Chris Jahn said:
Im sure we have all heard that if your ears are ringing after exposure to high db, that you have at that moment caused permanent hearing loss, and even more specifically you have lost that particular frequency that your hearing ring.
Anyone know how true all of this is? what does it really take to blow out your ears over time, or even in one shot?
Chris,
140db is about the threshhold for pain, and possibly permanent damage to the ears. A motley crue concert would probably be something close to that.
Another good establishment to look at is OSHEA. They determine what is safe in the workplace in terms of exposure to many kinds of things.
At 85-90 db, you're looking at about 8 hours of exposure without critical damage to your hearing. I would say that's maybe about as loud as a blow dryer, perhaps a little softer.
I highly encourage you to study the parts that make up the human ear and how they function. Quite frankly, it would be very ignorant for any engineer to pursue a career in audio if he's oblivious to the mechanisms that make his career possible. I hate to put it that way, but if you're careless about your hearing, then feel free to plan for early retirement. That's how serious the matter is.
You have to understand that your ears are resiliant, but they are highly sensitive, too. I'm going to lay out some facts that I've learned over the years from many different professionals in audio and hopefully you can learn to apply them effectively:
-In the process of hearing loss, when you don't have ringing, you will develope a gradual loss in higher frequencies first.
The usual range of hearing for human beings will be from 20hz to 20khz. Certain races (especially asian) can actually hear frequencies in the 30khz range.
Within time, with normal exposure to the noises in current society, you will be lucky to hear up to 15khz by the time you are 40.
The reason being is because of the hairs inside the snail (cochlea) of your ear. You have *tons* of hairs running inside there, each at varying lengths. Each length corresponds to different frequencies. When you are exposed to sound, they move about to create the vibrations that we translate into an audiable signal. When that's damaged, they lay flat and fail to stand up in thier natural position.
-Habits such as smoking ciggerettes, or marijuana put your ears at higher risks for ear damage.
When you smoke ciggerettes (as I am currently guilty of), you deprive your body of oxygen by inhaling carbon monoxide. The compounds within that carbon monoxide prevent the process of natural healing and protection to your hearing mechanism by restricting blood flow to your ears. Instead of getting a healthy amount of red blood cells to your ears, the carbon monoxide attach to the cells in your ear, restricting the red blood cells from supplying your ears with vital oxygen. The oxygen they need to protect against the noises you're exposed to. Your ears are suffocating (on a smaller level) in the way you would if you where trapped in a room with car exhaust fumes.
With marajuana smoke, it's a little different. When you're exposed to extremely loud noises, your ears naturally lock up to protect themselves from permanent damage.
That's why when you leave a loud venue, you may experience a temporary muffled quality to your hearing, before they go back to normal. That simply means your hears are locked up. It's kind of like a water lock.
However, when you smoke marajuana, that tends to relax that mechanism. It relaxes your ears to a point where they don't lock up as much, if at all. The result is like if that water lock never kicks in.
-One last fun fact is that the consumption of any food and beverage actually temporarily changes your hearing temporarily. When your stomach digests food, it needs blood to do so. Therefore, your body makes adjustments to get more blood in that region of your body.
So it's not uncommon to hear about highly critical engineers eating light while on the job.
