The relative difference in the size of the tympanic membrane to the stapes footplate.
Because of this size difference, sound is concentrated as it reaches the inner ear, and the sound pressure is enhanced by about 27 DB.
What is Areal Ratio in the Ear?
The areal ratio is the ratio of the surface area of the tympanic membrane to the surface area of the stapes footplate. The tympanic membrane is the thin, cone-shaped membrane that separates the outer ear from the middle ear. The stapes footplate is the base of the stapes, which is the third and smallest of the three auditory ossicles in the middle ear.
The areal ratio of the human ear is approximately 20:1. This means that the tympanic membrane is about 20 times larger than the stapes footplate. This size difference allows the middle ear to amplify sound waves by about 27 decibels (dB).
What is the Area Ratio Advantage of the Middle Ear?
The areal ratio is one of the two main mechanisms by which the middle ear amplifies sound waves. The other mechanism is the lever action of the auditory ossicles. The lever action of the ossicles amplifies sound waves by about 1.3 times.
The combined effect of the areal ratio and the lever action of the ossicles is to amplify sound waves by about 28 dB. This amplification is necessary because the impedance of air is much lower than the impedance of the fluid in the inner ear. This impedance mismatch would prevent sound waves from being transmitted effectively to the inner ear without amplification.
What are The 3 Main Types of Hearing Loss?
There are three main types of hearing loss: conductive, sensorineural, and mixed.
- Conductive hearing loss occurs when there is a problem with the outer or middle ear. This can be caused by a buildup of earwax, a perforated eardrum, or a problem with the ossicles.
- Sensorineural hearing loss occurs when there is a problem with the inner ear or the auditory nerve. This can be caused by age, noise exposure, or certain medical conditions.
- Mixed hearing loss is a combination of conductive and sensorineural hearing loss.
What is the Normal Hearing Range in Hz?
The normal hearing range in humans is 20 Hz to 20,000 Hz. This means that humans can hear sounds that have frequencies between 20 and 20,000 cycles per second.
The ability to hear sounds at both low and high frequencies is important for understanding speech and other sounds. Low-frequency sounds are important for hearing the bass notes in music, while high-frequency sounds are important for hearing the high-pitched voices of children and women.
As people age, they often lose the ability to hear high-frequency sounds. This is because the hair cells in the inner ear become damaged over time. Damage to the hair cells can also be caused by noise exposure, certain medical conditions, and certain medications.
If you are experiencing hearing loss, it is important to see a doctor or audiologist for diagnosis and treatment. There are a number of treatment options available for hearing loss, including hearing aids, cochlear implants, and surgery.