How Hearing Works
Our sense of hearing, which allows us to receive and interpret sounds, is an amazing system. It is a complex process, not yet fully understood my modern science.
The ear (known as the outer pinna) directs sound waves down the auditory canal to the eardrum (known as the tympanic membrane), causing it to vibrate very slightly. The ossicles in the middle ear are the three smallest bones in the human body, and consist of the hammer (malleus), anvil (incus) and stirrup (stapes). They work as a lever system to amplify the vibrations, which are then passed along to a smaller vibrating membrane (known as the elliptical window) on the surface of the cochlea of the inner ear.
The mechanical energy of the sound, now translated to a physical vibration, creates compression waves within the fluid-filled spiral tube of the cochlea, which in turn move the tiny hair cells lining the inside of the cochlea. As the hairs move, nerve cells at their base change this motion into electrical signals that are passed along the auditory nerve to the central auditory processing centres of the brain, where the signals are interpreted as recognizable sound.
Hearing is not just a passive process; we have the ability to focus what we hear – imagine being in a crowded room and trying to hear a conversation going on a few meters away. Deciding which sounds to focus on is a central auditory process called gating, and is an active learned process.
Hearing Loss Causes
Hearing loss has many causes including noise overexposure, presbycusis (aging), congenital conditions, prenatal conditions such as fetal alcohol syndrome or conflicting parental blood types, heredity, disease, repeated ear infections, wax buildup, trauma to the head or ears, acoustic neuromas (tumors), auto-immune conditions, ototoxicity, and abnormalities of the tiny bones of the ears.
Overexposure to noise is the most common cause of hearing loss and is one that is within our ability to control.
Hearing Loss Treatment
Hearing Aids
Whether hearing loss is mild or severe, congenital or acquired in later life, there are many strategies that will help to dramatically improve communication and the overall quality of life for those affected. Modern technology has made life easier, safer and more accessible for those with hearing loss. Hearing aids, other assistive devices, captioning, computers, personal communication devices, and enhanced telephone capabilities combine to keep the great majority of people with hearing loss connected to other people, their work, and the world around them.
Hearing aids are often the first step to an effective communication strategy, yet only one in five of the more than three million Canadians who could benefit from a hearing aid actually obtains one.
The age-old stigma of hearing loss (“people will think that I’m old, not capable, not ‘with it’!”) that caused people to resist seeking hearing help and wearing hearing aids, is starting to dissipate. As a whole generation – baby boomers – becomes more and more affected by hearing loss due to age and noise-related issues, information and strategies to improve communication are increasing.
Hearing aid technology has exploded; people with hearing loss benefit from hearing aids, now available in a wide range of styles, technology, sizes and capabilities. The Canadian Academy of Audiology has an excellent section on hearing aids.
For more of this information please visit the Hearing Foundation of Canada Website: www.hearingfoundation.ca