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HOW WE HEAR

In essence, sound funnels into the ear canal and causes the eardrum to vibrate.  These vibrations are transmitted from the eardrum through the middle ear by three small bones to the cochlea, the main organ of hearing.  The vibrations cause movement in the fluid which fills the cochlea.  This movement in turn causes hair cells found in the cochlea to vibrate, creating nerve signals which are sent to the brain where they are interpreted.  The hair cells at one end of the cochlea respond to slower frequencies, corresponding to lower pitched sounds, while the hair cells at the other end of the cochlea respond to faster frequencies or higher pitched sounds.
  

How Are Hearing Sounds And Understanding Conversations Different

The ability to hear comes from your ears, but your ability to understand speech comes from your brain.  There are basically three sections in this process; the ear, the nerves that take the signal from the ear to the brain and the brain itself.

You may be familiar with the old adage: "Use it or lose it!"  The reality is that once you start losing your hearing, you also start losing your ability to understand what you are hearing.  You don't actually "hear" a sound until the brain's hearing centers receive the electrical signals from the inner ear and properly processes those signals.  Consequently, if those signals are missing or are diminished in quality, not only do the hearing nerves weaken over time, the hearing centers in the brain, if not used, also tend to weaken and atrophy.   So, if you are experiencing hearing loss, DO NOT DELAY in having your hearing tested and addressing any problems that you may be experiencing.

Now we have to get the signal to the brain.  Sometimes people have auditory processing difficulties that make speech difficult to understand when background noise or visual distractions are present.  The problem lies in the processing path the sound takes to the brain.  Think back to your school days.  Some people could study with a party going on while others need it quiet to soak the lesson in.

Why Is Hearing Loss So Difficult To Understand And Treat?

As previously mentioned, the human body operates on the "use it or lose it" principle, and hearing is no different.  Hearing loss is often gradual and, therefore, something to which one adapts.  There is a growing collection of detailed studies that show the sooner one treats hearing loss, the better the outcome one will have.  This is because the longer the problem is ignored, the harder it is to treat.

Hearing aids can do a great job in filling in the gaps that your inner ear is missing but they need help from the rest of your auditory system to get the light bulb in your brain to flash on.  Considerations that may help you:

Get the right hearing aids for your hearing loss.  Although most of the hearing aids available now are good at adjusting for your hearing loss, some are better than others at cutting out background noise or enhancing speech.
It takes time.  Over time the brain loses some of the synapses (connections) it needs to interpret the speech signal it is getting.  If you learned a foreign language a few years ago but didn't keep up with it, you'll have to relearn the vocabulary to understand it again.  Well, you brain has to relearn the "new sounds" it is hearing with hearing aids.  This can take weeks or even months.  The more you wear your hearing aids, the better your brain will get at interpreting the signal.
Proper expectations.  Even the best hearing aids can't repair dead inner ear hair cells or completely get rid of background noise.  You may never be able to hear as well as you once did, but the benefits hearing aids will bring can improve the quality of your life.
  

Anatomy of the Ear

As mentioned above, the auditory system is divided into three distinct parts. Each of these has an important role to play in the process off hearing.

Anatomy of the Ear

The Outer Ear - This is composed of:

  • The Pinna: This is the most visible part of the auditory system. It catches the sound waves and aims them into the internal mechanisms of hearing. If the pinna is missing or damaged, sound waves may not be collected properly.
  • The Auditory Canal: This structure simply conducts the sound waves to the internal structures.  Obstructions in the auditory canal, such as significant wax buildup or foreign bodies in the canal can significantly reduce the ability to hear.
  • The Tympanic Membrane:  Also called the ear drum, this structure vibrates in response to the sound waves striking it and transfers these vibrations to the middle ear.  Hearing may be affected if the ear drum is ruptured or diseased.

The Middle Ear - This is made up of:

  • The Ossicles:  These three bones are the smallest bones in the human body. They are most commonly referred to as the Hammer, the Anvil, and the Stirrup. Their job is to take the vibrations provided by the ear drum and transfer them to the organ of hearing, the cochlea.  Damage to these bones can affect the transmission process and, thus, result in diminished hearing.
  • The Eustachian Tube:  This is a small hollow pathway that runs from the middle ear to the back of the throat.  It's primary function is to help maintain a balance of air pressure on both sides of the ear drum.  Although not directly involved in the hearing process, hearing can be affected if this tube is blocked or becomes infected since the ability to maintain balanced air pressure may be compromised.  If you have ever descended quickly in an elevator or flown in an airplane, you may have noticed that your hearing is diminished significantly until you swallow and clear your Eustachian tube and restore equal air pressure to the middle ear.

The Inner Ear -  Consisting of:

  • The Cochlea:  This is the main organ of hearing.  it contains tiny receptors which take the vibrations sent to it from the ossicles and converts them into electrical signals which are then sent via the auditory nerve to the brain where they are interpreted as sound.  Damage to, or disease of the cochlea can have the greatest impact on the ability to hear.
  • The Semi-Circular Canals:  Although these play no part in the hearing process, these canals play a very important role in maintaining balance and bodily orientation. Persistent vertigo or dizziness may result from damage or disease to these canals.