Noise-Induced Hearing Loss

Every day, we experience sound in our environment, such as the sounds from television and radio, household appliances, and traffic. Normally, we hear these sounds at safe levels that do not affect our hearing. However, when we are exposed to harmful noise—sounds that are too loud or loud sounds that last a long time—sensitive structures in our inner ear can be damaged, causing noise-induced hearing loss (NIHL). These sensitive structures, called hair cells, are small sensory cells that convert sound energy into electrical signals that travel to the brain. Once damaged, our hair cells cannot grow back.

People of all ages, including children, teens, young adults, and older people, can develop NIHL. Approximately 15 percent of Americans between the ages of 20 and 69—or 26 million Americans—have high frequency hearing loss that may have been caused by exposure to loud sounds or noise at work or in leisure activities. Recreational activities that can put someone at risk for NIHL include target shooting and hunting, snowmobile riding, woodworking and other hobbies, playing in a band, and attending rock concerts. Harmful noises at home may come from lawnmowers, leaf blowers, and shop tools.

NIHL is 100 percent preventable! All individuals should understand the hazards of noise and how to practice good hearing health in everyday life. To protect your hearing:

• Know which noises can cause damage (those at or above 85 decibels).
• Wear earplugs or other hearing protective devices when involved in a loud activity (special earplugs and earmuffs are available at hardware and sporting goods stores).
• Be alert to hazardous noise in the environment.
• Protect the ears of children who are too young to protect their own.
• Make family, friends, and colleagues aware of the hazards of noise.
• If you suspect hearing loss, have a medical examination by an otolaryngologist (a physician who specializes in diseases of the ears, nose, throat, head, and neck) and a hearing test by an audiologist (a health professional trained to measure and help individuals deal with hearing loss).

Hyperbaric therapy – another potential solution to hearing impairment

“Hyper” means increased and “baric” relates to pressure. Hyperbaric oxygen therapy (HBOT) thus refers to intermittent treatment of the entire body with 100-percent oxygen at greater than normal atmospheric pressures.

It is known that HBOT:

1) greatly increases oxygen concentration in all body tissues, even with reduced or blocked blood flow;

2) stimulates the growth of new blood vessels to locations with reduced circulation, improving blood flow to areas with arterial blockage;

3) causes a rebound arterial dilation after HBOT, resulting in an increased blood vessel diameter greater than when therapy began, improving blood flow to compromised organs;

4) stimulates an adaptive increase in superoxide dismutase (SOD), one of the body’s principal, internally produced antioxidants and free radical scavengers; and,

5) aids the treatment of infection by enhancing white blood cell action and potentiating germ-killing antibiotics.

HBOT increases oxygen pressure in the inner ear. Oxygen flows from areas of higher pressure to those of lower pressure. It has been shown there is a profound decrease in oxygenation of the cochlea during and after acoustic stress and in acute hearing loss. 

With an increase of the pressure of oxygen in the cochlea, it is possible to influence the sensory cells of the inner ear. These cells have no direct vascular supply and depend entirely on oxygen supplied by diffusion. An increase in oxygen pressure can compensate for oxygen deficiency caused by trauma and gives rise to biological mechanisms that are involved in functional recovery.

Most of the studies show that HBOT is most effective in reducing hearing loss and tinnitus in the first three months following hearing loss or acoustic trauma. Regarding hearing loss alone, an overview of clinical studies from Germany shows HBOT is effective in 50% of cases in reducing hearing loss by 20 dB or more. Approximately 11% have a full recovery.

Be in their shoes

I personally believe that we can’t know exactly how other people feel until we are in their shoes. I found this video that can almost simulate to be hearing impaired.

How did you feel? Wouldn’t that be difficult to live? The elderly usually have a combination of problems of this nature. How kind and patient we ought to be when taking care of them.

What a cochlear implant actually does…

A cochlear implant is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf or severely hard of hearing. As of April 2009, approximately 188,000 people worldwide had received cochlear implants. The implant is surgically placed under the skin behind the ear. The basic parts of the device are a microphone, a speech processor, a transmitter, and a receiver and stimulator. The stimulator in bone beneath the skin converts the signals into electric impulses, which our brain can understand.

The above picture shows the internal part of  a cochlear plant. In order to implant it, a surgeon actually destroys and removes the cochlea and uses that space for the devivce! That means, even if new technologies develop to restore the function of hair cells, it’s too late for those who have implanted.There is no way back! If your child was deaf, would you go ahead and implant by destroying his or her cochlea? Or would you wait and long for the possibility of a new technology to fix the problem?

Dancing Hair Cells!?

I found this video on youtube. It is literally a hair cell, responding to sound.

If we have the technology to pick up one hair cell, which we obviously see from the video, it may not be impossible to surgically implant healthy hair cells to people with hearing impairments…that would be amazing!

Meniere’s disease

Meniere’s disease is caused by an excess pressure in the cochlear fluid of the inner ear. Its symptoms are sensorineural hearing loss, tinnitus, nausea, and episodes of vertigo. Timely medical attention is necessary in its treatment.

Loss of or damage to the hair cells in the cochlea is the most serious of the various types of hearing impairmens. Some hair cells may be missing, some may increase spontaneous firings, some may require unusually strong stimuli to excite them, and some may suffer a loss in sharpness of tuning.  At present there is no known way to repair damaged hair cells or replace lost ones. The most effective solution to date is compensate with the use of hearing aids.

Tinnitus

Have you ever heard ringing, rushing, or roaring noises in the ear that come and go spontaneously without any sound stimulus? If it’s constant and persisting, it may be tinnitus, or “ringing in the ears.”

It is thought that the outer hair cells may be responsible for many cases of tinnitus, but the causes are hard to determine. Because of that, only about 10 % of the cases of tinnitus can be treated medically. That’s an awful low number!

Prevention becomes very important in any cases like this. 

According to the American Tinnitus Association, there are several things you can do to protect yourself from excessive noise related tinnitus:

• Protect your hearing at work. Your work place should follow Occupational Safety & Health Administration (OSHA) regulations. Wear ear plugs or earmuffs and follow hearing conservation guidelines set by your employer.
• When around any noise that bothers your ears (a concert, sporting event, hunting) wear hearing protection or reduce noise levels.
• Even everyday noises, such as blow drying your hair or using a lawnmower, can require protection. Keep ear plugs or earmuffs handy for these activities

This cannot be caused simply by aging. It is preventable!

Otitis media

Otiis media is the most common cause of conductive hearing loss. It is the inflammation of the middle ear. Here is the anatomy of it;

Infections are generally transmitted through the eustachian tube into the middle ear. It is known that children are more susceptible to such infections because of their shorter eustachian tubes.

The epidemiology of otitis media is shown above. The darker (more red) color indicates more incidents (the dark area means no data). Studies show that out of 10 million annual antibiotic prescriptions for ear infections, somewhere between 8.5 million and 9.5 million prescriptions didn’t help. It is because most ear infection is viral, not bacterial. I thought this was an very interesting research finding.

Homecare experience with my grandmother

Arranging homecare for aging parents can be a difficult process for many different reasons. My grandmother was homecared for about 10 years until she passed away last year, and it wasn’t the easiest thing to deal with sometimes because of her personal preferences (here, I mean, she was hearing impaired to some extent, but she did not want to put any hearing aids because she thought it would look bad), sudden sickness and injuries, and losing of her memory (to the point that she could not remember my name).

I came across an interesting article by Steven Schwartzman, Homecare Do’s and Don’ts. As I look at the list, I feel that we actually did well on taking care of my grandmother. It could have been much worse. It is a blessing to have a family. Without it, there would be no homecare.

How our ears work

I love it when I see different subjects come together to explain certain things. For example, in order to explain how our lungs work (biology or physiology concept), we must first understand Ideal Gas law (PV=nRT) from chemistry or physics. I won’t go into details here, but my p0int is that we must understand physics in order to understand how our ears work.

The sound is carried through movements (vibrations) of air molecules. In the air, the sound is in the form of acoustical energy. When the sound  comes in contact with the tympanic membrane (better known as the ear drum) or the middle ear, it gets converted to mechanical energy. The mechanical energy then goes through the inner ear through cochlea, and it is converted to electronic energy by the hair cells and is transmitted to the brain to “hear” the sound.

Knowing this will help us understand what needs to be done to fix problems associated with hearing. It makes sense why hearing aids don’t work for complete deaf people (who lost their hair cells). Hearing aids amplify the mechanical energy so that less sensitive parts of our ear can sense the energy, but it cannot play a role of hair cells to convert the mechanical energy to electronic energy. If the hair cells are lost (ex. due to genetics), cochlear implant is the only way to fix the problem (unless we could implant hair cells). The patient actually gets a device inside the ear that can send electric signals to the brain.

Isn’t it so cool to see how science helps us understand what actions we need to take to solve the problem? It became a little long, but I wrote this as basic knowledge for understanding hearing impairment.