What is Hearing Loss?
Hearing loss is any reduction in the body’s ability to capture or decipher sound. It can involve dysfunction in the measurable volume of sound heard, and/or the loudness of sound interpreted, which is a function of frequency. In other words, hearing loss involves both the quantity and quality of sound. The term decibel (dB) is the unit of measurement used to accurately measure the volume of sound. To get a perspective, normal speech is about 60 dB. Any decrease of more than 10 dB in an individual’s ability to hear is considered significant hearing loss.
Hearing loss is a very common problem in our society. About 28 million people in the United States are hearing impaired, with men at a slightly greater risk then women. It is estimated that approximately 33% of Americans over the age of 60 suffer from some degree of hearing loss, and the percentage jumps to about 50% for those over 85. However, hearing loss is not restricted to the aged. It can and does affect people of all ages, including many children. Exposure to loud noise levels and heredity are thought to be the main causes of hearing loss in most people. In the majority of cases, hearing loss is not reversible. However, there are treatment options that are able to significantly help many folks improve their hearing, as well as practical steps that can be taken to prevent hearing loss.
What Are the Signs and Symptoms of Hearing Loss?
There are a handful of common signs of hearing loss that you may want to be aware of in your own life and the lives of loved ones. These include:
- Muffled perception of speech and other sounds. This usually indicates an overall hearing problem that is associated with reduced volume of sound.
- Difficulty hearing or understanding spoken language. This may point to hearing loss related to certain frequencies. In most languages, speech is communicated using the higher frequencies.
- Difficulty separating speech from background noise, especially in a crowd.
- A need for higher volume on the television or radio.
- Asking others to speak up, or to speak more slowly or clearly.
- Habitually withdrawing from conversations.
- Avoiding social situations.
What Are the Causes of Hearing Loss?
Before we discuss specific causes of hearing loss, I think it would be helpful to have a basic understanding of the structure of the ear and of how the hearing process works.
In a nutshell, we hear when sound waves pass from the source through the various structures of the ear, and are eventually converted into electrical impulses that the brain is able to interpret as sounds. The structure of the ear is broken down into three major categories: outer ear, middle ear, and inner ear.
- Outer ear: Sound travels through the air (or water) in waves. These sound waves are collected or “funneled” by the outer ear, and the energy of the waves causes a structure separating the outer and middle ear called the tympanic membrane (or eardrum) to vibrate.
- Middle ear: The eardrum is connected to three tiny bones within the middle ear: the malleus (hammer), incus (anvil), and stapes (stirrup). These bones are collectively known as the “the chain of ossicles.” As they transport the vibrations, they function to amplify the sound by about twenty times.
- Inner ear: The wave continues to the oval window, which is an opening covered by another membrane that leads to the liquid-filled inner ear. There the energy creates a “standing wave” within the endolymph, also known as Scarpa’s fluid, which is the potassium-rich watery liquid of the inner ear. A standing wave is one that is stationary, much like you would see in a vibrating glass of water. The configuration of this wave is dependent on the frequency of the sound generating it. The wave vibrates within a snail-shaped structure of the inner ear called the cochlea. The wave is centered in the “Organ of Corti,” which is composed of 15,000-20,000 auditory nerve receptors, each with its own hair cell. These tiny hairs are involved with translating the sound into electrical signals that the brain can interpret as sound. Different sounds affect these hairs in different ways, and that is how the brain is enabled to distinguish between many types of sounds.
- The journey can be summarized as follows:
ü Sound travels via air from the outer ear to the eardrum.
ü Then it is conducted via bone within the middle ear.
ü Within the inner ear, the sound travels through fluid to the Organ of Corti.
ü In the inner ear, it is transformed into electrical signals and travels via nerves to the brain.
ü The brain can then interpret and sort the various sounds.
The causes of hearing impairment are related to interruptions that occur anywhere along the path of this journey. Hearing loss can be classified into three major types: conductive, sensory, or neural.
- Conductive hearing loss occurs in the outer or middle ear.
ü In the outer ear, the most common cause for hearing loss is the blockage of the ear canal by any foreign object. Wax is the most likely culprit, and hearing impairment due to wax in the ear is one of the most oft-found causes in all age groups. Infections and tumors can also make it difficult or impossible for sound waves to reach the eardrum. A special condition that often affects surfers can cause the bone of the ear canal to grow abnormally large, thereby narrowing the passageway. The cause of this is thought to be repeated flushing of the ear canal with cold water. Known as “Surfer’s Ear,” this malady is often reported by surfers who populate the cold ocean waters off the coast of Northern California.
ü Sometimes the eardrum can be the source of trouble. This membrane is very thin and translucent, and you can actually see through it. The eardrum can be easily punctured, thereby interrupting the journey of the sound waves. Ruptures can occur due to extremely loud noises (such as an explosion), sharp objects (be careful when cleaning the ears with q-tips), trauma (from an accident or firm slapping of the ear), or even as the result of pressure from middle ear infections. Scuba divers have to be careful as well, as increased atmospheric pressure has been known to rupture the eardrum.
ü In the middle ear, certain conditions can impede the operation of the ossicles. Infections referred to as otitis media can cause fluid composed of mucus or pus to accumulate and interfere with the movement of the ossicles. A disease called otosclerosis can also cause the stapes to bind up in the oval window and produce hearing impairment or even complete deafness.
- Sensory hearing loss takes place in the confines of the inner ear. Many of these factors damage the fine hairs in the Organ of Corti by bending them or breaking them off. Some common causes of sensory hearing loss include:
ü Exposure to loud noise over time is one of the most common causes of sensory hearing loss, and in fact is the leading cause of hearing impairment of any kind. This category is referred to as “Noise Induced Hearing Loss” (NIHL). Over a million individuals are diagnosed with NIHL, and it is one of the leading reasons that many young men are not deemed fit for duty in the military. This phenomenon is probably linked to prolonged exposure to excessively loud rock music. Other loud noises that can endanger your hearing include discharging firearms, and noise from operating vehicles such as snowmobiles, motorcycles, and lawn care equipment.
ü One particular source of NIHL is called “occupational hearing loss,” and is related to damaging levels of noise exposure on the job. Construction or factory workers are quite susceptible to high levels of noise, and anyone who is in an environment such as this should be careful to wear protective gear designed to preserve their hearing. Occupational hearing loss is not as big of an issue as it once was, as laws have been passed in the last several decades that mandate the protection of workers.
ü Presbycusis is a form of sensory hearing loss that is most common in folks over the age of 65. It is attributed to the progressive wear and tear on the hearing over the years, and is typically a function of aging.
ü NIHL and presbycusis are factors that are especially damaging to hearing high frequency noises, and therefore make it difficult for many folks to hear speech and conversations in a crowd of people. This kind of hearing loss can be especially troublesome in family, work, and social situations.
ü Certain illnesses such as meningitis (inflammation of the lining of the brain) and Meniere’s disease (a disorder of the inner ear) can also cause sensory hearing loss.
ü High doses of certain medications, such as aspirin and some antibiotics can also result in hearing impairment.
- Neural hearing loss is the final major category. This type occurs as the result of anything that damages the brain or acoustic nerve. Neural hearing loss is the most likely form to cause permanent, irreversible damage. Causes of this include acoustic neuromas (tumors of the nervous system), strokes, and multiple sclerosis (MS).
- Genetic causes of hearing loss are estimated to account for many cases of hearing dysfunction. Despite serious research on this matter, not much has been discovered regarding specific genes that may contribute to this.
- Tinnitus is a condition that impairs hearing in kind of a unique way: by creating extra noise that blocks out meaningful sounds. The patient may hear sounds such as clicking, blowing, or ringing that can only be heard by them. Tinnitus is caused by many of the same conditions that cause other forms of hearing loss.
What Treatments Are Available for Hearing Loss?
- Simply cleaning the wax out of your ears can clear up hearing problems in many cases. You can carefully do this yourself, of have it done by a health care practitioner.
- Hearing aids are effective for many folks. They typically work by gathering sound with a microphone, and then amplifying it before it is drawn into the ear. Hearing aids are able to increase the volume of most sounds by up to 70 dB.
- Cochlear implants are an option usually reserved for more severe hearing loss. They involve devices which do more than just amplify noise, like hearing aids. Cochlear implants actually compensate for damaged or nonworking structures within the ear.
- Before choosing any course of action, be sure you are informed and get a second opinion. Not all approaches work well for everybody, and certain types of hearing loss respond better to certain treatments.
- Preventing hearing loss is the best alternative of all. Take matters into your own hands and protect your hearing. Avoid excessive noise levels whenever possible, and it you must be exposed, wear protection. The best treatment begins before you experience hearing loss.