presumably you, as a therapist, will not be raising your voice at people. It's the clients, who, stressed or ill, might be doing that. How about if they faced book cases filled with books? I'm sure they would be sound-absorbing.

Think back to every professor's, lawyer's or doctor's private office you have been in. Do they echo? No, because they are crammed with books, journals and pamphlets.

And it will be nice for you get books out of your home and have more room for yourself.

Also, set up the coat-rack so that clients talk towards it. Coats must be good sound-absorbers.
========
Are you sure the floor is real marble? That seems unlikely. Marble is expensive, slick, and likely to absorb stains.

Ask management if it isn't some modern substitute.


07 Nov 13 - 09:33 PM (#3573767)
Subject: RE: Help with Room Accoustics
From: GUEST,Tony

I'm surprised the landlord opposed it. They really should offer to pay for the material. Acoustic tile ceilings are almost universal in offices, for reasons that you can appreciate. It would make the space easier to rent in the future.