Hi! I have no experience in sound but I need to set up and experiment (or recommend hardware for it). We work in a hospital and each patient in this experiment should be exposed to a sound of at most 130 dB (I know it's really high but that's what I was told). We need to control the loudness in some way that let us change it in another experiment to 120 dB, 100 dB, 50 dB, etc.
We just have a Windows XP PC and no headphones, speakers, nothing.. I need to recommend them the best/cheaper solution (or any solution please :D )

Hi! I have no experience in sound but I need to set up and experiment (or recommend hardware for it). We work in a hospital and each patient in this experiment should be exposed to a sound of at most 130 dB (I know it's really high but that's what I was told). We need to control the loudness in some way that let us change it in another experiment to 120 dB, 100 dB, 50 dB, etc.
We just have a Windows XP PC and no headphones, speakers, nothing.. I need to recommend them the best/cheaper solution (or any solution please :D )

If a hospital purposely exposes patients to 130db it likely won't be in business very long, and rightly so. This is dangerous.

120 dB is the upper limit to hearing, 130 dB crosses into the pain threshold. Aren't our insurance rates high enough without more malpractice lawsuits? Hire an acoustician for your experiments who knows what they are doing - and they will avoid exposing you to any such liability (by refusing to play such a sound)

If a hospital purposely exposes patients to 130db it likely won't be in business very long, and rightly so. This is dangerous.

+1, what is the purpose, to get patients to pay their bills ?

130 dB? :o

are you trying to pop the patients ear drums? Hospital?

****This smells of BS to me!****

Hi! I have no experience in sound but I need to set up and experiment (or recommend hardware for it). We work in a hospital and each patient in this experiment should be exposed to a sound of at most 130 dB (I know it's really high but that's what I was told). We need to control the loudness in some way that let us change it in another experiment to 120 dB, 100 dB, 50 dB, etc.
We just have a Windows XP PC and no headphones, speakers, nothing.. I need to recommend them the best/cheaper solution (or any solution please :D )

Contact a hearing specialist within the hospital to help out with the exposure limits. While it seems you are looking for short term sounds, you have to consider the NIOSH exposure limits in the work. The REL (Recommended Exposure Limits) is normalized to 85 dBA for an 8 hour workday. Levels above this are considered hazardous (that meaning above the limit for 8 hours of constant exposure.).

Here's a link to the NIOSH Page..

http://www.cdc.gov/niosh/docs/98-126/chap1.html

Table 1-1 shows roughly how long one can be exposed to a spl without exceeding the threshold which requires hearing protection. 130 dBA, as you can see, falls into the less than one second category. While this chart is rather coarse at that end of the scale, 140 dBA from what I recall, was allowed as long as exposure didn't exceed 110 milliseconds (but don't take my word for this).. Further googling may help you out with the 130dBA range.

The other posters may not be exactly correct with limits and all, but they are all certainly correct that these levels are not to be trifled with (for all the right reasons). Seek the guidance of a qualified medical hearing specialist for this one..

At the very least, the system MUST be power and time limited to guarantee no overexposure occurs..

Cheers, John

The guy is selling earing aid also as a side line :-)

2 days ago came to talk to me 2 doctors from the research lab, one of them came from Boston (we are in Barcelona) just to start the set up of this kind of audio experiments.

As you can imagine I cannot start to question them about the 130 dB, I suppose they gave me this as an upper limmit, they won't be exposing patients to that kind of loudness. And if they would that is not my problem.

I need to give them just one suggestion about the hardware requirements to set up this:
Generate a sound and control the sound loudness, in principle don't worry about the duration.

I have no hardware to support this loudness and I really don't know what to do. I was suggested to use an Analog Display Sound Level Noise Meter
(I'm not allowed to post the url in the forum)
it's only 30$ and looks very good for measuring the dB.

But what kind of hardware do I need to achieve an output up to 130dB and control it? I mean: up to 130, but if they want 100dB achieve an output of 100, do I need a line array of 2000$?

What kind of budget are we talking about? 20 ?200 or 2000?

Say you used 98Db speakers, with sufficient power handling. And say we only need 130Db one meter away.

1 watt -> 98Db
2 -> 101
4 -> 104
8 -> 107 (etc)
...
32 -> 113
...
512 -> 121
...
2048 -> 131Db

Basically, your output is 98 + 3 * log(x) / log(2) [you would have to double check my math]. x is the power multiple.

I would guess you are looking at 2000+ watts, and speakers with the proper power handling. I don't know how that works out once you start adding more speakers and using multiple amps. I would guess the Sound Reinforcement Handbook would cover that.

Any competent sound reinforcement company should be able to give you a quote for a system that can hit 130Db.

130db at what frequencies?

Hi! I have no experience in sound but I need to set up and experiment (or recommend hardware for it). We work in a hospital and each patient in this experiment should be exposed to a sound of at most 130 dB (I know it's really high but that's what I was told). We need to control the loudness in some way that let us change it in another experiment to 120 dB, 100 dB, 50 dB, etc.
We just have a Windows XP PC and no headphones, speakers, nothing.. I need to recommend them the best/cheaper solution (or any solution please :D )

I think the doctors need to find somebody with experience to help.

If you insist on doing this yourself, good for you, you need to get more information.
Do they want speakers or headphones? Single tone, or broad band?

The way I read this is they do NOT want equipment capable of more than 130 db. Good thing. But even 120db is very loud. You will need a way to measure
volume at listening position - without being there for too long, if at all.

Talk to the doctors, talk to staff who have helped them before. Talk to medical audio experts. Most people here are hobby people. You need to
either become an expert, or find one.

You could easily make 120-130 db in a small closet with big efficient speakers. But I suspect the doctors want to do more than just expose their victims (I mean patients) to loud noise.

As you can imagine I cannot start to question them about the 130 dB, I suppose they gave me this as an upper limmit, they won't be exposing patients to that kind of loudness. And if they would that is not my problem.



Wrong - if you provide equipment capable of 130dB knowing it will be used in the presence of human ears - it IS your problem. 'Not my problem' is NOT a valid lawsuit defense....

I have permanant ear damage from a Motley Crue concert (at night I sometimes have ringing in my ears), which makes me a bit sensitive to the topic of overly loud sound systems. I find that to be a scary number too, but I find it hard to believe these Doctors are incompetent, though that's not unhead of.

Say you used 98Db speakers, with sufficient power handling. And say we only need 130Db one meter away.


Say you don't. Wave guides which operate into a smaller acoustic space can easily be 105dB sensitive, so getting 130dB takes only a bit over 300W.


Any competent sound reinforcement company should be able to give you a quote for a system that can hit 130Db.

I realize that we may be having a language barrier problem, but this whole thing seems so fishy I can't believe it's real. Some doctors from a research lab want to come to Spain to blast patients there with 130 dB signal of some sort? And they don't have their own equipment to do this? And a hospital in Spain is just going to let this type of thing happen? I don't think so...

I realize that we may be having a language barrier problem, but this whole thing seems so fishy I can't believe it's real. Some doctors from a research lab want to come to Spain to blast patients there with 130 dB signal of some sort? And they don't have their own equipment to do this? And a hospital in Spain is just going to let this type of thing happen? I don't think so...


I do have to agree that it is curious for a person with (by own admission) no experience, and only a PC running Win XP, being asked to come up with an equipment list for such a project.

Perhaps gunfire?

Table 3. CENTERFIRE PISTOL DATA (http://www.freehearingtest.com/hia_gunfirenoise.shtml)

.25 ACP 155.0 dB
.32 LONG 152.4 dB
.32 ACP 153.5 dB
.380 157.7 dB
9mm 159.8 dB
.38 S&W 153.5 dB
.38 Spl 156.3 dB
.357 Mag 164.3 dB
.41 Mag 163.2 dB
.44 Spl 155.9 dB
.45 ACP 157.0 dB
.45 COLT 154.7 dB


Use this calculator (http://myhometheater.homestead.com/splcalculator.html)to determine what amp/speaker combination you will need for your target SPL

Use this calculator to determine the loss with increasing distance.

http://www.sengpielaudio.com/calculator-distance.htm

Use a Google to find yourself a good legal advisor. Utilice un Google para encontrarse un buen asesor jurídico
:rolleyes:

aleplgr

Spain/España? :)

130 decibele es lo mas alot que nesesitan o quieren sustener 130 decibeles? Hay diferencia entre los dos. :)

SORRY everybody, it's my fault, they won't expose patients to 130 dB, that's an upper bound they won't reach.
Now I was told that up to 110 dB is the loudest case.
SORRY It was a misunderstood I rushed to ask here and everywhere without checking the real values of dB they will reach.
Now I found some headphones that reach 110

but how could I actual know the real dB I'm delivering at a certain time?
SORRY and EXCUSES again.

You could use a model head with calibrated microphones in the ear canal. This sort of set up is often used by reviewers and manufacturers.

You can also use an SPL meter, even the cheap ones from RS, to measure the SPL by tightly coupling it to the earpiece. Play signals at various gain settings and mark the volume control with the dB levels you need, e.g., raise or lower the gain until you get 60 dB and mark that setting, then increase the gain until you get 70 db and so on. Or you can measure the voltage across the headphone leads at each target volume level and make a table of settings.

If you can learn the efficiency (sometimes called sensitivity) of the headphones (by reading the specifications or asking the manufacturer), that is, what sound pressure level they can output for some reference leve input you can calculate the approximate SPL by measuring the voltage across the headphone leads at any given volume setting. The sensitivity or efficiency tells you what SPL is reached for a specified input signal level and sometimes at a specified frequency.

First, make sure you create the appropriate room for this. It needs to be both damped and insulated to get accurate frequency response (for measurements) and not blow away the surrounding offices.

Second, there may be a difference between "whole room" noise levels, and "headphone" levels. I'm assuming you're looking for "whole room."

Third, what you want to do won't be cheap. The equipment you'll need will be heavy enough to need reinforcement in the room where you'll use it.

Fourth, make sure you get someone local, who knows that stuff, involved. I would suggest contacting the Spanish chapter of the AES to ask for references:
http://www.aes.org/sections/view.cfm?section=106

To reach those levels with appropriate frequency control and low distortion, I recommend looking at the following speakers:
http://www.genelec.com/1036a/specs/
You will also need an accurate SPL meter/analyzer. Make sure it can do 130 dB without clipping, which the cheaper stuff probably can't handle!