How do we recognise sound?
Sound is a form of energy, just like electricity and light. A sound is made when air molecules vibrate and move in a pattern called waves, or sound waves. Think of when you clap your hands, or when you slam the car door shut. That action produces sound waves, which travel to your ears and then to your brain, which says, “I recognise that sound.”
How does sound travel?
Wavelengths for high frequency sounds are short whereas they are long for low frequency sounds. In general, low frequency sounds travel through hard surfaces (such as a wall) easier than high frequency sounds because of their longer wavelengths whereby they lose less energy in the process. This is why low frequency sounds like traffic are still often heard indoors despite windows and doors being closed.
How does hearing work?
Your ear has three parts that each play a role in bringing the sounds from the world around you to your brain where they are interpreted and given meaning.
The main role of your ear is to convert sounds that we hear into electrical impulses that are sent to the brain for interpretation. Sound is a fascinating concept to understand because it involves particles in the air bouncing off one another in a wave like fashion until they finally enter your ear. You have three different sections of your ear. The outer ear, middle ear and inner ear. Sound enters the outer ear where it is funnelled along your earcanal until it hits your tympanic membrane, also known as your ear drum.
- Outer ear: Includes the fleshy part that you can see called the pinna as well as the ear canal. This section collects and funnels soundwaves into your middle ear. What you actually hear are sound waves, which cause vibrations in the eardrum.
- Middle ear: Includes the tympanic membrane (ear drum), a chain of tiny bones behind it called ossicles and your eustachian tube (which connects your ear to the back of your throat and can cause pressure and equalisation problems). Your ossicles are three of the tiniest bones in the whole body and all three can fit on a 5c coin! This section increases the intensity of the soundwaves to help them reach your inner ear where they are converted into electrical signals to be sent to your brain for interpretation.
- Inner ear: Contains your organ of hearing, called the cochlea. It is a spiral-shaped structure that is filled with fluid and lined with 30 000 nerve innervations and around 15 000 tiny hairs cells (per cochlea), called stereocilia. This is quite remarkable, considering your cochlea is the size of a pea! Soundwaves enter the fluid-filled cavity, pushing against these tiny hair cells. This stimulation causes electrical signals, which are transmitted to the brain and become the sounds you recognise.
With healthy hearing, all these processes are synchronised and seamless. When any one of these tiny moving parts falls out of sync, it can lead to hearing loss.
If you would like to learn more about the mechanisms behind hearing, why not download our e-book and give it a read? (click here for access)
Alterantively, if you have concerns about your hearing or would like to know how all three parts of your ear are functioning, book in to see our Audiologist today. Give us a call on (07) 3310 4494.
