Our Daughter has Acute Noise Sensitivity .....

[KenG]

due to Chronic Fatigue Syndrome. We need to sound proof her bedroom to the maximum extent possible.

She has a small house (wood construction with a peeked roof & plaster board walls) just out side the North East corner of Los Angeles in Eagle Rock.

The house is only about 800 Square feet and the her Bedroom is about 144 square feet.

The bedroom has windows on three walls. None of the windows face the street.

There is a new home going to start construction directly across the street.

Please advise on where to look for help.

Thank you very much in advance.

Ken

[Soundman2020]

Hi Ken, and welcome to the forum!

That's a rather unusual problem, but there are solutions. What you need to do is actually very similar to what we do to isolate music studios.

First, has her doctor indicated what the maximum sound level is that your daughter is able to handle without undue discomfort? The basis for isolating her room is to determine how much isolation is needed, and the basis for THAT is whatever level your doctor says is comfortable for her. If you don't know that level, you can determine it yourself by buying or borrowing a sound level meter, and actually measuring along with your daughter in various situations, so she can tell you what level she find acceptable.

The reason why this is so important is because there are various methods for isolating a room or building, and various construction materials for each method, so it is critical to define the right one. If you make this large investment in modifying her room to get high isolation, and then it isn't enough, that would be very sad as your daughter would still suffer with the high levels. And on the other hand, if you isolate it a lot MORE than is needed, then your daughter will be very comfortable, but you will have spent way more money than you had to. Because adding more isolation is actually an exponential function, not linear: Basically, each time you double the isolation level, it is going to cost you at least four times as much as the last time you doubled it. So it gets very expensive, very fast.

Thus, the need to accurately determine the level that your daughter finds comfortable.

To measure that level with a sound level meter, there's a couple of settings on the meter itself that are very important: One is to set it to "C" weighting, NOT to "A" weighting, and the other is to set it to "Slow" response. On most low-cost meters, there's usually a couple of switches that you slide to make these settings, or a button that toggles between the settings. It's very simple. To actually make the measurements, hold the meter out at arm's length away from your body, at chest height, and with the microphone tip angled upwards at about 60° or so, roughly. Make several measurements in various places, note down the decibel readings and your daughter's comment about each location and level on a piece of paper, then choose a target level that is consistent with her comfort.

While you have that meter, also go out by yourself to find a few local construction sites, and measure the levels of noise just outside those, at a similar distance to where your daughter's house is from the new construction. Try to measure when they are making a LOT of noise, with various types of tools, and note down the levels.

Now you have two sets of levels: the typical level of a construction sight, and the level that your daughter needs. The DIFFERENCE between those two levels is how much isolation (in decibels) you need for your daughter's bedroom. That's the level you need to aim for with the isolation plan.

But there's still one more level you need to determine: how much isolation the room is providing at present. Because you only really need to determine how much EXTRA isolation that room needs, beyond where it is now. So once again, take a series of measurements inside and outside at various times of day, with various noises going on (heavy traffic driving past, sirens, aircraft flying over, dogs barking, radios playing outside, people talking, etc.) The idea, once again, is to find out the DIFFERENCE between how loud a sound is outside the house, and how loud that same sound is heard inside your daughter's bedroom with the doors and windows closed.

With all of that information measured with the sound level meter, we can determine how much EXTRA isolation that room needs in order to keep your daughter comfortable.

Based on that, we can suggest the best method for modifying the bedroom so it does produce the right level of isolation.

This is a very interesting issue, and one where I'd love to help.


- Stuart -

[KenG]

Stuart;

Excellent very clear information!

We very much appreciate your interest and help.

We will get the a meter to measure the sound but....... we already know that she can only tolerate light whispers most of the time. So we need a very high high level of sound proofing. Neighbors lawn mowers ..... loud closing of doors..... garbage pickup all are intolerable for her (cause great pain). There are occasional helicopters but no fixed wing aircraft overhead.... The noise level of the construction site is not yet known since they are just about to start (and got delayed by the 2 inches of rain that we got Thursday).

Thanks!

Ken

[Soundman2020]

Hyperacusis is debilitating, and very real. Some people don't get just how painful it can be. My dad was a doctor, and my daughter is a doctor, so I do understand it a bit.

I'm not going to lie to you and say that isolating her room is going to be simple and cheap: it isn't. The high level of isolation that you are talking about can only be achieved with a lot of mass: heavy, thick building materials. Mass is the only way to stop sound effectively. Actually, it's a combination of mass and "damping", to be more technical, but the key is mass. The more isolation you need, then more mass you need, and this is where the unfortunate issue of exponential costs kicks in.

Let me give you a brief explanation...

The decibel scale is logarithmic, just like our ears are. Each time you go up ten points on the scale, that implies ten TIMES the amount of sound intensity. So for example if you look at a reading on the meter, and it shows 50 dB (decibels), then you measure another sound that shows 60 dB, that means that the second sound is actually ten times louder, in terms of sound power, but we humans will only hear it as twice as loud, subjectively. If you then measure yet another sound at 70 dB that one is 10 x 10 = 100 times louder than 50 dB, but we humans hear it as only four times louder. 80 dB is 10 x 10 x 10 = 1000 times louder, and we hear that as 8 times louder, subjectively. In fact, normal human hearing covers a range of about 3 millions times the sound power, from the quietest sound that we can barely perceive, to the loudest sound just before the threshold of pain, at about 120 dB (except for you daughter, who reaches that threshold of pain at a much, much lower level).

So that's how our ears work, and how sound power works. But the same issue applies to STOPPING sound. Each time you go up the scale ten points, you have to STOP ten times as much sound. And that's why you need a lot of mass to achieve high isolation.

To put this in perspective, and give you a sense of what we are going to have to deal with to isolate your daughter's room: A typical house wall will give you about 30 dB of isolation (also called "transmission loss" in technical jargon), or maybe 35 dB if you are lucky. A soft whisper (what your daughter considers acceptable) would barely register on a typical sound level meter, since they are designed to measure loud sounds, not quiet ones, but it would be at a level of maybe 35 dB. So, if a whisper is 35 dB, and your house wall gets you 30 dB of isolation, then a sound outside at 65 dB would be knocked down to an acceptable level inside, for your daughter. Whisper level. 65 dB is not very loud for most people: that's roughly the level of normal conversation between two people. So your house wall is about good enough to make that normal conversation outside, acceptable to your daughter inside. But a lawnmower running outside could easily hit 85 dB, and since the house wall only knocks off 30 dB, it would sound like 55 dB inside the room. Fine for most people, but painful for your daughter. In order to make that lawnmower acceptable, we would have to improve the isolation of the house by an additional 20 dB. In other words, your walls, doors, windows, roof, floor, electrical system and ventilation system would all need to be modified so that they provide an extra 20 dB of isolation. So instead of getting 30 dB you would be getting 50 dB isolation. That is possible, but you need to be aware of what I said earlier about the "ten times" problem. Improving the isolation by 20 dB means that we have to block ONE HUNDRED TIMES more sound power than your house is blocking at present (10 x 10), because we are moving up ten points from 30 to 40, then another ten points from 40 to 50. If you needed to get to 60 dB isolation (so that a sound at 95 dB outside would not bother your daughter inside), that implies blocking a thousand times more sound than the wall is blocking right now (10 x 10 x 10 =1000).

OK, so I have painted a bleak picture here, but let me say that it IS possible to get a level of 60 dB isolation. It can be done. That's the level typically attained by a really good home studio, and many people here on the forum, and many of my clients, have built their studios to that level.

That's about as far as you can go in a typical house. Getting higher levels than that requires far more complex techniques that are beyond the reach of most home studio builders.

So that's the good news: it is possible to get high isolation. The bad news is that it is not easy, and not cheap, for the reasons given above: You need a lot of mass to do it: heavy, thick building materials. And those are expensive. This is why it is very important to define the level that you NEED very well: because every extra decibel will cost you more and more money.

They simplest way to get high isolation at a reasonable cost is by using the technique that is commonly called "room within a room". That's the lowest cost method, and is the way that most studios are isolated (even professional studios). What this means is that within your daughter's existing room, you will need to build a second room: so just next to each existing wall, you build a new wall, maybe an inch away, then you put a new ceiling on top of those new walls, also about an inch way from the existing ceiling. For each window in the original room, you put in a second window in the new wall, directly opposite the original window. The same for the doors.

That's the basic concept, but there's other things you need to do to make this work. It's not quite as simple as just putting up a stud frame and hanging drywall on it.

This method uses the least amount of mass: you still need a lot of mass, but far less than with other methods.

So that's basically what you will need to do to get high isolation. There are no shortcuts, or magic materials, unfortunately. There are simpler systems that can get you some extra isolation yes, but for your case you need very high levels, and those techniques won't go far enough.

However, before deciding on the details of this method it would help to know what frequencies your daughter is most sensitive to: Is it high frequencies, or low frequencies? In musical terms, does she suffer more from a cymbal clashing, or a big bass drum being hit hard? That's very important to know as well: it's a lot easier to isolate for high frequencies, than it is for low frequencies.

Anyway, get that meter and do the tests, then we can help you put together your plan. You can buy a decent meter for around US$ 100 or so on e-Bay, Amazon, or at most large music stores or sound equipment stores. Avoid getting one of the cheap Chinese meters that are flooding the market at present, for under US$ 50 or so; they are just toys, and not accurate at all. Get a decent one, such as Galaxy or Extech.

- Stuart -

[KenG]

You have been amazing!

That is a LOT to consider.

I just looked and Amazon has Extech 407730 Digital Sound Level Meter 40-130dB ........ would that meter do the job?

THANKS,

Ken

[KenG]

One additional very important fact..... Daughter also became hyper sensitive to EMF..... so no WiFi..... or computers or microwave....

Thanks,

Ken

[Soundman2020]

I just looked and Amazon has Extech 407730 Digital Sound Level Meter 40-130dB ........ would that meter do the job?

That wold be excellent. That's a very decent meter at a reasonable price.

- Stuart -

[DanDan]

My sympathies. Just some alt/additional notes and suggestions. I note that light whispers are OK but all of the troublesome examples are both loud and primarily LF.
Odd isn't it, the ear is physically most sensitive in the 3-5KHz range.
I often use iPhone Sound Level Meters in preference to trotting out the B&K. Waving a big meter about in public or in a nightclub can be inadvisable. Also a more or less invisible meter might de-emphasise attention in our case. I have dBMeter, SoundMeter, LogSPL, NOSH SLM. They are all good in different ways, and all would work for your comparative situation. Mine are all within a dB or two of my BK, and most can be tweaked to be exactly the same.
A PMIC would up the standard a bit, giving you a pretty much Calibrated SPL and decently Flat FR on a phone.
A UMIK and computer would allow investigation of Spectra and many other facets.
'Sonic perfume' can be therapeutic and well, nice. Masking noise. You can find all sorts of masking audio files, rain, waves, babbling brook.
An actual water feature, a little fountain or flowing thing, can be very soothing, and hydrating.
I am assuming an ENT is at work here, and I would suggest a second opinion can only be beneficial.
DD