History of the Loudspeakers

!±8± History of the Loudspeakers

A loudspeaker, speaker, or speaker system is an electromechanical transducer that converts an electrical signal. The term loudspeaker can refer to an individual device or driver, and a complete system consisting of an enclosure corporating one or more drivers and additional electronics.

Loudspeakers are the most variable elements in any audio system, and are responsible for marked audible differences between otherwise identical sound systems. Loudspeaker performance or accuracy in reproducing a signal without adding distortion is significantly poorer than that of other audio equipments.

Some important men who made history

Ernst W. Siemens was the first to describe the dynamic or moving coil transducer, with a circular coil of wire in a magnetic field and supported so that it could move axially. He filed his U. S. patent application for a Magneto electric Apparatus for obtaining the mechanical movement of an electrical coil by electrical currents transmitted through it was granted patent No.149797 on April 14, 1874.

Oliver Lodge filed for British patent No.9712 on Apr. 27, 1898, for an improved loudspeaker with nonmagnetic spacers to keep the air gap between the inner and outer poles of a moving coil transducer. This was the same year he applied for a patent on his famous radio tuner.

Thomas Edison was issued a British patent during 1881, for a system using compressed air as an amplifying mechanism for his early cylinder phonographs, but he ultimately settled for the familiar metal horn driven by a membrane attached to the stylus.

Harold Arnold around 1925 began program at Bell Labs to improve phonographic sound recording. The first priority was the electronic amplifier using the new vacuum tube, second was the microphone, and third was the loudspeaker that would improve the balanced armature units developed for public address.

Bell Laboratories in 1931 developed the two way loudspeakers, called divided range for the demonstration by H. A. Frederick of vertically cut records. The high frequencies were replaced by a small horn with a frequency response of 3000 to 13,000 hz, and the low frequencies by a 12 inch dynamic cone direct radiator unit with a frequency response within 5db from 50 to 10,000 hz.

How the loudspeakers used to work

The first loudspeakers used electromagnets because large, powerful permanent magnets were not available at reasonable cost.

The coil of an electromagnet, called a field coil, was energized by current through a second pair of connections to the driver. This winding usually served a dual role, acting also as a choke coil filtering the power supply of the amplifier to which the loudspeaker was connected.

AC ripple in the current was attenuated by the action of passing through the choke coil. However, AC line frequencies tended to modulate the audio signal being sent to the voice coil and added to the audible hum of a powered up sound reproduction device.

The quality of loudspeaker systems until the 1950s was, by modern standards, poor. Continuous developments in enclosure design and materials have led to the significant audible improvements. The most notable improvements in modern speakers are improvements in cone materials, the introduction of higher temperature adhesives, improved permanent magnet materials, improved measurement techniques, computer aided design and finite element analysis.

History of the Loudspeakers

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8 Ways To Lose Facial Fat

!±8± 8 Ways To Lose Facial Fat

Want to lose fat in your face? Unhappy with that fat chin? Feel like those fat cheeks are making you look "chipmunky?"

First, let's acknowledge that spot reduction of fat, through exercise or dieting anyway, is not possible. It would be nice if we could target our problem areas -- thighs, a spare tire, flabby arms, or in this case a chubby face -- and concentrate our efforts on melting the fat from those specific places. Nice, but not realistic.

That doesn't mean the situation is hopeless. Here are all the ways that I am aware of for helping to get rid of a fat face, or at least diminish its plump appearance.

1. Exercise and diet to lose overall body fat.

When we lose weight we tend to lose fat from over our whole bodies. If you are overweight, then sensible dieting along with a regular cardiovascular workout will burn fat from all areas, including your face. For some people the difference will be dramatic, for others less so, but all should enjoy some improvement in facial appearance. Remember: Spot fat loss through exercise isn't possible, but fat loss is.

2. Drink more water.

Drinking eight big glasses of water a day has been proven to aid in weight loss. Sometimes when we think we're hungry, our body is actually just thirsty. Drinking lots of water can take the edge off our "hunger" and keep us from overeating, thus helping us to lose fat.

There's another reason to drink water, though. Sometimes a fat looking (or puffy) face is caused by bloating, the body's retention of fluid as a response to being water deprived. If you're a woman--especially if you've just come through a pregnancy or are experiencing menopause--this could be part of the problem. So drink up! Good ol' H20, that is.

3. Firm up your face.

Some people swear by facial exercise; others consider it silly and question it effectiveness. It won't hurt to try it for a few weeks or a couple of months to see if it works for you. Remember, your aim here is to tighten and firm your skin, not to try to spot-reduce the underlying fat (since that's impossible anyhow).

Here's an old one for firming up a double chin: Using the back (top) of your hand, slap/tap the bottom of your chin rapidly yet firmly. Do this often, whenever you think of it.

For cheeks: Sit. Relax. Smile, keeping your lips closed. Now suck in your cheeks and hold them in while you count 8 seconds. Relax and repeat at least ten times. This is a good one to do while driving, as it requires no hands to perform. Another exercise for your cheeks is simply to smile as wide as you can (lips closed) as you imagine you are trying to touch your ears with the corners of your mouth.

4. Get older.

This is the easiest way of all to lose fat from the face -- it only requires patience!

If you're in your teens, twenties or even thirties, your roundish face might be caused by baby fat that has yet to melt. Give it some time, and meanwhile be sure to work on reducing your overall body fat if need be. As people age they tend to lose a lot of their facial fat. The drawback to this natural process is that by their fifties, some people end up with excessively gaunt looking faces. That's a problem to tackle another day, though.

5. Lose face fat the magician's way.

Magicians use misdirection to deceive. You can "lose" the fat in your face the same way -- by misdirecting the viewer's attention and by disguising the roundness.

Sorry, guys -- these are women-only subterfuges ... unless you are into makeup or have long hair. And so, ladies ...

If you have a double chin you want to camouflage, I'm told that adding some blush along your jaw line will do the trick. Start from just below your ears and brush it all the way to your chin, making sure to blend. If you also put a spot of white powder on the tip of the chin for a highlight, the overall effect will be dramatically slimming.

Similarly, to make your face look thinner, just brush bronzer over your cheekbones and temples, as well as under your chin. Boost the effect with white-powder highlights on chin tip, cheeks, forehead and the bridge or your nose.

Finally, ask your hairdresser for a style that will either hide or draw attention away from a round face. Hairdressers are experts in knowing which styles are best for which face shapes.

6. One word: Ultrasound.

Ultrasound is increasingly being used for cosmetic purposes. A special ultrasound machine can be employed to send energy deep beneath the skin, where it liquifies underlying fat cells without harming tissue or nerve cells. The liquified fat is then expelled naturally by the body--or at least that's what proponents and practitioners of ultrasound therapy claim.

7. One other word: Liposuction.

Liposuction is more invasive than ultrasound therapy by itself. It can also be combined with ultrasound. As you probably know, liposuction involves making one or more small incisions in the skin, inserting tiny "vacuum hoses" and suctioning out the fat. It works particularly well on double chins and jowls, and can be used to "deflate" fat cheeks, too.

8. Two words: Cosmetic surgery.

Celebs do it. Average people do it. For some, results are stupendous. For a few, they're a nightmare. Botched jobs do happen. And in any case, facelifts and similar cosmetic procedures are expensive.

This article on ways to lose fat from the face wouldn't have been complete without mentioning ultrasound, liposuction and cosmetic surgery. I deliberately did not go into detail about them.

If you are considering having any costly or invasive procedure to reduce facial fat (or for any other purpose), you need to do your own due diligence. Talk to people who've had the same procedure. Research it through the Internet. Get your doctor's opinion, advice and perhaps a referral. Learn about costs, side effects, recovery time and possible complications. Most importantly, gain a realistic understanding of what the procedure can and cannot do for your appearance. That way you'll avoid disappointment.

8 Ways To Lose Facial Fat

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Peripheral Poly-Neuropathy - My Diagnosis

!±8± Peripheral Poly-Neuropathy - My Diagnosis

Living with neuropathy is not the easiest thing in the world. Especially if you had any kind of active life before the neuropathy took effect and changed everything. In my particular case I wasn't all that active in the first place. I spent most of my time sitting in front of the computer staring at a screen using the keyboard. So when my feet started tingling or my legs grew numb, I just thought I was sitting in my chair wrong and I cut off the blood flow and my legs or feet were going to sleep. It should have been a clue that after a while, they really didn't wake up.

Mine started out as a gradual feeling in my feet. They felt like they had just starting to wake up after falling asleep, as an example, from sitting in a chair too long. You know, that odd feeling that you get when they just start waking up and the tingling makes everything you feel, feel 10 times worse. When something touched my foot or I managed to step on something on the floor, the feeling was magnified by the tingling, making it feel much more intense.

As time passed, the tingling gave way to a slight numbness. Actually the tingling moved up my legs didn't causing the lower parts my shins to tingle. This wasn't near as bad so I didn't think much about it. Then the pain in my feet started. Whenever I walked my feet no longer felt numb, but like I was walking on a gravel road barefoot. Even when I had shoes on. It felt as though I could feel every piece of gravel underneath my foot. Even though I was wearing a shoe and a comfortable stock. The feeling grew more and more intense. Like each rock that I was stepping on was sticking in my foot almost leaving a bruise behind. Just keep in mind that I felt these "rocks" whether I was wearing shoes are not.

This is when I decided that it was time to go see a doctor and figure out exactly what was going on with me. I was having a hard time walking, because of the pain in my feet and I noticed that I was stumbling a lot more than I used to, mainly falling sideways and bumping into chairs, tables, and you name it. I had bruises and scratches all over my arms and my legs I couldn't tell you where they came from. Actually this part wasn't all that bad is kind of like being high without having taken the drugs!! But then, there were the scratches.

The first person I saw was my family doctor. He did a few quick tests on me and discovered that I had borderline type 2 diabetes, which he quickly put me on some medication for and that seemed to clear that up. The Doctor also decided that the neuropathy was caused by the diabetes, thinking that it was probably diabetic neuropathy. I did a little bit of research on the net (every doctors being the -- the informed patient) and I found that diabetic neuropathy only occurred in patients who had a long term, undiagnosed severe diabetic condition, one that was very much out of control. Now since I had only been diagnosed diabetes in January before, and this was about March, I personally determined that diabetic neuropathy was not cause. I mean after all we patience to know more than the doctors do right?

During my next doctor's visit I approached him about this and he said yes this was correct, that it usually came from a long-term undiagnosed diabetic condition that was uncontrolled and that this may not have been what it happen in my case. But he did state that sometimes people got the neuropathy from the delete diabetic condition without being long-term or uncontrolled. But the chances of that were very slight. So on my request; he referred me to a neurologist. He also noticed that my hormone levels for little bit out of whack so he referred me to an endocrinologist, as well to get that checked out.

To make a long story short (yeah right), the endocrinologist found that I had multiple goiters in my thyroid and I ended up going through surgery to take them out. Actually they took the entire thyroid out, which made me really happy. NOT! So now I'm stuck taking thyroid medication for the rest of my life. The one part about this that makes me happy was that they found a micro-carcinoma in one of the goiters. It was fully encapsulated and well-defined so they weren't concerned about it having spread anywhere else. The borders were well-defined, it only involved a cell or two, and they were able to get it all when they took it out. As a result they were sure that that they'd gotten the entire thing and the no further treatment would be necessary.

I then started seeing the neurologist who looked into my case and started running me through a battery of tests trying to figure out what I had. After numerous blood tests, making the jump off the table with needles and voltages, x-rays, brain scans, and MRI, and a few other tests I can't remember he eliminated lime disease, multiple sclerosis, diabetic neuropathy, and determined that the blood flow in my feet and legs was almost perfect. Basically he could find no reason for the neuropathy or why it would be progressing as it was. T'was then that we tried a little more invasive test in the hopes of finding out what was going on.

They set me up for a minor surgery and we did a nerve biopsy on my left foot. This involved taking a small piece of nerve out of the heel of the left foot. The doctors told me that this particular nerve was for feeling a very small portion of the heel of that foot and normally would not be used by anyone (the word "normally" always scares me). When the surgery took place, they were supposed to make a ¼" incision in the heel of my left foot. They ended up making a 3 inch incision because they couldn't find the nerve! Turns out it was literally too small for them to see easily. When they did remove it and finally sat down for the testing, the normal stuff they were supposed to have found was definitely not there! Instead, they found that the nerve had lost all of its myelin (the protein sheath that protects the nerve), and that the nerve itself had been destroyed! So, the nerve was dead, or at very most dying.

This confirmed the diagnosis of the "demyelinating peripheral poly neuropathy". Demyelinating means that my body is stripping the protein sheath also from my nerves, which exposes the nerves to the internal body, where the nerves short out causing the numbness and tingling feelings. Once the sheath has been stripped off completely, it is my belief that my body begins to attack the nerve itself destroying it resulting in the complete loss of feeling and eventually motor function. I've always knew I had an overactive immune system, I just never thought it would work against me.

The "peripheral" portion of the name refers to the fact that it's currently affecting only my extremities, the peripherals being my hands my feet, so between you and me lets hope it stays there and doesn't spread inward.

The "Poly" part of the conditioned me refers to the fact that both my motor and sensory nerves are being affected by the condition. This means that eventually I will lose control of my muscles themselves and I will end up in a wheelchair or worse. The worst-case scenario here would actually being losing control of my chest and/or rib area, causing me to have to go on life support for the rest of whatever. But I try not to think about that as the risk of this is very low.

I've noticed over a period of time that increased stress in the job and/or my personal life can cause the disease to either exacerbate the symptoms or to actually cause it to advance at a quicker rate than it would otherwise. This is what has been happening to me over the last three months or so. It is been a very stressful time at work, and the stress is showing itself in a rapid advancement of my symptoms. For example my hands, which didn't used to show any symptoms of the disease have gone from a tingling numbness on the back of the fingers to a downright pain in the tip of the fingers, which intensifies when any type of surface that has a texture is touched. The best way I can describe it is this-everyone in their life has burned the tip of their fingers on say a hot pan or on a soldering iron in my case, and it left a blister behind. This is how the ends my fingers feel. Like there are little blisters at the end of each one and when I apply any pressure, it causes the same type of pain, almost a burning sensation. Definitely not a pleasant feeling, especially for someone who types for a living, being a computer programmer and all.

The way I'm actually typing this right now is by using Dragon Naturally Speaking. I've got my headphones on with my microphone, and I'm talking quietly to my computer and it is typing everything that I am telling it to. It is a great innovation, however I'm still training it and so I have to go back and corrected quite often. It is getting better as I can see it is recognizing more and more of my words as I'm typing... or I should say as I'm talking. So eventually I won't have to do much correction in it at all.

My neurologist has classified me as having a "moderate/severe"case of neuropathy. He told me at one point after I was diagnosed with the condition, that I could (might, maybe, possibly) find out what was exactly causing it if I went out to Charlottesville and visited the University out there and called on a specialist - one that specialized in neuropathies and have him run some specialized tests. Problem is the insurance company wouldn't cover any of these tests, and the only thing it would tell me is where it came from, not how to fix it. So, seeing as how he couldn't tell me how to fix it and the fact that I have already spent ,000 in the last year visiting doctors trying to figure out what was going on, I decided that it wouldn't be worth it. So at that point, I just accepted the condition for what it is, and started taking as many drugs as I could to alleviate the symptoms so that life can go on.

At the moment I take Cymbalta and Wellbutrin for the pain and depression that comes along with it. I recently started Carbitral which is a generic form of Tegretol to try to help with some of the nerve pain as well. Carbitral seems to be doing a very good job. I don't have the stabbing pains running down my legs, arms and my hands that I used to have, although I do still have that little blistery feeling at the end of the fingers. I take Mirapex for restless leg syndrome, MetNX (actually a prescription vitamin complex) for nerve pain, Primadone for essential tremors, and last but not least, I still take Glucophage for my diabetes. I find it interesting that I take more pills in two mornings than most people I work with are old!!!

I also take all Altace form mild case of high blood pressure. I take Lipitor for high cholesterol, Tricor for high triglycerides. I mainly have to take these because I can't exercise properly in order to work my levels down properly. I would love to do free weights but without having proper feeling in my fingers I end up under the weights. I can't do walking because the more I walked the more my feet hurt and after a while I end up stumbling around like a drunk. I do also use a cane which helps me in my balance area so I don't stumble and do things as much which my arms and legs thank me greatly for. It is also allowed made to acquire a great collection of canes! Some of them even have swords and daggers in them! I don't use those much but I do know they're there! Oh, by the way -- just to add insult to injury I also see a therapist once a week to help me with the depression and in handling the chronic pain

Anyway, the stress at work has let up a little bit. So let's hope that the progression of the illness has as well. I'll keep taking the drugs as long as they make me feel better (At least I'm not on the painkillers I was last year). I am walking with a cane right now, that really doesn't bother at least I don't need two of them to keep me up right!!

And, as you've probably seen by now, being able to enter words without typing and hurting my fingers is both a boon and a bane. I have a lot to say that I can get out, but at the same time... VERRRYYY LOOONNGGG AAAAARRRRTIIIICLLLLLESSS!

Have a great life!

Peripheral Poly-Neuropathy - My Diagnosis

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