Life After Acoustic Trauma

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I also have noticed 5 Delaware; I try to eat at the little café across the street whenever I’m in the neighborhood (al dente?). In fact I was so impressed I checked out the el dorado space; that is when I learned it was way out of my price range. I’ve been trying to put together a little bit about the “gentrification” of urban Kansas City but the more I see the costs rising the more I’m worried that the developers will kill the movement before it can really get started.

I think everything in downtown KC is out of my price range now. While it’s nice to finally see more activity downtown, I’ve always wondered what planet these people are from who can afford to buy those places.

I *really* wonder who the hell the people are that someone thinks will be willing to pay $400,000+ for a one-bdrm condo (two bangers are starting $600,000+) across the street from my school in this dumpy downtown of a small town out here. That I don’t get at ALL. If I could spend $400,000 or more on a place to live, trust me: this would be one of the very LAST places I would look.

I love sleep. :) I am too old. My body revolts. Must….sleep! Although I still have no problems staying up way too late…

Avoid Rain. Befriend Locksmiths. Live Happy…

Tonight a classmate gave me an article she read in the October issue of Dwell magazine about el dorado’s new condo building in the River Market, 5 Delaware. This is the building on the corner of 5th & Delaware with the steel and wood exterior. I swear that every time I passed by that building, I commented (along with some of my former coworkers) how I loved the design. (Except for the higher blank wall along 5th as you walk toward the City Market, but I know that’s getting a little picky.)

Anyway, for any of you in KC who are interested…check it out. And remember this – things could always be worse. You could get stuck in the rain. You could lock yourself out of your own house in the rain. You could be stuck in the rain, locked out and get struck by lightening. You get the picture. Just be thankful that that’s umbrellas, locksmith roseville and, term, that cable that divers lightening to earth instead of through your body. The lesson: carry an umbrella, befriend a good locksmith and basically don’t go out when you might get struck by lightening.

Most of the time so far I feel very lucky to be in this situation at school and to have these opportunities, and I’m excited by all the new-to-me places to go and people to meet and things to learn. But I haven’t even been here a month yet, so I still feel homesick sometimes. (Friday was, for some reason, particularly bad. And I miss Kansas City sunsets desperately.)

Who knows, I may always feel a little homesick (funny….I just mistyped that and it came out homeiskc) even when I’m excited to be wherever I am. In some ways I’ve felt that way my whole life, so that would make sense.

It was just nice to have someone new surprise me with a bit of Kansas City tonight.

Types of Hearing Loss

Hearing loss is a treacherous thing. Sometimes it can happen instantly, sometimes it basically sneaks up on us without notice, gradually, slowly. Gradual loss of hearing is especially problematic because the issue is neither immediately noticed by people suffering it, nor is it typically simple to pinpoint the cause for it. That is, unless you work in an industry where high noise levels are a common occurrence. In that case, you are at risk of hearing damage if you don’t use protective hearing gear and will likely end up need to use any one of the types of hearing aid available today. Still, even most workers in such industries don’t notice the difference until some damage has already been done.

Simple Breakdown of Hearing Loss

There’s a large variety of potential causes for hearing loss. Some cases basically end in partial or complete hearing loss, depending on the cause. Hearing loss can simply be a side effect of medicine. Medicines that can potentially cause loss of hearing are commonly called ototoxic. For example, large quantities of aspirin can cause hearing loss, as well as some drugs commonly used during cemotherapy treatment. Certain diseases also cause hearing loss as a direct result. Otosclerosis causes a bony growth in your middle ear, disrupting the overall hearing process. Meniere’s disease can impact both hearing and balance in varying degrees. Certain types of tumors can affect some of the nerves responsible for hearing. Then there’s also general trauma and noise induced hearing loss.

Hearing Loss From Physical Trauma

Unlike most of the other hearing loss causes that we listed, trauma and noise induced hearing loss have external causes. Hearing loss from trauma is exactly as it sounds – it can occur as the result of actual physical trauma. This includes ruptured or pierced eardrums, fractured temporal bones and damage from sudden air pressure changes or very loud noises. The last two causes are something it has somewhat in common with noise induced hearing loss.

oise Induced Hearing Loss

Noise induced hearing loss is the most common and most treacherous. This is the type of hearing loss where people usually don’t even notice it until some form of irreparable damage has been done. Noise induced hearing loss occurs through long term or short term exposure to noise around or above 85 decibel. The higher the sound pressure level measured in decibel, the less it takes for a person to suffer some form of hearing loss, if they’re not using hearing protection gear. For example, workers in a factory environment that are exposed to noise at 85 decibel, several hours per day, would usually suffer from gradually worsening hearing loss. Protective gear prevents it, but higher noise levels require more protective measures. High decibel noise exposure impacts the microscopic hairs within our inner ears, which are are basically a core element for “translating” vibrations into nerve impulses, which we eventually hear as sounds. The higher the decibel rating, the more it is potentially damaging to those hairs. This is not limited to working environments though. For example, people that have been in the vicinity of thunder strikes, or even been hit by lightning, have suffered hearing loss due to the fact that a “thunderclap” is usually around 120 decibel. Simply put – loud noises are harmful, regardless of the source.

How Decibels Damage The Hearing

As one of our five most basic body senses, our hearing is one of our most important tools for daily life and work. It enables us to effectively communicate, hear events in the environment around us. It matters to us both in daily life and in work. Especially in the workplace. Unfortunately, most of us are not really aware exactly how sensitive our hearing is. If you travel to work by bus, simply look around you once and try seeing how many people have headphones on and how many have them set so loud that you can hear what they’re listening to. How “loud” a sound is for us is usually measured in decibels. However, there’s a difference between how we perceive the loudness of a sound in decibels and what decibels are actually used for as a measurement unit.

What are decibels?

Simply said, decibels are a measurement unit used to determine the intensity of a sound wave. Specifically, they are used to measure sound pressure. Now, you may think that “pressure” and “volume/loudness” don’t exactly have much to do with each other. It’s basically all about perception. The way our ears work is by converting vibrations in the air into nerve impulses. Those vibrations are actually just really quick variations in air pressure. Our ears have delicate components that perform such a feat, so to speak. In our inner ears, there is a chamber filled with liquid and lined with microscopic hairs that pick up those variations in sound pressure and translate them into nerve impulses. The “louder” the sound, the more it impacts those hairs – loud enough noises can even destroy them.

decibel chart

How can decibels damage our hearing?

To cut right to the chase – anything around or over 85 decibel has a chance to damage your hearing, provided exposure is long enough. The higher it is above that threshold, the less you need to be exposed to it to suffer hearing damage. A typical conversation occurs at around 60 decibel. A jet powered aircraft taking off 100 meters away from you is usually around 140 decibel. Gunshots from most small arms range from around 140 to almost 200 decibel. If someone were to fire off a handgun right next to your ear, you would suffer instant pain that would disable you, hearing loss (which might be permanent) from acoustic shock, tinnitus and possibly a ruptured eardrum accompanied with bleeding. To put it into perspective, military and police forces around the world use flashbangs, whose primary purpose is to basically temporarily disable targets with a loud bang.

Prevention

In order to protect yourself from potential hearing damage, you need hearing protection in any sufficiently loud work environment. Consider investing into protective ear plugs, caps or ear muffs. For example, shooting ranges have strict rules about using ear muffs or ear plugs while shooting. Keep it all in mind even when you’re just listening to music on your phone – most headphones are noise-capped at 85 decibel, but even listening through stock headphones at max volume for a long period of time has a chance to damage your hearing.

The Truth About Industrial Deafness

TinnitusWhile not too many people may be talking about it, industrial deafness is a serious job related injury which is a lot more frequent than you’d imagine. This is a type of deafness that will occur if someone spends too much time in phonic polluted environments, where the noises are created by the area where the work is performed or by equipment.

Due to many on the job injuries in the past, a regulation was passed that forces employers to make sure that the level of noise in a certain work environment will never exceed eighty decibels. If the noise goes over eighty decibels, it can pressure the eardrums and cause permanent hearing damage. Employers that don’t respect these rules will undoubtedly be held liable for any injuries employees sustain due to the dangerously loud environments they need to work in.

Common Industries

No matter the industry you may be working in, if you work in a noisy environment, then you run the risk of suffering hearing damage sooner or later. This includes all factory positions and construction jobs where loud equipment runs during production, different military positions, runways and airlines, recording studios, orchestras, but also musical fields.

Possible Problems

Even though industrial deafness may make some people believe they will go deaf, it’s not really like that. However, it is possible that they may suffer total or partial hearing loss in one ear or even both ears. Most of the times though, people will be diagnosed with tinnitus, which is a constant buzzing, ringing or roaring sound that goes in and out. Due to its nature, tinnitus makes it hard for some people to even have a conversations on the phone. If the condition is severe, then it may force employees to even apply for disability, while others will only lose certain abilities, such as driving for instance. While for most people this is a treatable condition, unfortunately it’s not reversible.

Protection

In order to avoid hearing damage, it’s always recommend that you wear proper hearing protection. So if you plan on going to a concert or maybe to a club, then you may want to always wear earplugs. While they’ll not completely block out the noise and you are still going to be able to hear, they can block those dangerous frequencies that can damage your hearing.

Compensation

For most people who work on construction sites or in loud environments, industrial deafness is quite a common injury. This means that employers are obligated by law to provide employees safe working conditions that will not cause them hearing loss. Sadly, not many employers meet their obligations and the consequences of their ignorance are usually suffered by the employees. Tinnitus has become something of an epidemic within certain industries, resulting in an increasing amount of compensation claims.

As with any other type of injury and condition out there, it’s better to prevent than cure. However, if you’re a victim of your employer’s negligence and have suffered hearing loss, then you may want to learn more about how you can get compensation for it. You can generally do this by hiring a lawyer, since he’s going to speed things up so you get compensated fast.

Workplace Deafness: Creating A Safe Working Environment

Noise induced hearing loss is caused by sounds that are too loud – it can be caused by loud sounds that last only for a brief time (an explosion, for instance) or by continuous exposure to loud sounds (loud workplace, for instance).

What are the signs of hearing loss?

The first signs of noise induced hearing loss workplace hearing loss(NIHL) often go unnoticed. People usually notice it when they are unable to understand what someone is saying to them when they are in a noisy room or on the phone or when they notice that they have to turn up the volume of the TV. Even though a person might not notice that their environment or activities are damaging their hearing, they could end up having issues with hearing in the future. Even though that damage might be only temporary, it could still have a negative effect on hearing many years later.

Although everyone has been exposed to harmful noises at some point in their lives, some people are more vulnerable than others are, especially if they work in an environment that is loud. Luckily, major steps towards a safer work environment have already been taken, with the Control of Noise at Work Regulations from 2005 being one of the latest achievements.

The duties of an employer

According to regulations, the employer is obliged to assess the risk to employees and take action to reduce any noise exposure that can result in occupational deafness. If employees work in an environment that might damage their hearing, the employer has to provide hearing protection, thereby avoiding workplace hearing loss.

Employees should not be kept in the dark either – they should be informed about the risks, and they also play an active role – they have to undergo proper training, and they have to be properly trained on how to avoid the risks.

The noise action levels are levels of noise in decibels that should not be exceeded in a working environment. It is the duty of every employer to make sure that those noise action levels are not exceeded. Lower exposure values are set at 80 decibels with peak pressure at 135 decibels. Upper exposure values are set at 85 decibels with peak sound pressure at 137 decibels. The limit that should not be exceeded is set to 87 decibels with peak pressure at 140 decibels.

Workplace requirements

An employer must make sure that his workplace meets the following prerequisites in order to keep his workers safe:

  • The noise exposure should be between the lower and upper noise action levels
  • The employer must ensure proper usage and maintenance of hearing protectors
  • Employees should receive training, information on how hearing protectors are used and how to properly care about them
  • The employees must be informed about the noise exposure, the risk of that exposure, what is being done to avoid the risk, how to use hearing protection
  • The employees must also be informed about their duties under the regulations of 2005 (learning how to minimise the risk, proper usage and storage of hearing protection and equipment, when to use it).

Once these regulations are in place, the workplace will be a safe environment, no matter how loud it might get.

The Benefits of Wearing Aural Safety Gear

Aural safety gear is a great way to reduce the risk of developing noise-induced hearing loss and occupational hearing loss. The best way to cut back on noise is to fix the source of it, but sometimes that isn’t an option. In these cases, you must do what you can to wear hearing protection in the form of aural safety gear in order to cut back on the amount of noise that the ears have to process. Aural safety gear should be worn if the decibels at your workplace go above 85 decibels to prevent hearing loss.

Types of Protection

Ear Plugs

Ear plugs are placed in the ear to block the ear canal and protect the ear from noise. They can be preformed and premolded or moldable, which are usually made of foam. Ear plugs can be sold in two formats, as reusable plugs or disposable ones. You can also order custom molded ear plugs. You can also get semi-insert ear plugs, with two ear plugs that are held in place over the ear canal ends by a headband that is rigid.

Pros of ear plugs:

  • They can be either one time use or a reusable pair, so you can have them when you need them or just use them one time without worrying about it.
  • More comfortable than defenders to some, depending on the person

Cons of ear plugs:

  • If the ear plugs do not fit, they will not protect like they need to.
  • Have to buy a new pair if you lose them
  • May be uncomfortable for some

Ear Defenders

640px-Chainsaw_helmetEar defenders are also known as ear muffs, and they are made up of soft ear cushions and sound-attenuating material that fits around the head and ear, with hard outer cups and held together by a headband that goes over the top of the head.

Pros of ear defenders:

  • Great noise protection
  • Easy to use

Cons of ear defenders:

  • They may hurt the ears if worn for too long.

Ear defenders are better worn at workplaces and when around high level decibel noise and are well suited to doing yard work around noisy machinery such as a leaf blower. Ear plugs are better for when attending a very loud concert, being at a bar for an extended period of time, or when you are a musician who wants to protect your ears from loud noise.

Why Protect Your Ears?

Protecting your ears is always preferable to exposing them to noise. Noise can consist of high decibels and cause damage that, if is accrued enough or is loud enough at one point in time, can eventually cause hearing loss and deafness. The ears have tiny hairs that translate vibrations into sounds. When a vibration is too intense and the sound is above 85 decibels, it can damage the tiny hairs and the cells will die inside the inner ear. Then the hearing is damaged to a great extent and can’t be restored back to the way it was. Protecting your ears with aural safety gear so that doesn’t happen is the best thing you can do to protect your hearing. Keep your senses intact  and use gear such as ear plugs and ear defenders to protect your ears. They are more sensitive and easily damaged than you may think, so keep them in good shape with the appropriate gear and always use proper protocol to keep your hearing protected.

Biology of the Middle Ear

The middle ear is the part of the ear that is internal to the eardrum, external to the inner ear’s oval window.. Found in mammals the middle ear has three ossicles, a hollow space in the middle ear called the tympanic cavity. The tympanic cavity is joined to the nasal cavity by the eustachian tube.

MiddleEar

Blausen.com staff. “Blausen gallery 2014”. Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762.

The middle ear’s main function is to transfer acoustic energy from waves of compression in the air to membrane waves in the cochlea’s fluid. Other animals have different middle ears that evolved. Early fossil tetrapods, reptiles, and birds possessing a single auditory ossicle, the columella, that connected with the eardrum directly and operating as a evolutionary derivative of a bone in fish ancestors called the “hyomandibula”, which supported the skull as well as brain case. Mammals have a unique middle ear with three ossicles that evolved independently of the single ossicle middle ears that other land vertebrate possessed during the Triassic period.

The Ossicles

The middle ear has three small bones called the ossicles. They are the malleus, the incus, and the stapes. They were given their Latin names according to their distinctive stapes. They are also known as the hammer, the anvil, and the stirrup. These ossicles mechanically convert the energy and vibrations in the ear drum and transfer sound energy from the ear drum to the cochlea’s oval window, where it becomes amplified pressure waves in the inner ear’s fluid using the hydraulic and lever principle..

The middle ear also contains two tiny muscles. The tensor tympani muscle is attached to the hammer and helps tune and protect the ear. The stapedius muscle is attached to the stirrup. This muscle contracts in response to a loud noise, making the chain of ossicles more rigid so that less sound is transmitted. This response, called the acoustic reflex, helps protect the delicate inner ear from sound damage.

Malleus

The malleus is merged with the eardrum and connects to the incus. The incus then connects to the stapes. The eardrum attaches to the malleus handle and the linear attachment smooths out chaotic motion at frequencies that are three kHz or higher, allowing the ear to respond over a wider frequency change linearly than with a point attachment. The malleus or hammer on the inside moves when sound makes the eardrum vibrate.

Incus

The incus connects to the stapes and the malleus. It pushes against the incus, or anvil during eardrum vibrations and the incus sends movements to the stapes.

Stapes

The incus connects to the stapes, or stirrup, where their vibrations introduce pressure waves to the inner ear. Then the stapes push on the inner ear’s fluid through the oval window of the cochlea.

The Tympanic Cavity

This is the hollow space in the middle ear, also known as the cavum tympani. This is a small cavity that surrounds the middle ear’s bones. It is separated by the eardrum and abuts the external auditory meatus.

The Eustachian Tube

This tube helps to join the tympanic cavity to the nasal cavity, the airway at the nose’s back(the nasopharynx). This lets the pressure between the middle ear and the throat equalize and allows outside air to come in behind the eardrum in the middle ear. The eustachian tube opens when you swallow and helps maintain equal pressure on either side of the ear drum as well as preventing fluid from accumulating. The eardrum can uncomfortably retract or bulge if pressure isn’t equal and in the process, distort hearing. Popping of the ears can relive ear drum pressure caused by sudden changes.

The Stapedius and Skeletal Muscles

These muscles may stiffen the ossicles’ movement. The stapedius is the smallest skeletal muscle the body has. It connects tot he scapes at the malleus’ base and is controlled by the medial pterygoid nerve. These muscles contract when they hear loud sounds which reduces the sound traveling to the inner ear. This process is called the Tympanic or acoustic reflex.

Biology of the Outer Ear

The outer ear is the external part of the ear. It is structurally divided into the pinna, or auricle, as well as the ear canal or auditory canal, known as the external auditory meatus, and the outer layer of the eardrum (the tympanic membrane). The outer ear gathers sound energy and focuses it on the tympanic membrane. The function of the outer ear is to collect sound and have it travel through the auditory canal to the tympanic membrane, or eardrum.

Photo by Anatomist90. CC-BY-SA-3.0

Photo by Anatomist90. CC-BY-SA-3.0

The pinna, or auricle, is the visible part of the outer ear and is made up of a thin plate of yellow and elastic cartilage and soft tissue, making it flexible while keeping its shape. This cartilage is covered with integument. It’s connected by ligaments and muscles to surrounding parts and to the external acoustic meatus by way of fibrous tissue. Some mammals can even move the pinna with their auriculares muscles for the purpose of hearing better from a certain direction. Humans cannot do this. The pinna collects the sound vibrations and is the part that guides vibrations to the ear canal and decide the source and direction of sound.

The ear canal or external auditory meatus. This part of the ear is a tube that runs through the middle ear, from the bottom of the auricula inward. It sends the vibrations to the tympanic cavity as well as amplifying frequencies from 3-12 kHz.

The tympanic membrane, or eardrum, is a thin and cone-shaped membrane separating the outer ear from the middle ear for humans and tetrapods. The function of the eardrum is to transmit the sound in the air to the middle ear’s ossicles to the fluid-filled cochlea, where it converts and amplifies vibration to vibration in fluid. The tympanic membrane consists of the upper region of the pars flaccida and pars tensa. The pars flaccida is fragile and has two layers, while the pars tensa region is larger and has the three layers of skin, fibrous tissue, and finally mucosa.

Intrinsic and Extrinsic Muscles

Intrinsic muscles of the outer ear include the helicis major, the helicis minor the tragicus, the antitragicus, the transverse muscle, and the oblique muscle. The helicis major is situated upon the helix’s anterior margin as a narrow vertical band that rises from below and from the spina helicis, inserting into the helix’s anterior border. The helicis minor covers the crus helicis and is an oblique fasciculus. The tragicus lies on the tragus’ lateral surface and is a short and flattened vertical band. The antitragicus rises from the antitragus’ outer part, inserting into the cauda helicis and antihelix. The transverse muscle consists of scattered tendinous and muscular fibers that extend from eminentia conchae to the prominence, situated on the pinna’s cranial surface. Lastly, the oblique muscle is made of a few fibers from the concha’s upper and back part to the convexity above and lays on the cranial surface.

Extrinsic muscles of the outer ear are made up of three muscles that go around the auricula and outer ear, the anterior auricular muscle, the superior auricular muscle, and the posterior auricular muscle. The superior is the largest muscle, and the anterior the smallest. These muscles can adjust the pinna’s directions, however it doesn’t apply as much to humans.

Biology of the Inner Ear

The inner ear is found in all vertebrates, with some variation of form. It is responsible for the senses of hearing and balance. It is structurally divided into the cochlea and the vestibular system. The cochlea is a spiral-shaped structure that senses sound waves and the vestibular system is a group of chambers which sense any disruption in equilibrium.

The Cochlea

Photo by OpenStax College. CC BY 3.0

Photo by OpenStax College. CC BY 3.0

The cochlea converts sound mechanical energy from the middle ear into nerve impulses, which are then sent to the brain through the vestibulocochlear nerve. The movements of the bones in the middle ear push on a membrane called the oval window, which moves the fluids inside the cochlea (called endolymph and perilymph). The pressure waves in these fluids stimulate tiny hair cells inside a sensory organ named the Organ of Cordi. Different frequencies stimulate specific portions of the cochlear spiral, allowing the brain to differentiate between sounds of different frequencies. In humans, this ranges from 20 Hz to 20,000 Hz, although the ability to sense higher frequencies decreases with age.

The Vestibular System

The vestibular system is responsible for the sensation of balance and equilibrium, and in conjunction with stretch receptors in the muscular system and joints, our sense of proprioception (body position, movement, and acceleration). It structurally broken down into several chambers filled with the same fluids as the cochlea. These are called the semicircular canals, the utricle, and the saccule. Tiny otoliths (literally “ear stones”, in Greek) in the fluid respond to gravity and changes in motion and stimulate hair cells, which send impulses down the vestibulocochlear nerve. The brain recognizes the impulses as motion and in concert with the visual system interprets what is happening.

The different structures sense different types of motion. The semicircular canals sense rotation. There are three canals, oriented in three different dimensions to be able to sense all types of rotation. One end of these canals opens onto the utricle and the other end has a structure called the osseous ampullae, which has sensory hair cells. When the head moves, the fluid lags a bit due to inertia and stimulates these cells. This stimulation only lasts a few seconds however, as the fluid soon catches up to the motion of the head. The utricle senses changes in horizontal movement, and the saccule does the same for vertical movements. There is evidence that the vestibular system has retained some ancestral sensitivity to sound waves of very low and very high frequencies which the cochlea cannot perceive.