Acoustic Panel placement in a strange situation

[The Paulinator]

Here is the situation: My mother is a dental hygienist and the office she works in has a major problem. The individual rooms where they work on patients are sort of like cubicles in one larger room. The walls are only about 8 feet high, and the ceiling of the entire room is at about 9 feet on the east and west sides, and angles upwards towards the center, reaching an apex at probably 11 or 12 feet in the center, like an A-frame design. Also, the doors of all the cubicles are just openings with no actual doors, and the floors are all wood. According to my mom and the other employees, the noise reflects around so badly that everybody has to raise their voices to talk to their patients, and consequently it gets even HARDER to hear one another because everybody in the 9 cubicles is talking really loud. And they are able to easily hear the conversations of people in cubicles on opposite ends of the larger room.

I have been asked to see what I can do to help the situation, but to do so without adding anything to the tops of the walls, and to try to keep it looking unobtrusive, because it is a very nice office. I have talked extensively with the dentist who owns the place and we have decided that we should start somewhat small and add until we feel we have tames the problem enough, so we don't end up with a room dotted with acoustic panels that may not have been necessary.

Here is my question: It seems that one of the main reasons (besides all the other obvious ones, like short walls, no doors, and hardwood floors) this is so especially bad is that the ceiling right above each cubicle is angled in just such a way that almost all of the sound that hits it is going to be reflected out of the cubicle (I should add that these "cubicles" are about the same size as a room in any other dentist office, not any smaller as my wording might suggest). It is also worth noting that the hygienists are talking toward the floor, but the patients are talking straight at the ceiling, so some sounds are bouncing around the cubicle first, while others are basically meeting the ceiling with their primary reflection. In that case, would it be wiser for me to start by treating the ceiling with some absorptive panels to stop those reflections, or better to treat the individual cubicle to allow less noise to get to the ceiling in the first place. It is also a delicate decision because it would be much easier to hide acoustic panels places inside the rooms rather than on the ceiling.

Any thoughts?

[pjpoes]

Sound is going to reflect off of the ceiling at precisely the same angle it hit it at. You might find that means it's reflecting right back into another cubicle, maybe hitting the floor and bouncing back. You can see where this begins to snow ball.

I think one fix could be acoustic diffusers. They can be made to be quite attractive, while keeping the sound from bouncing around all the rooms.

What is the ceiling made of, can things be added to it?

Unfortunately problems like this can't be fixed cheaply, and it won't happen with one or two little changes, but it can be done in a way that looks good (but I think it will cost more). My opinion is that the best way to do this without spending too much and with the minimum of added items is with the aid of a professional room acoustics company who specialized in professional spaces. Generally such consultation is around 150 dollars an hour, but will give them the ability to model the room and simulate exactly what is causing the problem, and how best to fix it. Otherwise it's just speculation, which is the best way to end up with a room full of useless treatments.

I don't think that this problem would be fixed by simply adding absorptive materials, as the most they can do is lower the level, not eliminate it, and so will only marginally fix the problem, if at all. I think the types of devices which will help the most are going to be those designed for echo and flutter, such as those made by RPG.

[The Paulinator]

The ceiling is normal drywall, so it has even less dampening qualities than some other ceiling types might have, even if they are minimal. Things certainly can be done to the ceiling, as my original suggestion was to add a few acoustic panels above and slightly toward the center of the main room from the patient chair of each room.

I understand what you are saying about the use of a room acoustics company. I actually own a small AV installation company and have worked with these companies in the past in other professional areas I have done work for, like fitness centers. What I have found in the past is that what these companies ended up doing was very similar, if not identical, to what I would have done using my experience and knowledge in applying acoustic treatments to Home Theaters and such. I don't see the challenge here as being insurmountable for my own abilities, I was am just trying to make a decision as to where to start, not what to do once I have started. I tend to lean much more towards just starting with, and maybe ending with, unobtrusive treatments on the ceiling, as I think the rooms are a little too crowded with various tools, chairs, and varying levels of cabinetry (etc.) to be considered the real culprit when there is a gigantic flat plane right overhead. Actually, in writing this I sound to myself like I have made my decision and am just checking my work.

[pjpoes]

Can you make measurements to look at the reverberation in the room? That might help you to see how effective it is. I'm still reluctant to see the absorbative treatment's work on this particular problem. It would be the cheapest solution maybe, but I don't think the most effective. I'm actually thinking of something more like wood slats running the length of the ceiling, to break up and refract the reflections some.

I see no reason why you couldn't try your idea first though, it's easy enough to remove them if it doesn't work.

[The Paulinator]

Actually my first suggestion to him was related to what you said about the slats on the ceiling, but he said that was pretty much out of the question. But you are definitely right. I would have preferred something like that also.