Our ears, when working properly, are sophisticated organs capable of processing sounds from the scarcely audible to extremely loud. Our ears can assess volume and how close or far away sounds are and identify where sounds originate with a great deal of accuracy. The following explains how this deceptively simple process works.
The ear, in three parts
The human ear is constructed with three sections.
- The outer ear
- The middle ear
- The inner ear
The outer ear is the visible part, also called the pinna or auricle. It consists of skin and cartilage with muscles attached to the back. The pinna’s primary function is to collect and direct sounds down the ear canal. Constructed of twists and folds that enhance high frequency sounds and help determine the direction of the sound source, sounds coming from the front and to your side are slightly enhanced as they are directed into the ear canal, while sounds from behind you are somewhat less pronounced. This helps you hear whatever you are looking at while reducing distracting background noise. If your pinna is functioning normally, it is providing about 5 dB (decibels) of high frequency enhancement, as well.
The ear canal is also part of the outer ear. This letter S shaped passage is approximately one inch in length, and roughly the diameter of a pencil eraser. The outer portion of the ear canal is surrounded by cartilage and contains glands that produce cerumen (more commonly known as earwax) while the inner portion is encased by bone.
A word about earwax—although you may think of it as an annoyance to be removed, it actually provides the following three vital functions:
- Protects your skin and tympanic membrane from drying out
- Helps guard against intrusion by foreign bodies (e.g., dust, insects)
- Helps keep unhealthy bacteria from multiplying
The resonant tubes of the ear canal also increase gain (amplification) by 15–25 dB as sound is conducted toward the middle ear.
Your middle ear is separated from the outer ear by the tympanic membrane (eardrum). Directly behind the eardrum is a row of three tiny bones collectively known as the ossicles. These consist of the following:
- Malleus (the hammer)
- Incus (the anvil)
- Stapes (the stirrup)
The ossicles vibrate in response to eardrum stimulation, amplifying and relaying sound to the inner ear through an oval window. They also boost the sound gain by an additional 27 dB.
The opening to the Eustachian tube also ventilates your middle ear, connecting it to the back of your throat. This tube opens when you swallow, yawn, blow your nose, or cough.
Your inner ear, which is shaped a lot like a snail’s shell, is divided into two functionally separate sections, the vestibular, or balance organ and the cochlea, or hearing organ. The cochlea conducts high frequencies at its base and low frequencies at its apex. You lose hearing at the higher frequencies earlier because the sound wave always passes through the base first.
The sound wave causes the fluid in the inner ear to move, stimulating rows of thousands of tiny hair cells (hearing nerve cells) inside the cochlea for each particular frequency. These hairs, which assist in how you perceive the loudness of a sound among other functions, release neurotransmitters via the auditory nerve to the brain, which will interpret them as sounds. These hair cells are delicate and can be damaged or destroyed due to overexposure to loud noise, genetic predisposition, or the aging process. Once you lose a hair cell, it cannot be replaced with today’s technology. The more of these you lose, the less hearing you retain.
Wonder why we hear better with two ears? Pretty much for the same reason that stereos sound better than single-speaker audio. Binaural hearing, or hearing equally well through two ears, increases the depth and richness of sound, along with providing other listening benefits.
Contact a hearing care professional now
Our ears are wonders of natural development and provide a vital sensory experience. If you suspect yours are no longer functioning the way they should, call 855-355-9064 or contact us online to schedule a no-obligation appointment. Get tested today!