Subtypes of Hearing Loss

PRESBYCUSIS

Presbycusis is the global term to refer to hearing loss associated with the aging process. Hearing loss is a known companion to the Elderly. Seniors born before 1945 are referred to as the Traditional Seniors whereas the younger Seniors born from 1945-1965 are called the Baby Boomers. Hearing loss is indeed the third largest chronic disability in Seniors, with vision and arthritis ranking in first and second place.

Presbycusis is typically a sensorineural hearing loss that tends to affect the higher frequencies or pitches first. High-frequency hearing loss has long posed special challenges for those with hearing loss. People with high-frequency hearing loss have trouble hearing higher pitches, such as women’s and children’s voices, and certain parts of speech, such as consonants. It is especially difficult to converse in groups and understand in background noise. They can hear but not understand what is being said, and especially so in background noise such as in family gatherings, restaurants. And because it is so slow in its development, it is very difficult for a Senior to recognize the loss of hearing. In fact, it is very common to have a family member or a close friend comment on one’s hearing.

Some Seniors lose their hearing earlier than others. Recent research indicates that several genes may be responsible for hearing loss and a common variant in the GRM7 gene may be involved.

Untreated hearing loss leads to auditory deprivation. The ability to understand speech can deteriorate if the loss remains untreated. Psychological effects such as depression, anxiety, frustration, paranoia can develop as well. Further, there is growing evidence suggesting that untreated hearing loss can lead to memory loss and cognitive decline. Studies are currently being conducted on hearing loss and dementia.

In recent years, there have been great strides in developing hearing aids that are effective for all types of hearing loss — including high-frequency hearing loss.

AUDITORY DEPRIVATION – “USE IT, OR LOSE IT”

Auditory deprivation refers to a person’s lack of adequate hearing stimulation. The human body operates like the old expression “if you don’t use it, you’ll lose it”. The auditory system, your ability to hear and understand speech, is no different!

LACK OF AUDITORY STIMULATION

With auditory deprivation, the brain gradually loses some of its information processing ability. In other words, the ability to process speech declines due to a lack of stimulation. This will affect your general hearing ability.

REHABILITATION

The body’s various systems – bones, muscular, sensory and other systems can weaken with prolonged non-use. When you get an injury such as breaking your hand, the physical therapist gives you rehabilitation exercises. It has been proven that the sooner you get to work on rehabilitating your hand, the faster your recovery period. Getting sound amplification, such as a hearing aid, will rehabilitate and help improve your quality of life.

AVOIDING AUDITORY DEPRIVATION – DON’T WAIT

The key to avoiding auditory deprivation is to keep the auditory system active. Unfortunately, many individuals with hearing loss wait many years before trying hearing aids. However, the sooner you start wearing hearing aids, the faster you will be able to properly stimulate the auditory system and the brain.

EARLY DETECTION

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Don’t deprive your hearing and quality of life!

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NOISE INDUCED HEARING LOSS

Noise, simply stated, is unwanted sound. Continued exposure to noise (e.g. working with loud equipment) or a one-time exposure to an intense impulse noise (e.g. gunshot) can cause hearing loss. Loud sounds overstimulate the sensitive structures of the inner ear leading to injury or loss of hair cells. The resulting sensorineural hearing loss can be temporary or permanent. Noise exposure can also cause tinnitus or ringing in the ears. The tinnitus may disappear after some time or remain constant. Hearing loss and/or tinnitus may affect one or both ears. Noise-induced hearing loss is the #1 occupational disability:

  • It is painless
  • It is progressive over time
  • It is typically permanent and irreversible
  • It is preventable

WHAT SHOULD BE DONE TO PREVENT IT?

  • Annual hearing tests: Find out before it’s too late
  • Hearing conservation (protecting devices such as noise plugs, earmuffs, musician’s ear plugs)

WHERE CAN I GET HEARING PROTECTION?

Pre-formed plugs may be available in Pharmacies and safety stores or from the employers.

Custom made ear plugs are available at our clinics. These types include Noise earplugs, Musicians’ earplugs, Pilot earmolds, Hunters’ earplugs.

WHEN DO I NEED TO WEAR PROTECTION?

  • Steady state noise measured at 85dBA or greater. Ex. a pneumatic drill, an airplane
  • Impulse noise measured at 140dBA or greater. Ex. a 12 gauge Shotgun and Hunters beware
  • Any loud sound that causes ringing (tinnitus) in the ears. Ex. a loud concert

There are other sources as well. Those in the performing arts for example, and those who listen to music, who play in a band or orchestra can sustain a noise-induced hearing loss. According to Audiologist and Director of Auditory Research at the Musicians’ Clinics, Marshall Chasin, AuD: “There are many sources of noise in the music industry — explosions, loud cymbal crashes, feedback from speakers… It’s not just rock music- it can be your Walkman, or even a symphony!”

ARE THERE OTHER WAYS THAT I CAN PREVENT HEARING LOSS?

According to audiologist Marshall Chasin, Doctor of Audiology, suggests one “strategy is to hum while you work. Humans (and all other mammals) have a small muscle in their middle ears that contract upon loud sounds. From an evolutionary perspective, we have such a muscle so that our own voice would not be too loud for us. When this muscle (called the stapedius muscle) contracts, it pulls on the chain of bones in the ear that conduct sounds, making them less efficient as conductors. Sound from the environment therefore cannot get through to our ears as readily, thus providing us with significant protection. If you know that a loud sound or blast is about to occur, start humming before the blast and continue until the blast is finished. Drummers have known this for years without being told.”

CAN QUIET NOISES CAUSE HEARING LOSS?

According to the director of the Musician Clinics of Canada, “quiet noises, if one listens to them long enough, can damage one’s hearing. A dial tone on a telephone, if listened to long enough, can cause a permanent hearing loss. A permanent hearing loss can be the result of a single loud blast, but more often it is the result of years of exposure to sounds that one would not normally think of as “damaging.”

AUDITORY NEUROPATHY

What is it?

Another type of sensorineural hearing loss, Auditory Neuropathy Spectrum Disorder (ANSD) is a confusing diagnosis and condition to many. It affects the neural processing of auditory stimuli. Persons with ANSD respond to sounds appropriately, but their ability to understand speech is impaired. In other words, ANSD “…is a hearing disorder in which sound enters the inner ear normally but the transmission of signals from the inner ear to the brain is impaired.”

Historical Background

In the late 1970s: Researchers and Clinicians began describing patients who had normal hearing (and even some with mild hearing loss) but for some reason had absent or severely abnormal auditory brainstem responses (ABRs).

In the mid 1980s: Although otoacoustic emissions (OAEs) were known and described in the 70s, it was not until the mid 80s that otoacoustic emissions (OAEs) were routinely being used clinically. It was found that these patients had normal OAEs, in other words, normal cochlear function.

In the mid 1990s: Auditory neuropathy (AN) was defined when normal cochlear (inner ear) function but with abnormal brainstem responses were measured. However, further investigations led some researchers to the conclusion that AN may truly represent a dyssynchronous auditory nerve rather than a neuropathy. A new terminology evolved and the condition was referred to as auditory dyssynchrony (AD). (Auditory Neuropathy: Wayne T Shaia, MD; Chief Editor: Arlen D Meyers, MD, MBA Updated Apr 13, 2012)

Theories on site of the damage: Damaged specialized inner ear hair cells; Defective connections between the inner hair cells and the nerve leading from the inner ear to the brain; Damage to the nerve itself; A combination of all of the above.

Several Factors Leading To Possible Causes In Children:

  • Health problems as newborns, or during or shortly before birth, such as jaundice, premature birth, low birth weight, inadequate supply of oxygen to the unborn baby
  • Some drugs used to treat medical complications in pregnant women or newborns may damage the inner hair cells
  • Genetic factors
  • Some with other neurological disorders such as Charcot-Marie-Tooth syndrome and Friedreich’s ataxia also have ANSD

How is ANSD diagnosed?

A combination of methods is used to diagnose auditory neuropathy by a team of Health Professionals, including: Audiologists, Pediatricians, Otolaryngologists.

Our Audiologists perform a battery of tests:

Speech testing as part of their routine audiological assessments (Hearing Test). ANSD can be suspected if speech perception or difficulty recognizing spoken words is worse than would be predicted by the degree of hearing loss.

Additional testing would include auditory brainstem response (ABR) and otoacoustic emissions (OAE). No ABR responses or severely abnormal ABR responses together with normal OAE results is indication that the person has ANSD.

How can ANSD be treated?

There is still no known cure for ANSD. The following are some recommendations by Audiologists:

  • Parents should work with a team of professionals to discuss options
  • Early identification of Hearing Loss in the Newborn
  • Parents should know what to look for (Parent’s Guide to Hearing ENGLISH Version, FRENCH Version)
  • Parents should continue to interact and communicate with their child (holding, facing, smiling at, talking to and responding to)
  • Hearing aids, cochlear implants, and other personal devices such as FM (frequency modulation) systems
  • Teach communication skills for children (Sign language and/or spoken English and/or Speechreading)
  • Speechreading for adults and older children who have already developed spoken language

Research on ANSD continues to try to find the causes of this disorder as well as to provide the most effective treatments.